What does one mole count?

Exactly 6.02214076 × 10^23 representative particles.

What does a peak in an element's mass spectrum represent?

An isotope with a particular mass-to-charge ratio; for singly charged monatomic ions, the position tracks isotopic mass.

What does an empirical formula show?

The lowest whole-number ratio of the elements' atoms in a compound.

How does a mixture differ from a pure substance at the particle level?

A mixture contains chemically distinct representative units in variable proportions; a pure substance contains one element or compound with fixed composition. Different isotopes do not make an elemental sample a mixture.

Which particles make up an atom's nucleus?

Protons and neutrons. Electrons occupy the space outside the nucleus.

What does a larger binding energy on a PES spectrum mean?

More energy is required to remove that electron, so it is held more strongly by the nucleus.

How does atomic radius generally change across a period and down a group?

It decreases from left to right as effective nuclear charge rises, and it increases down a group as additional electron shells increase distance and shielding.

What typical ion charge do Group 1 metals form?

+1, by losing their one valence electron.

How do you convert moles to particles?

Multiply by Avogadro's number: particles = moles × 6.022 × 10^23 mol^-1.

How is average atomic mass estimated from isotope data?

Add each isotopic mass multiplied by its fractional abundance.

How is an element's mass percent in a compound calculated?

Divide the mass contributed by that element by the compound's molar mass, then multiply by 100%.

How can measured elemental composition reveal a sample's purity?

Compare the measured mass fraction with the fraction expected for the pure compound; a mismatch indicates another component.

How do you build a ground-state electron configuration with the Aufbau principle?

For ordinary ground states, move through the periodic table in atomic-number order, filling each s, p, d, or f block as it appears. The subshell capacities are s², p⁶, d¹⁰, and f¹⁴. For example, Br is [Ar] 4s² 3d¹⁰ 4p⁵.

What does the relative area or height of an ideal PES peak indicate?

The relative number of electrons in the corresponding subshell.

How does first ionization energy generally change across a period and down a group?

It increases from left to right as effective nuclear charge rises, and it decreases down a group as distance and shielding make a valence electron easier to remove.

Why do elements in the same group form similar compounds?

Their ground-state valence patterns repeat, including which outer subshells are full or partly full. That leads to similar bonding and typical ion charges.

How do you convert a sample's mass to moles?

Divide its mass by its molar mass: n = m/M.

Which mass-spectrum interpretation lies outside the usual single-element model used in this deck?

Assigning peaks in mixtures or peaks from multiply charged or polyatomic species; the standard model uses singly charged monatomic ions of one element.

What does the law of definite proportions state?

Every pure sample of a given compound has the same element mass ratios.

Why can two samples of the same mixture have different compositions?

Mixture components are physically combined, so their relative amounts are not fixed by a chemical formula.

How does Coulomb's law connect charge and separation to attraction?

Attraction grows with the magnitude of the charge product and decreases with the square of the separation distance.

Which PES electrons usually appear at the highest binding energy?

Core electrons closest to the nucleus, because they feel the strongest nuclear attraction.

How does electron affinity generally change across a period and down a group?

Electron gain generally becomes more favorable from left to right across a period and less favorable down a group as distance and shielding increase. Stable subshell patterns create substantial exceptions.

Why are alkali metals generally more reactive down the group?

Their valence electron is farther from the nucleus and easier to remove.

How many moles are in 18.0 g of H₂O?

About 0.999 mol. Use 18.0 g ÷ 18.02 g mol^-1.

An element is 75% isotope 10 and 25% isotope 11; what is its average atomic mass?

10.25 u. Calculate (0.75 × 10) + (0.25 × 11).

A compound is 40.0% C, 6.7% H, and 53.3% O by mass; what is its empirical formula?

CH₂O. For a 100 g sample, convert each mass to moles and divide by the smallest amount.

A 10.0 g impure sample contains 8.5 g of the target compound; what is its mass-percent purity?

85%. Calculate (8.5 g ÷ 10.0 g) × 100%.

Which electrons are removed first when a transition metal forms a cation?

Electrons in the occupied orbital with the highest principal quantum number: 4s before 3d. For example, Fe²⁺ is [Ar] 3d⁶.

A PES spectrum has peaks proportional to 2, 2, and 6 electrons; which configuration fits?

1s² 2s² 2p⁶, the configuration of Ne.

How does electronegativity generally change across a period and down a group?

It increases from left to right across a period and decreases down a group as atomic size and shielding increase.

What empirical formula results from Al³⁺ and O²⁻?

Al₂O₃, because two Al³⁺ ions balance three O²⁻ ions.

How does a particle's mass in atomic mass units relate to its molar mass?

The numerical value is the same: a molecular or formula-unit mass of x u corresponds to a molar mass of x g mol^-1.

What does the tallest isotope peak usually indicate in a simple mass spectrum?

The most abundant isotope, assuming comparable detection response and singly charged ions.

How much oxygen is present in 25.0 g of a compound that is 32.0% oxygen by mass?

8.00 g O. Multiply 25.0 g by 0.320.

What does a particle diagram with two unbonded species in changing ratios represent?

A mixture, because more than one particle type is present and the ratio is not fixed in a formula unit.

What distinguishes valence electrons from core electrons?

Valence electrons are available for bonding or ion formation; main-group valence electrons occupy the outermost shell, while transition metals may also use (n−1)d electrons. Core electrons mainly shield nuclear charge.

Why can PES peak groups reveal an atom's occupied subshells?

Electrons in different subshells require distinct removal energies, producing separate binding-energy groups.

How do ion radii compare with neutral atoms and within an isoelectronic series?

Cations are smaller than their neutral atoms, while anions are larger. Among species with the same electron count, more protons pull the electrons closer and produce the smaller radius.

What formula is expected for a compound between a Group 2 metal M and a Group 17 nonmetal X?

MX₂, because M forms M²⁺ and X forms X⁻.

When is a covalent bond considered nonpolar?

When the bonded atoms have identical or very similar electronegativities, so the shared electron density is distributed approximately evenly.

Why does a bonded pair of atoms have an equilibrium bond length?

At that separation, attractive and repulsive interactions balance at minimum potential energy.

How are particles arranged in an ionic solid?

Cations and anions occupy a repeating three-dimensional lattice held by electrostatic attraction.

What model explains bonding in a metal?

Positive metal cores are held together by attraction to mobile, delocalized valence electrons.

How do you construct a Lewis diagram?

Count total valence electrons, adding electrons for a negative charge and subtracting them for a positive charge. Choose a skeleton, connect atoms with single bonds, complete terminal duets or octets, and place remaining electrons on the central atom. Add multiple bonds if needed, then check the electron total and formal charges.

What does resonance mean in a molecule or ion?

Resonance uses two or more valid Lewis diagrams with the same atom arrangement but different electron placement. The actual electron distribution is a hybrid; equivalent contributors have equal weight.

What determines molecular shape in VSEPR theory?

Electron domains around the central atom arrange to minimize repulsions.

How does an ionic bond differ from a covalent bond?

Ionic bonding is attraction among oppositely charged ions in an extended structure; covalent bonding uses shared electron density between atoms.

What happens to potential energy when bonded atoms are pushed much closer than equilibrium?

Potential energy rises sharply because nucleus–nucleus and electron–electron repulsions dominate.

Why are many ionic solids brittle?

A shifted lattice can align like charges, creating strong repulsion that splits the crystal.

What molecular shapes arise from two electron domains with no lone pairs and from three domains with zero or one lone pair?

Two bonding domains give linear with a 180° angle. Three domains with no lone pairs give trigonal planar with 120° angles; replacing one bond with a lone pair gives bent with an angle slightly below 120°.

Advanced High School Chemistry Flashcards: Complete 9-Part Course Review

Review a rigorous nine-part high school chemistry course with 450 concise cards covering concepts, models, equations, calculation setup, and lab reasoning.

من إعداد Flashcards Open Source App

حول هذه الرزمة

Study advanced high school chemistry through 450 independently written English flashcards arranged as one nine-part sequence. The course moves from atomic structure and bonding to properties of substances and mixtures, reactions, kinetics, thermochemistry, equilibrium, acids and bases, thermodynamics, and electrochemistry. Prerequisites appear before dependent models and calculations.

What the cards practice

The cards practice five useful recall paths: concept to explanation; model or representation to interpretation; equation to meaning and use; short setup to a result with units and reasoning; and laboratory observation to a chemical conclusion. This includes definitions, relationships, conditions, contrasts, particle and energy models, focused calculation steps, measurements, errors, and visible changes.

Selected reverse and contrast prompts appear only when the reverse direction has one clear standalone target. Mechanical permutations, graph-dependent prompts that need a missing figure, copied test formats, long multipart derivations, and visual recall tied to third-party figures are excluded. The review scheduler handles long-term spacing after installation.

The prompts, answers, examples, organization, metadata, and cover were created independently from common chemistry knowledge and original work. No protected questions, answer choices, scoring materials, curriculum prose, commercial card text, source figures, or third-party media were copied.

The Common knowledge · CC0 1.0 label applies only to the original prompts, answers, examples, organization, metadata, and cover, to the extent applicable rights exist. It does not claim ownership of scientific facts, equations, or third-party material.

بطاقات هذه الرزمة

البطاقة ١
السؤال
What does one mole count?
الإجابة
Exactly 6.02214076 × 10^23 representative particles.
البطاقة ٢
السؤال
What does a peak in an element's mass spectrum represent?
الإجابة
An isotope with a particular mass-to-charge ratio; for singly charged monatomic ions, the position tracks isotopic mass.
البطاقة ٣
السؤال
What does an empirical formula show?
الإجابة
The lowest whole-number ratio of the elements' atoms in a compound.
البطاقة ٤
السؤال
How does a mixture differ from a pure substance at the particle level?
الإجابة
A mixture contains chemically distinct representative units in variable proportions; a pure substance contains one element or compound with fixed composition. Different isotopes do not make an elemental sample a mixture.
البطاقة ٥
السؤال
Which particles make up an atom's nucleus?
الإجابة
Protons and neutrons. Electrons occupy the space outside the nucleus.
البطاقة ٦
السؤال
What does a larger binding energy on a PES spectrum mean?
الإجابة
More energy is required to remove that electron, so it is held more strongly by the nucleus.
البطاقة ٧
السؤال
How does atomic radius generally change across a period and down a group?
الإجابة
It decreases from left to right as effective nuclear charge rises, and it increases down a group as additional electron shells increase distance and shielding.
البطاقة ٨
السؤال
What typical ion charge do Group 1 metals form?
الإجابة
+1, by losing their one valence electron.
البطاقة ٩
السؤال
How do you convert moles to particles?
الإجابة
Multiply by Avogadro's number: particles = moles × 6.022 × 10^23 mol^-1.
البطاقة ١٠
السؤال
How is average atomic mass estimated from isotope data?
الإجابة
Add each isotopic mass multiplied by its fractional abundance.
البطاقة ١١
السؤال
How is an element's mass percent in a compound calculated?
الإجابة
Divide the mass contributed by that element by the compound's molar mass, then multiply by 100%.
البطاقة ١٢
السؤال
How can measured elemental composition reveal a sample's purity?
الإجابة
Compare the measured mass fraction with the fraction expected for the pure compound; a mismatch indicates another component.
البطاقة ١٣
السؤال
How do you build a ground-state electron configuration with the Aufbau principle?
الإجابة
For ordinary ground states, move through the periodic table in atomic-number order, filling each s, p, d, or f block as it appears. The subshell capacities are s², p⁶, d¹⁰, and f¹⁴. For example, Br is [Ar] 4s² 3d¹⁰ 4p⁵.
البطاقة ١٤
السؤال
What does the relative area or height of an ideal PES peak indicate?
الإجابة
The relative number of electrons in the corresponding subshell.
البطاقة ١٥
السؤال
How does first ionization energy generally change across a period and down a group?
الإجابة
It increases from left to right as effective nuclear charge rises, and it decreases down a group as distance and shielding make a valence electron easier to remove.
البطاقة ١٦
السؤال
Why do elements in the same group form similar compounds?
الإجابة
Their ground-state valence patterns repeat, including which outer subshells are full or partly full. That leads to similar bonding and typical ion charges.
البطاقة ١٧
السؤال
How do you convert a sample's mass to moles?
الإجابة
Divide its mass by its molar mass: n = m/M.
البطاقة ١٨
السؤال
Which mass-spectrum interpretation lies outside the usual single-element model used in this deck?
الإجابة
Assigning peaks in mixtures or peaks from multiply charged or polyatomic species; the standard model uses singly charged monatomic ions of one element.
البطاقة ١٩
السؤال
What does the law of definite proportions state?
الإجابة
Every pure sample of a given compound has the same element mass ratios.
البطاقة ٢٠
السؤال
Why can two samples of the same mixture have different compositions?
الإجابة
Mixture components are physically combined, so their relative amounts are not fixed by a chemical formula.
البطاقة ٢١
السؤال
How does Coulomb's law connect charge and separation to attraction?
الإجابة
Attraction grows with the magnitude of the charge product and decreases with the square of the separation distance.
البطاقة ٢٢
السؤال
Which PES electrons usually appear at the highest binding energy?
الإجابة
Core electrons closest to the nucleus, because they feel the strongest nuclear attraction.
البطاقة ٢٣
السؤال
How does electron affinity generally change across a period and down a group?
الإجابة
Electron gain generally becomes more favorable from left to right across a period and less favorable down a group as distance and shielding increase. Stable subshell patterns create substantial exceptions.
البطاقة ٢٤
السؤال
Why are alkali metals generally more reactive down the group?
الإجابة
Their valence electron is farther from the nucleus and easier to remove.
البطاقة ٢٥
السؤال
How many moles are in 18.0 g of H₂O?
الإجابة
About 0.999 mol. Use 18.0 g ÷ 18.02 g mol^-1.
البطاقة ٢٦
السؤال
An element is 75% isotope 10 and 25% isotope 11; what is its average atomic mass?
الإجابة
10.25 u. Calculate (0.75 × 10) + (0.25 × 11).
البطاقة ٢٧
السؤال
A compound is 40.0% C, 6.7% H, and 53.3% O by mass; what is its empirical formula?
الإجابة
CH₂O. For a 100 g sample, convert each mass to moles and divide by the smallest amount.
البطاقة ٢٨
السؤال
A 10.0 g impure sample contains 8.5 g of the target compound; what is its mass-percent purity?
الإجابة
85%. Calculate (8.5 g ÷ 10.0 g) × 100%.
البطاقة ٢٩
السؤال
Which electrons are removed first when a transition metal forms a cation?
الإجابة
Electrons in the occupied orbital with the highest principal quantum number: 4s before 3d. For example, Fe²⁺ is [Ar] 3d⁶.
البطاقة ٣٠
السؤال
A PES spectrum has peaks proportional to 2, 2, and 6 electrons; which configuration fits?
الإجابة
1s² 2s² 2p⁶, the configuration of Ne.
البطاقة ٣١
السؤال
How does electronegativity generally change across a period and down a group?
الإجابة
It increases from left to right across a period and decreases down a group as atomic size and shielding increase.
البطاقة ٣٢
السؤال
What empirical formula results from Al³⁺ and O²⁻?
الإجابة
Al₂O₃, because two Al³⁺ ions balance three O²⁻ ions.
البطاقة ٣٣
السؤال
How does a particle's mass in atomic mass units relate to its molar mass?
الإجابة
The numerical value is the same: a molecular or formula-unit mass of x u corresponds to a molar mass of x g mol^-1.
البطاقة ٣٤
السؤال
What does the tallest isotope peak usually indicate in a simple mass spectrum?
الإجابة
The most abundant isotope, assuming comparable detection response and singly charged ions.
البطاقة ٣٥
السؤال
How much oxygen is present in 25.0 g of a compound that is 32.0% oxygen by mass?
الإجابة
8.00 g O. Multiply 25.0 g by 0.320.
البطاقة ٣٦
السؤال
What does a particle diagram with two unbonded species in changing ratios represent?
الإجابة
A mixture, because more than one particle type is present and the ratio is not fixed in a formula unit.
البطاقة ٣٧
السؤال
What distinguishes valence electrons from core electrons?
الإجابة
Valence electrons are available for bonding or ion formation; main-group valence electrons occupy the outermost shell, while transition metals may also use (n−1)d electrons. Core electrons mainly shield nuclear charge.
البطاقة ٣٨
السؤال
Why can PES peak groups reveal an atom's occupied subshells?
الإجابة
Electrons in different subshells require distinct removal energies, producing separate binding-energy groups.
البطاقة ٣٩
السؤال
How do ion radii compare with neutral atoms and within an isoelectronic series?
الإجابة
Cations are smaller than their neutral atoms, while anions are larger. Among species with the same electron count, more protons pull the electrons closer and produce the smaller radius.
البطاقة ٤٠
السؤال
What formula is expected for a compound between a Group 2 metal M and a Group 17 nonmetal X?
الإجابة
MX₂, because M forms M²⁺ and X forms X⁻.
البطاقة ٤١
السؤال
When is a covalent bond considered nonpolar?
الإجابة
When the bonded atoms have identical or very similar electronegativities, so the shared electron density is distributed approximately evenly.
البطاقة ٤٢
السؤال
Why does a bonded pair of atoms have an equilibrium bond length?
الإجابة
At that separation, attractive and repulsive interactions balance at minimum potential energy.
البطاقة ٤٣
السؤال
How are particles arranged in an ionic solid?
الإجابة
Cations and anions occupy a repeating three-dimensional lattice held by electrostatic attraction.
البطاقة ٤٤
السؤال
What model explains bonding in a metal?
الإجابة
Positive metal cores are held together by attraction to mobile, delocalized valence electrons.
البطاقة ٤٥
السؤال
How do you construct a Lewis diagram?
الإجابة
Count total valence electrons, adding electrons for a negative charge and subtracting them for a positive charge. Choose a skeleton, connect atoms with single bonds, complete terminal duets or octets, and place remaining electrons on the central atom. Add multiple bonds if needed, then check the electron total and formal charges.
البطاقة ٤٦
السؤال
What does resonance mean in a molecule or ion?
الإجابة
Resonance uses two or more valid Lewis diagrams with the same atom arrangement but different electron placement. The actual electron distribution is a hybrid; equivalent contributors have equal weight.
البطاقة ٤٧
السؤال
What determines molecular shape in VSEPR theory?
الإجابة
Electron domains around the central atom arrange to minimize repulsions.
البطاقة ٤٨
السؤال
How does an ionic bond differ from a covalent bond?
الإجابة
Ionic bonding is attraction among oppositely charged ions in an extended structure; covalent bonding uses shared electron density between atoms.
البطاقة ٤٩
السؤال
What happens to potential energy when bonded atoms are pushed much closer than equilibrium?
الإجابة
Potential energy rises sharply because nucleus–nucleus and electron–electron repulsions dominate.
البطاقة ٥٠
السؤال
Why are many ionic solids brittle?
الإجابة
A shifted lattice can align like charges, creating strong repulsion that splits the crystal.
البطاقة ٥١
السؤال
What molecular shapes arise from two electron domains with no lone pairs and from three domains with zero or one lone pair?
الإجابة
Two bonding domains give linear with a 180° angle. Three domains with no lone pairs give trigonal planar with 120° angles; replacing one bond with a lone pair gives bent with an angle slightly below 120°.
البطاقة ٥٢
السؤال
Why are metals electrically conductive as solids?
الإجابة
Their delocalized electrons can move through the solid when an electric field is applied.
البطاقة ٥٣
السؤال
How is formal charge calculated for an atom in a Lewis diagram?
الإجابة
Formal charge = valence electrons − nonbonding electrons − half the bonding electrons.
البطاقة ٥٤
السؤال
Why can't electronegativity difference alone classify a bond as ionic or covalent?
الإجابة
Bonding lies on a continuum. A larger difference means more ionic character, but the element types and especially the compound's properties give the best classification.
البطاقة ٥٥
السؤال
Which shapes and bond-angle trends arise as lone pairs replace bonds in four electron domains?
الإجابة
Four bonds give tetrahedral with ideal 109.5° angles. One lone pair gives trigonal pyramidal with smaller angles; two lone pairs give bent with typically smaller angles again because lone pairs repel more strongly than bonding pairs.
البطاقة ٥٦
السؤال
What feature of a potential-energy curve represents bond dissociation energy?
الإجابة
The energy difference from the curve's minimum to the separated-atoms limit.
البطاقة ٥٧
السؤال
When does an ionic compound conduct electricity?
الإجابة
When molten or dissolved so its ions can move; not as a rigid solid lattice.
البطاقة ٥٨
السؤال
What is a substitutional alloy?
الإجابة
An alloy in which atoms of a similar size replace some host-metal atoms in the lattice.
البطاقة ٥٩
السؤال
How do two, three, and four electron domains map to hybridization?
الإجابة
Two domains map to sp, three to sp², and four to sp³, with ideal angles of 180°, 120°, and 109.5°. Hybridization involving d orbitals is outside this deck’s scope.
البطاقة ٦٠
السؤال
What usually makes one resonance contributor more favorable than another?
الإجابة
Smaller formal-charge magnitudes, appropriate negative charge on more electronegative atoms, and complete valence shells where applicable.
البطاقة ٦١
السؤال
How many sigma and pi bonds are in single, double, and triple bonds?
الإجابة
A single bond has one sigma bond; a double has one sigma and one pi bond; a triple has one sigma and two pi bonds. Head-on sigma overlap is stronger than side-by-side pi overlap.
البطاقة ٦٢
السؤال
Why is a polar covalent bond polar?
الإجابة
Unequal electronegativity creates an uneven sharing of electron density and partial charges.
البطاقة ٦٣
السؤال
Which molecular shapes arise as lone pairs replace bonds in five electron domains?
الإجابة
Five bonds give trigonal bipyramidal; four bonds and one lone pair give seesaw; three bonds and two lone pairs give T-shaped; two bonds and three lone pairs give linear.
البطاقة ٦٤
السؤال
How do ionic charge and ionic radius affect attraction between ions?
الإجابة
Larger charge magnitudes and smaller ionic radii produce stronger attraction because the charge product increases and the ion centers are closer.
البطاقة ٦٥
السؤال
Why do ionic solids often have high melting points?
الإجابة
Many strong Coulombic attractions throughout the lattice must be overcome to free the ions.
البطاقة ٦٦
السؤال
What is an interstitial alloy?
الإجابة
A smaller atom occupies holes between host-metal atoms, often making lattice layers harder to slide.
البطاقة ٦٧
السؤال
What shape has six bonding domains and no lone pairs on the central atom?
الإجابة
Octahedral.
البطاقة ٦٨
السؤال
Which elements commonly form incomplete octets in stable Lewis diagrams?
الإجابة
Hydrogen forms a duet, and electron-deficient central atoms such as boron or beryllium can have fewer than eight electrons.
البطاقة ٦٩
السؤال
How do bond order and atomic size affect covalent bond length and strength?
الإجابة
Within a comparable bond family, higher bond order gives shorter, stronger bonds. Larger bonded atoms generally give longer bonds, which are often weaker because their orbitals overlap less effectively.
البطاقة ٧٠
السؤال
What bonding model best fits a sample that is malleable and conducts as a solid?
الإجابة
Metallic bonding with mobile, delocalized electrons and nondirectional attractions.
البطاقة ٧١
السؤال
What shape has six electron domains, five bonds, and one lone pair?
الإجابة
Square pyramidal.
البطاقة ٧٢
السؤال
Which lattice should have stronger attractions: MgO or NaCl, assuming similar separations?
الإجابة
MgO, because the charge product for Mg²⁺ and O²⁻ is larger than for Na⁺ and Cl⁻.
البطاقة ٧٣
السؤال
Why are pure metals often malleable?
الإجابة
Metal cores can shift while the mobile electron sea maintains nondirectional attraction instead of exposing fixed like-charge planes.
البطاقة ٧٤
السؤال
What is the best Lewis structure for CO₂?
الإجابة
O=C=O, with two lone pairs on each oxygen and no formal charges.
البطاقة ٧٥
السؤال
What shape has six electron domains, four bonds, and two opposite lone pairs?
الإجابة
Square planar.
البطاقة ٧٦
السؤال
What limitation does an odd total number of valence electrons create for a Lewis diagram?
الإجابة
At least one electron must remain unpaired, so not every atom can have a complete paired-electron octet.
البطاقة ٧٧
السؤال
What does a higher bond order do to a bond's potential-energy curve?
الإجابة
It generally places the minimum at a shorter internuclear distance and makes the well deeper, corresponding to a shorter bond and a larger bond-dissociation energy.
البطاقة ٧٨
السؤال
When can a carbon–carbon double bond produce geometric isomers?
الإجابة
When each carbon has two different substituents. The pi bond restricts rotation, so distinct spatial arrangements can persist.
البطاقة ٧٩
السؤال
When may a third-period central atom exceed an octet in a Lewis diagram?
الإجابة
When the valid electron count and lower formal charges favor an expanded valence shell, as in species such as SF₆.
البطاقة ٨٠
السؤال
How do you decide whether a molecule with polar bonds is polar overall?
الإجابة
Add the bond-dipole vectors using the molecular shape; symmetry may cancel them, while an asymmetric arrangement leaves a net dipole.
البطاقة ٨١
السؤال
Which interparticle forces act between all atoms and molecules?
الإجابة
London dispersion forces, caused by temporary and induced dipoles.
البطاقة ٨٢
السؤال
What four broad solid types does this deck compare?
الإجابة
Ionic, metallic, molecular, and covalent-network solids.
البطاقة ٨٣
السؤال
How do gas particles differ from liquid particles?
الإجابة
Gas particles are much farther apart and move independently; liquid particles stay close but can move past one another.
البطاقة ٨٤
السؤال
What relationship connects pressure, volume, amount, and temperature for an ideal gas?
الإجابة
PV = nRT, with absolute temperature in kelvins and units consistent with R.
البطاقة ٨٥
السؤال
What does temperature measure in kinetic molecular theory?
الإجابة
The particles' average translational kinetic energy.
البطاقة ٨٦
السؤال
What two ideal-gas assumptions fail most clearly for real gases?
الإجابة
Particles have nonzero volume and experience intermolecular attractions.
البطاقة ٨٧
السؤال
How is molarity defined?
الإجابة
Moles of solute per liter of solution: M = n/V.
البطاقة ٨٨
السؤال
What must a correct particulate diagram of NaCl(aq) show?
الإجابة
Separated Na⁺ and Cl⁻ ions in a 1:1 ratio, each surrounded by oriented water molecules.
البطاقة ٨٩
السؤال
Which separation method removes an insoluble solid from a liquid?
الإجابة
Filtration: the solid stays as residue while the liquid passes as filtrate.
البطاقة ٩٠
السؤال
What does “like dissolves like” mean at the particle level?
الإجابة
A solute tends to dissolve when new solute–solvent attractions can compete with the attractions disrupted in the pure substances.
البطاقة ٩١
السؤال
What happens when matter absorbs electromagnetic radiation?
الإجابة
Its particles move to an allowed higher-energy state when the photon energy matches the energy gap.
البطاقة ٩٢
السؤال
Which equations connect photon energy, frequency, and wavelength?
الإجابة
E = hν and c = λν.
البطاقة ٩٣
السؤال
What is the Beer–Lambert law?
الإجابة
A = εbc: absorbance equals molar absorptivity at the chosen wavelength times path length times concentration.
البطاقة ٩٤
السؤال
What molecular features generally strengthen London dispersion forces?
الإجابة
More electrons and a more polarizable cloud strengthen temporary dipoles; greater contact area and accessible π-electron density can also strengthen the attraction.
البطاقة ٩٥
السؤال
Why do molecular solids usually have low melting points and fail to conduct electricity?
الإجابة
Distinct molecules are held together by relatively weak intermolecular forces, while their valence electrons stay localized in bonds and lone pairs.
البطاقة ٩٦
السؤال
How do particles move in a solid?
الإجابة
They vibrate about fixed positions and do not translate past one another.
البطاقة ٩٧
السؤال
What graph shapes connect V or P with T(K) or n for an ideal gas?
الإجابة
All four are straight lines through the origin: V versus T(K) at fixed n and P; P versus T(K) at fixed n and V; V versus n at fixed P and T; and P versus n at fixed V and T.
البطاقة ٩٨
السؤال
At the same temperature, which gas has the greater average molecular speed: He or Xe?
الإجابة
He. Both have the same average kinetic energy, but KE = ½mv² means the lower-mass particles move faster.
البطاقة ٩٩
السؤال
Why do real gases deviate more at high pressure?
الإجابة
Particles are crowded, so their own volume is no longer negligible compared with the container volume.
البطاقة ١٠٠
السؤال
Which relationship describes dilution when solute amount is conserved?
الإجابة
M₁V₁ = M₂V₂.
البطاقة ١٠١
السؤال
Why does an aqueous ionic solution conduct electricity?
الإجابة
Dissolved ions are mobile and carry charge through the solution.
البطاقة ١٠٢
السؤال
Which property lets simple distillation separate two liquids?
الإجابة
A sufficient difference in volatility or boiling point, so the vapor is enriched in the more volatile component.
البطاقة ١٠٣
السؤال
Why are many ionic compounds soluble in water but poorly soluble in a nonpolar solvent?
الإجابة
Water can form strong ion–dipole attractions that stabilize separated ions; a nonpolar solvent cannot provide comparable attractions.
البطاقة ١٠٤
السؤال
Which molecular transition is commonly associated with microwave absorption?
الإجابة
A transition between quantized rotational energy levels.
البطاقة ١٠٥
السؤال
What frequency corresponds to a 600. nm photon?
الإجابة
5.00 × 10^14 s^-1. Use ν = c/λ with 600. nm = 6.00 × 10^-7 m.
البطاقة ١٠٦
السؤال
What is the absorbance to two significant figures when ε = 2.0 × 10² L mol^-1 cm^-1, b = 1.00 cm, and c = 0.0020 M?
الإجابة
0.40. Use A = εbc.
البطاقة ١٠٧
السؤال
What conditions allow hydrogen bonding between two molecules?
الإجابة
One molecule must donate an H covalently bonded to N, O, or F, and the other must provide a lone pair on N, O, or F. A molecule can be a donor, an acceptor, or both.
البطاقة ١٠٨
السؤال
Why are covalent-network solids often very hard with high melting points?
الإجابة
A continuous network of strong covalent bonds must be disrupted to deform or melt the solid.
البطاقة ١٠٩
السؤال
Why do a substance's solid and liquid phases usually have similar molar volumes?
الإجابة
Their particles remain in close contact in both phases, even though liquid particles can move past one another.
البطاقة ١١٠
السؤال
How is a gas mixture's total pressure related to its component pressures?
الإجابة
Ptotal = ΣPi; each partial pressure is the pressure that component would exert alone in the same volume and temperature.
البطاقة ١١١
السؤال
What microscopic events create gas pressure?
الإجابة
Gas particles collide with container walls and transfer momentum.
البطاقة ١١٢
السؤال
Why do intermolecular attractions matter more for gases at low temperature?
الإجابة
Particles move more slowly, so attractions can alter their paths and promote condensation.
البطاقة ١١٣
السؤال
What is the final concentration after 50.0 mL of 2.00 M solution is diluted to 200.0 mL?
الإجابة
0.500 M. Use M₂ = M₁V₁/V₂.
البطاقة ١١٤
السؤال
What must a particulate representation of a solution communicate?
الإجابة
The relative concentrations of its components and the particle-level interactions among those components.
البطاقة ١١٥
السؤال
What causes components to separate in chromatography?
الإجابة
They differ in attraction to the stationary phase and the mobile phase, so they travel at different rates.
البطاقة ١١٦
السؤال
Why are many polar molecular solutes soluble in water?
الإجابة
Dipole attractions or hydrogen bonds with water can replace the solute–solute and water–water attractions disrupted during mixing.
البطاقة ١١٧
السؤال
Why does an atom produce discrete spectral lines?
الإجابة
Its electrons can occupy only quantized energy levels, so only photons matching allowed energy differences are absorbed or emitted.
البطاقة ١١٨
السؤال
How does photon energy change when frequency doubles?
الإجابة
It doubles because E = hν.
البطاقة ١١٩
السؤال
Why is a calibration curve useful in spectrophotometry?
الإجابة
It relates measured absorbance to known concentrations, letting an unknown concentration be read by interpolation within the linear range.
البطاقة ١٢٠
السؤال
How does an ion–dipole attraction form, and how does it compare with dipole–dipole attraction?
الإجابة
An ion attracts the oppositely charged end of a polar molecule. Ion–dipole attractions tend to be stronger than dipole–dipole attractions.
البطاقة ١٢١
السؤال
Which solid type is usually both conductive and malleable?
الإجابة
A metallic solid, because its delocalized electrons move and its nondirectional bonding tolerates layer shifts.
البطاقة ١٢٢
السؤال
How does a crystalline solid differ from an amorphous solid?
الإجابة
A crystalline solid has long-range repeating order; an amorphous solid lacks that long-range periodic arrangement.
البطاقة ١٢٣
السؤال
How is a gas component's partial pressure found from mole fraction?
الإجابة
Pi = XiPtotal.
البطاقة ١٢٤
السؤال
How does heating a fixed-volume gas affect its pressure in the ideal model?
الإجابة
Pressure rises because faster particles collide with the walls more forcefully and frequently.
البطاقة ١٢٥
السؤال
Why can attractions make a real gas's measured pressure lower than the ideal prediction?
الإجابة
Attractions pull approaching particles away from the walls, reducing momentum transfer during wall collisions.
البطاقة ١٢٦
السؤال
How many moles of ions result from complete dissolution of 0.20 mol CaCl₂?
الإجابة
0.60 mol ions: 0.20 mol Ca²⁺ plus 0.40 mol Cl⁻.
البطاقة ١٢٧
السؤال
How should water orient around Cl⁻ in a particle model?
الإجابة
Its partially positive hydrogen ends point toward Cl⁻.
البطاقة ١٢٨
السؤال
Can filtration separate dissolved components of a liquid solution?
الإجابة
No. Dissolved particles pass through the filter with the solvent; filtration only retains an insoluble solid.
البطاقة ١٢٩
السؤال
Why do nonpolar molecular solutes often dissolve in nonpolar solvents?
الإجابة
Both rely mainly on compatible London dispersion forces, so mixing can replace the attractions disrupted in the separate substances.
البطاقة ١٣٠
السؤال
What does a shorter absorbed wavelength imply about an energy transition?
الإجابة
A larger energy gap because E = hc/λ.
البطاقة ١٣١
السؤال
What is the energy of a photon with frequency 5.0 × 10^14 s^-1?
الإجابة
3.3 × 10^-19 J. Multiply by Planck's constant: E = (6.626 × 10^-34 J·s)(5.0 × 10^14 s^-1).
البطاقة ١٣٢
السؤال
How does doubling cuvette path length affect absorbance in the linear Beer–Lambert range?
الإجابة
Absorbance doubles if concentration and molar absorptivity stay constant.
البطاقة ١٣٣
السؤال
How can noncovalent interactions affect a large biomolecule?
الإجابة
Attractions between molecules or between different regions of the same molecule help set its shape, which strongly affects its properties and function.
البطاقة ١٣٤
السؤال
Why does an ionic solid usually fail to conduct as a solid?
الإجابة
Its ions are fixed in lattice positions. The same substance conducts when molten or dissolved because the ions can then move.
البطاقة ١٣٥
السؤال
Why does a gas have no definite shape or volume?
الإجابة
Its widely spaced particles move constantly and experience minimal interparticle attraction, so they spread through the available container.
البطاقة ١٣٦
السؤال
What graph shapes show the inverse pressure–volume relationship for a fixed amount of ideal gas at constant temperature?
الإجابة
A plot of P against V is a decreasing curve, while P against 1/V is a straight line through the origin.
البطاقة ١٣٧
السؤال
At the same temperature, do different ideal gases have different average kinetic energies?
الإجابة
No. Average translational kinetic energy depends only on absolute temperature.
البطاقة ١٣٨
السؤال
Under which conditions is ideal-gas behavior most accurate?
الإجابة
Low pressure and high temperature, where particles are far apart and attractions matter least.
البطاقة ١٣٩
السؤال
What particle-level feature distinguishes a solution from a heterogeneous mixture?
الإجابة
A solution—whether solid, liquid, or gas—is uniform throughout; a heterogeneous mixture has regions or phases with different compositions.
البطاقة ١٤٠
السؤال
How should water orient around Na⁺ in a particulate model?
الإجابة
Its partially negative oxygen end points toward Na⁺.
البطاقة ١٤١
السؤال
In paper chromatography, why does one solute spot travel farther than another?
الإجابة
It interacts more strongly with the mobile phase or more weakly with the stationary phase. With known phase polarities, that travel difference can reveal relative solute polarity.
البطاقة ١٤٢
السؤال
What energy competition helps explain whether an ionic solid dissolves?
الإجابة
The energy needed to separate lattice ions competes with the energy released when ion–solvent attractions form.
البطاقة ١٤٣
السؤال
Which molecular motions commonly absorb infrared radiation?
الإجابة
Bond vibrations whose changing dipole can interact with the radiation.
البطاقة ١٤٤
السؤال
Why must wavelength be converted to meters in c = λν when c is in m s^-1?
الإجابة
Consistent units are required so meters cancel correctly and frequency comes out in s^-1.
البطاقة ١٤٥
السؤال
How can fingerprints on a cuvette affect a visible-light absorbance reading?
الإجابة
They can absorb or scatter extra light, making measured absorbance too high and the inferred concentration too high.
البطاقة ١٤٦
السؤال
What causes and controls the strength of dipole–dipole attractions?
الإجابة
Opposite partial charges on neighboring polar molecules attract. Strength increases with larger molecular dipoles and depends on how favorably the dipoles are oriented.
البطاقة ١٤٧
السؤال
Why is graphite conductive and soft while diamond is insulating and hard?
الإجابة
Graphite has delocalized electrons within its sheets, so it conducts, and its layers can slide, so it is soft. Diamond has a rigid three-dimensional network of localized covalent bonds, making it hard and insulating.
البطاقة ١٤٨
السؤال
Why are gases much more compressible than liquids?
الإجابة
Gas particles have large empty spaces between them; liquid particles are already close together.
البطاقة ١٤٩
السؤال
What volume does 0.500 mol CO₂ occupy at 1.00 atm and 300. K if it behaves ideally?
الإجابة
12.3 L. Use V = nRT/P = (0.500 mol)(0.08206 L atm mol^-1 K^-1)(300. K)/(1.00 atm).
البطاقة ١٥٠
السؤال
Why does a lighter gas effuse faster than a heavier gas at the same temperature?
الإجابة
Its particles have a higher average speed because equal average kinetic energy is shared by less mass.
البطاقة ١٥١
السؤال
How does finite particle volume affect a real gas at very high pressure?
الإجابة
The free volume available for particle motion is smaller than the container volume assumed by the ideal model.
البطاقة ١٥٢
السؤال
How should 250.0 mL of 0.100 M NaCl be prepared from solid NaCl?
الإجابة
Dissolve 0.0250 mol NaCl, or 1.46 g, then dilute to exactly 250.0 mL in a volumetric flask.
البطاقة ١٥٣
السؤال
What changes in a particle diagram when a solution is diluted without losing solute?
الإجابة
The solute-particle count stays constant while solvent volume and particle spacing increase.
البطاقة ١٥٤
السؤال
Why is fractional distillation better than simple distillation for liquids with close boiling points?
الإجابة
Repeated vaporization–condensation steps enrich the vapor in the more volatile component more effectively.
البطاقة ١٥٥
السؤال
Why are oil and water usually immiscible?
الإجابة
Water's strong hydrogen-bond network isn't replaced by equally strong water–oil attractions, so the substances separate into phases.
البطاقة ١٥٦
السؤال
Which molecular transition is commonly associated with ultraviolet or visible absorption?
الإجابة
A transition between electronic energy levels.
البطاقة ١٥٧
السؤال
Which photon carries more energy, blue light or red light?
الإجابة
Blue light, because it has shorter wavelength and higher frequency.
البطاقة ١٥٨
السؤال
Why is absorbance often measured at the wavelength of maximum absorbance in Beer–Lambert analysis?
الإجابة
It gives the largest concentration-sensitive signal, and the flat top near the maximum makes small wavelength-setting errors less influential.
البطاقة ١٥٩
السؤال
What creates a dipole–induced-dipole attraction, and what controls its strength?
الإجابة
A permanent dipole distorts a nearby nonpolar particle's electron cloud and creates an attractive temporary dipole. A larger permanent dipole and a more polarizable nonpolar partner make the attraction stronger.
البطاقة ١٦٠
السؤال
How do stronger intermolecular forces affect vapor pressure, boiling point, and melting point?
الإجابة
They lower vapor pressure and raise boiling point. Melting point often rises too, but the trend is less direct because melting rearranges rather than fully separates particles.
البطاقة ١٦١
السؤال
How do particles behave in a liquid?
الإجابة
They stay in close contact while moving and colliding continuously. Temperature and interparticle attractions affect their arrangement and motion.
البطاقة ١٦٢
السؤال
Why must Celsius temperature be converted to kelvins in gas-law calculations?
الإجابة
Gas-law proportionalities require an absolute temperature scale whose zero corresponds to zero extrapolated thermal motion.
البطاقة ١٦٣
السؤال
How does raising temperature change a Maxwell–Boltzmann speed distribution?
الإجابة
The distribution broadens, its peak lowers and shifts right, and a larger fraction of particles have high speed.
البطاقة ١٦٤
السؤال
Why does the ideal-gas model treat collisions as elastic?
الإجابة
It assumes total kinetic energy is conserved in particle–particle and particle–wall collisions.
البطاقة ١٦٥
السؤال
How many moles of solute are in 75.0 mL of a 0.400 M solution?
الإجابة
0.0300 mol. Multiply 0.400 mol L^-1 by 0.0750 L.
البطاقة ١٦٦
السؤال
For equal solution volumes drawn at the same scale, what shows which solution is more concentrated?
الإجابة
The more concentrated diagram contains more solute particles in that equal volume.
البطاقة ١٦٧
السؤال
How do differences in intermolecular attractions let distillation separate a liquid solution?
الإجابة
They give the components different vapor pressures, so the vapor is enriched in the more volatile component.
البطاقة ١٦٨
السؤال
What comparison helps predict whether two liquids will be miscible?
الإجابة
Liquids with similar types and strengths of intermolecular attractions are more likely to mix uniformly.
البطاقة ١٦٩
السؤال
How can an absorption spectrum help identify a substance?
الإجابة
Its allowed energy gaps produce a characteristic pattern of absorbed wavelengths that can be compared with known spectra.
البطاقة ١٧٠
السؤال
How does absorbing or emitting a photon change an atom's or molecule's energy?
الإجابة
Absorption raises the species' energy by exactly the photon energy; emission lowers it by the same amount.
البطاقة ١٧١
السؤال
What macroscopic evidence can support that a chemical reaction occurred?
الإجابة
Evidence can include gas formation, precipitate formation, a persistent color change, or an energy change, interpreted with particle-level changes.
البطاقة ١٧٢
السؤال
What does a net ionic equation include?
الإجابة
Only the dissolved or reacting species that undergo chemical change; spectator ions are omitted.
البطاقة ١٧٣
السؤال
What must a correct particulate reaction diagram conserve?
الإجابة
The number of atoms of every element and the total charge.
البطاقة ١٧٤
السؤال
What distinguishes a chemical change from a physical change?
الإجابة
A chemical change rearranges bonds into new substances; a physical change alters state or arrangement without changing chemical identity.
البطاقة ١٧٥
السؤال
What does a balanced equation's coefficient ratio provide?
الإجابة
The mole ratio among reacting and produced species.
البطاقة ١٧٦
السؤال
What is the equivalence point of a titration?
الإجابة
The point where titrant and analyte have reacted in the stoichiometric ratio given by the balanced equation.
البطاقة ١٧٧
السؤال
What defines a precipitation reaction?
الإجابة
Aqueous ions combine to form a sparingly soluble solid.
البطاقة ١٧٨
السؤال
What happens in a Brønsted–Lowry acid–base reaction?
الإجابة
A proton transfers from the acid (donor) to the base (acceptor). In aqueous solution, H₂O can play either role.
البطاقة ١٧٩
السؤال
What does oxidation mean in a redox reaction?
الإجابة
Loss of electrons and an increase in oxidation number.
البطاقة ١٨٠
السؤال
What particle-level change confirms that a process is chemical?
الإجابة
Atoms rearrange into new combinations, producing substances with different compositions.
البطاقة ١٨١
السؤال
Which ions are spectators when AgNO₃(aq) reacts with NaCl(aq)?
الإجابة
Na⁺ and NO₃⁻. The net ionic reaction is Ag⁺(aq) + Cl⁻(aq) → AgCl(s).
البطاقة ١٨٢
السؤال
How does a particulate diagram reveal the limiting reactant?
الإجابة
After forming the maximum product allowed by the ratio, none of the limiting reactant remains while excess reactant particles do.
البطاقة ١٨٣
السؤال
Is melting ice a chemical or physical change?
الإجابة
A physical change. H₂O molecules remain H₂O while their arrangement and motion change.
البطاقة ١٨٤
السؤال
How is the limiting reactant identified from given amounts?
الإجابة
Convert each reactant to the same product amount using the balanced equation; the smaller product amount identifies the limiting reactant.
البطاقة ١٨٥
السؤال
How does an endpoint differ from an equivalence point?
الإجابة
The endpoint is an observed signal such as indicator color change; the equivalence point is the exact stoichiometric condition.
البطاقة ١٨٦
السؤال
How is complete combustion of a hydrocarbon in excess oxygen classified, and what products form?
الإجابة
It is a redox combustion reaction that forms CO₂ and H₂O.
البطاقة ١٨٧
السؤال
What are the conjugate acid and conjugate base in NH₃ + H₂O ⇌ NH₄⁺ + OH⁻?
الإجابة
NH₄⁺ is the conjugate acid of NH₃, and OH⁻ is the conjugate base of H₂O.
البطاقة ١٨٨
السؤال
What does reduction mean in a redox reaction?
الإجابة
Gain of electrons and a decrease in oxidation number.
البطاقة ١٨٩
السؤال
Which common changes are physical rather than chemical?
الإجابة
Phase changes and the formation or separation of mixtures are physical when each substance keeps its composition.
البطاقة ١٩٠
السؤال
How are strong soluble electrolytes written in a complete ionic equation?
الإجابة
As separated aqueous ions; solids, liquids, gases, and weak electrolytes stay intact.
البطاقة ١٩١
السؤال
A diagram starts with six A particles and four B₂ particles for 2A + B₂ → 2AB; what remains after completion?
الإجابة
One B₂ remains. Six A consume three B₂ and form six AB.
البطاقة ١٩٢
السؤال
Why is dissolving NaCl in water normally classified as a physical change?
الإجابة
Na⁺ and Cl⁻ separate and become hydrated, but retain their chemical identities. Removing the water recovers NaCl; the shift from ion–ion to ion–dipole attractions does not by itself form a new substance.
البطاقة ١٩٣
السؤال
What mass of AgCl can form from 25.0 mL of 0.200 M AgNO₃ mixed with excess Cl⁻?
الإجابة
0.717 g AgCl. The 1:1 reaction gives 0.00500 mol AgCl; multiply by 143.32 g mol^-1.
البطاقة ١٩٤
السؤال
What calculation finds unknown analyte moles at equivalence?
الإجابة
Use titrant moles, n = MV, then apply the balanced-reaction mole ratio.
البطاقة ١٩٥
السؤال
Which feature identifies an acid–base, redox, or precipitation reaction?
الإجابة
Acid–base reactions transfer protons, redox reactions change oxidation numbers through electron transfer, and precipitation reactions form a sparingly soluble solid.
البطاقة ١٩٦
السؤال
What is the net ionic equation for strong acid–strong base neutralization?
الإجابة
H⁺(aq) + OH⁻(aq) → H₂O(l).
البطاقة ١٩٧
السؤال
What is the oxidation number of sulfur in SO₄²⁻?
الإجابة
+6. Four oxygens contribute -8 total, so sulfur must be +6 to give -2 overall.
البطاقة ١٩٨
السؤال
Why can gas bubbles alone be ambiguous evidence of reaction?
الإجابة
Bubbles may also come from boiling or dissolved gas escaping, so the context and particle identities must support a chemical change.
البطاقة ١٩٩
السؤال
How is melting ice represented as a balanced physical-change equation?
الإجابة
H₂O(s) → H₂O(l). The formula and atom count stay the same because only the physical state changes.
البطاقة ٢٠٠
السؤال
What does a particle diagram show when no reaction occurs after two aqueous ionic solutions mix?
الإجابة
All ions remain separated and solvated, with no new bonded particles, precipitate, or gas.
البطاقة ٢٠١
السؤال
Why is rusting iron a chemical change?
الإجابة
Iron atoms form new iron-oxide substances through electron transfer and new bonding.
البطاقة ٢٠٢
السؤال
For 2H₂O₂(aq) → 2H₂O(l) + O₂(g), what volume of O₂ forms from 0.100 mol H₂O₂ at 298 K and 1.00 atm?
الإجابة
1.22 L O₂. The mole ratio gives 0.0500 mol O₂, then V = nRT/P.
البطاقة ٢٠٣
السؤال
A 25.0 mL monoprotic acid sample requires 20.0 mL of 0.150 M NaOH; what is the acid concentration?
الإجابة
0.120 M. At 1:1 equivalence, moles acid = 0.0200 L × 0.150 M, then divide by 0.0250 L.
البطاقة ٢٠٤
السؤال
Which salts does the minimum solubility rule in this deck treat as soluble?
الإجابة
All salts containing Na⁺, K⁺, NH₄⁺, or NO₃⁻ are treated as soluble in water.
البطاقة ٢٠٥
السؤال
How are the strengths of a conjugate acid and its conjugate base related?
الإجابة
A stronger acid has a weaker conjugate base, and a stronger base has a weaker conjugate acid.
البطاقة ٢٠٦
السؤال
How are oxidation and reduction half-reactions combined into one balanced equation?
الإجابة
Multiply them so electrons lost equal electrons gained, add the half-reactions, then cancel electrons and any identical species on both sides.
البطاقة ٢٠٧
السؤال
How do molecular, complete ionic, and net ionic equations differ?
الإجابة
Molecular equations keep compounds intact, complete ionic equations split strong soluble electrolytes, and net ionic equations remove spectators. All three conserve atoms and charge.
البطاقة ٢٠٨
السؤال
How should coefficients change particle counts in a reaction diagram?
الإجابة
They set whole-particle ratios while preserving each particle's chemical formula.
البطاقة ٢٠٩
السؤال
Is separating a mixture by distillation a chemical or physical change?
الإجابة
A physical change. Components change phase and location but keep their chemical identities.
البطاقة ٢١٠
السؤال
What equation results from Cu → Cu²⁺ + 2e⁻ and Ag⁺ + e⁻ → Ag?
الإجابة
Cu + 2Ag⁺ → Cu²⁺ + 2Ag. Multiply the silver half-reaction by 2 and cancel 2e⁻; both atom counts and net charge then match.
البطاقة ٢١١
السؤال
How is average reaction rate found from a reactant concentration?
الإجابة
Use the negative concentration change divided by elapsed time, adjusted by its stoichiometric coefficient when comparing species rates.
البطاقة ٢١٢
السؤال
What does a rate law express?
الإجابة
It shows how the measured rate depends on reactant concentrations. In rate = k[A]^m[B]^n, m and n are the orders in A and B, and m + n is the overall order.
البطاقة ٢١٣
السؤال
A plot of ln[A] versus time is linear; what is the order in A and its integrated rate law?
الإجابة
First order: ln[A]t = ln[A]0 − kt, so the plot's slope is −k.
البطاقة ٢١٤
السؤال
What is an elementary reaction?
الإجابة
A single step in a mechanism whose rate law follows directly from its reactant molecularity.
البطاقة ٢١٥
السؤال
What two collision conditions are needed for reaction?
الإجابة
Sufficient collision energy and a productive molecular orientation.
البطاقة ٢١٦
السؤال
What does activation energy represent on a reaction-energy profile?
الإجابة
The energy difference from the reactants to the transition state. The reaction coordinate tracks the step's structural progress, not elapsed time.
البطاقة ٢١٧
السؤال
What must the elementary steps of a valid mechanism do when added?
الإجابة
Cancel intermediates and reproduce the overall balanced reaction.
البطاقة ٢١٨
السؤال
How is a proposed mechanism tested against kinetics?
الإجابة
Its derived rate law must agree with the experimentally measured rate law.
البطاقة ٢١٩
السؤال
What does a pre-equilibrium approximation assume?
الإجابة
A fast reversible step reaches equilibrium before a later slow step consumes its intermediate.
البطاقة ٢٢٠
السؤال
What does each peak on a multistep energy profile represent?
الإجابة
A transition state for one elementary step.
البطاقة ٢٢١
السؤال
How does a catalyst increase reaction rate?
الإجابة
It provides an alternate mechanism with a lower activation-energy pathway.
البطاقة ٢٢٢
السؤال
Why does crushing a solid reactant usually increase its reaction rate?
الإجابة
Crushing increases exposed surface area, so more reactant particles can collide with the other reactant each second.
البطاقة ٢٢٣
السؤال
How is reaction order found from initial-rate data?
الإجابة
Compare trials where one reactant concentration changes while the others stay constant, then match the rate factor to the concentration factor.
البطاقة ٢٢٤
السؤال
A plot of [A] versus time is linear; what is the order in A and its integrated rate law?
الإجابة
Zero order: [A]t = [A]0 − kt, so the plot's slope is −k.
البطاقة ٢٢٥
السؤال
What is the rate law for the elementary step 2A + B → products?
الإجابة
rate = k[A]²[B]. This inference is valid because the step is elementary.
٤٥٠ بطاقة
Advanced High School Chemistry Flashcards: Complete 9-Part Course Review
ادرس هذه الرزمة مجانًا
سيفتح تطبيق Flashcards لتبدأ الدراسة.
البطاقة ٢٢٦
السؤال
How does raising temperature change a Maxwell–Boltzmann energy distribution and reaction rate?
الإجابة
The distribution shifts and broadens toward higher energies, so a larger fraction of collisions exceeds the activation-energy threshold and can react.
البطاقة ٢٢٧
السؤال
How is ΔH read from a reaction-energy profile?
الإجابة
ΔH = energy of products − energy of reactants.
البطاقة ٢٢٨
السؤال
What is a reaction intermediate?
الإجابة
A species formed in one mechanism step and consumed in a later step, so it cancels from the overall equation.
البطاقة ٢٢٩
السؤال
Why can't overall reaction coefficients usually supply rate-law exponents?
الإجابة
The overall equation hides the mechanism; exponents come from experiment unless the reaction is a stated elementary step.
البطاقة ٢٣٠
السؤال
How does pre-equilibrium remove an intermediate from a rate law?
الإجابة
Use the fast-step equilibrium relation to express the intermediate concentration in terms of stable reactants.
البطاقة ٢٣١
السؤال
What does each valley between peaks represent on a multistep profile?
الإجابة
A reaction intermediate.
البطاقة ٢٣٢
السؤال
Does a catalyst change ΔH or the equilibrium constant?
الإجابة
No. It changes the pathway and rates, not reactant/product energies or the equilibrium composition.
البطاقة ٢٣٣
السؤال
For 2A → B, how are disappearance of A and appearance of B related?
الإجابة
Reaction rate = -(1/2)Δ[A]/Δt = Δ[B]/Δt.
البطاقة ٢٣٤
السؤال
How do the units of k depend on a rate law's overall order?
الإجابة
They must make the rate unit M s^-1: zero order uses M s^-1, first order s^-1, and second order M^-1 s^-1.
البطاقة ٢٣٥
السؤال
A plot of 1/[A] versus time is linear; what is the order in A and its integrated rate law?
الإجابة
Second order: 1/[A]t = 1/[A]0 + kt, so the plot's slope is +k.
البطاقة ٢٣٦
السؤال
What is molecularity?
الإجابة
The number of reacting particles in an elementary step, such as unimolecular or bimolecular.
البطاقة ٢٣٧
السؤال
How does raising temperature affect k in the qualitative Arrhenius model?
الإجابة
k increases, often sharply, because a larger fraction of collisions can reach the transition state. Arrhenius-equation calculations are outside this deck’s scope.
البطاقة ٢٣٨
السؤال
A reactant falls from 0.80 M to 0.50 M in 30. s; what is its average disappearance rate to two significant figures?
الإجابة
0.010 M s^-1. Use -(0.50 − 0.80) M ÷ 30. s.
البطاقة ٢٣٩
السؤال
How does a catalyst differ from an intermediate in a mechanism?
الإجابة
A catalyst is consumed early and regenerated later; an intermediate is formed early and consumed later.
البطاقة ٢٤٠
السؤال
For 2NO₂ → NO₃ + NO (slow), followed by NO₃ + CO → NO₂ + CO₂ (fast), what rate law is predicted?
الإجابة
rate = k[NO₂]². The first step is elementary and rate-limiting, so its molecularity sets the observed rate law.
البطاقة ٢٤١
السؤال
On a multistep reaction-energy profile, which feature often identifies the rate-determining step?
الإجابة
The step with the largest activation barrier measured from its preceding valley to its peak.
البطاقة ٢٤٢
السؤال
If changing [B] leaves rate unchanged, what is the order in B?
الإجابة
Zero order, so [B]^0 = 1 in the measured rate law.
البطاقة ٢٤٣
السؤال
What mechanism changes can binding, acid–base, or surface catalysis introduce?
الإجابة
They can orient reactants, lower activation barriers, or create new bound, protonated, or deprotonated intermediates and elementary steps; the catalyst is regenerated.
البطاقة ٢٤٤
السؤال
What is special about a first-order reaction's half-life?
الإجابة
It is constant and independent of starting concentration: t1/2 = ln 2/k. Radioactive decay is a common first-order example.
البطاقة ٢٤٥
السؤال
Why is a termolecular elementary collision uncommon?
الإجابة
Three particles must collide simultaneously with suitable energy and orientation, which is much less probable than one- or two-particle events.
البطاقة ٢٤٦
السؤال
On a reaction-energy profile, how are reverse activation energy, forward activation energy, and ΔH related?
الإجابة
Ea,reverse = Ea,forward − ΔH. The reverse barrier is measured from products to the same transition state.
البطاقة ٢٤٧
السؤال
Why can correct orientation matter even above the activation energy?
الإجابة
The colliding reactive sites must align so old bonds can break and new bonds can form along the reaction pathway.
البطاقة ٢٤٨
السؤال
How does detecting a proposed reaction intermediate affect a mechanism claim?
الإجابة
It supports a mechanism that contains that intermediate, but it doesn't prove that mechanism is unique.
البطاقة ٢٤٩
السؤال
For 2NO ⇌ N₂O₂ (fast equilibrium), followed by N₂O₂ + O₂ → 2NO₂ (slow), what observed rate law results?
الإجابة
rate = kobs[NO]²[O₂]. Start with rate = k₂[N₂O₂][O₂], use [N₂O₂] = K[NO]² from the fast equilibrium, then substitute.
البطاقة ٢٥٠
السؤال
What does the highest point of a one-step energy profile represent?
الإجابة
The transition state, an unstable arrangement at the top of the activation barrier.
البطاقة ٢٥١
السؤال
What sign does q have for an endothermic system?
الإجابة
Positive, because the system absorbs heat from the surroundings.
البطاقة ٢٥٢
السؤال
How does an exothermic reaction appear on an enthalpy diagram?
الإجابة
Products lie below reactants, so ΔH is negative.
البطاقة ٢٥٣
السؤال
What condition defines thermal equilibrium?
الإجابة
Objects in contact have the same temperature, so there is no net heat transfer.
البطاقة ٢٥٤
السؤال
What equations relate heat capacity and temperature change to heat transfer?
الإجابة
Use q = mcΔT with specific heat capacity, or q = nCₘΔT with molar heat capacity.
البطاقة ٢٥٥
السؤال
Why is temperature constant during a phase-change plateau?
الإجابة
Added or removed energy changes interparticle potential energy instead of average kinetic energy.
البطاقة ٢٥٦
السؤال
What does ΔHrxn describe?
الإجابة
The heat absorbed or released at constant pressure for the reaction exactly as written under the stated conditions.
البطاقة ٢٥٧
السؤال
How is reaction enthalpy estimated from average bond enthalpies?
الإجابة
ΔHrxn ≈ Σ(bonds broken) − Σ(bonds formed).
البطاقة ٢٥٨
السؤال
What is the standard enthalpy of formation of an element in its standard state?
الإجابة
Zero by definition.
البطاقة ٢٥٩
السؤال
In a Hess’s law calculation, how should a step change when the target needs twice its reverse?
الإجابة
Reverse the equation, double every coefficient, and multiply its ΔH by -2.
البطاقة ٢٦٠
السؤال
How can energy cross a system boundary during a process?
الإجابة
As heat or work. Heat transferred to or work done on the system increases its energy; heat transferred from or work done by the system decreases it.
البطاقة ٢٦١
السؤال
How does an endothermic reaction appear on an enthalpy diagram?
الإجابة
Products lie above reactants, so ΔH is positive.
البطاقة ٢٦٢
السؤال
How are heat gained by a system and heat lost by its surroundings related in an isolated setup?
الإجابة
qsystem = -qsurroundings.
البطاقة ٢٦٣
السؤال
In coffee-cup calorimetry, how is reaction heat related to solution heat?
الإجابة
qrxn = -qsolution when calorimeter heat is negligible and pressure is constant.
البطاقة ٢٦٤
السؤال
What heat is required to melt n moles at the melting point?
الإجابة
q = nΔHfus.
البطاقة ٢٦٥
السؤال
How does reversing a reaction change ΔH?
الإجابة
It reverses the sign of ΔH.
البطاقة ٢٦٦
السؤال
Why is breaking a bond endothermic?
الإجابة
Energy must be supplied to separate atoms against their bonding attraction.
البطاقة ٢٦٧
السؤال
How is ΔH°rxn calculated from standard enthalpies of formation?
الإجابة
ΣνΔHf°(products) − ΣνΔHf°(reactants).
البطاقة ٢٦٨
السؤال
How does multiplying an equation by 3 affect its ΔH?
الإجابة
Multiply ΔH by 3 because enthalpy change scales with reaction amount.
البطاقة ٢٦٩
السؤال
Why can an exothermic dissolution warm the solution?
الإجابة
The solution warms because forming solute–solvent attractions releases more energy than is absorbed in separating the original particles. The net potential-energy decrease raises particle kinetic energy and temperature.
البطاقة ٢٧٠
السؤال
Does an energy diagram's activation barrier determine ΔH?
الإجابة
No. ΔH depends on reactant and product energy levels, while the barrier controls kinetics.
البطاقة ٢٧١
السؤال
Why does heat flow from a warmer object to a cooler object?
الإجابة
Energy transfers through collisions until their average kinetic energies, and therefore temperatures, equalize.
البطاقة ٢٧٢
السؤال
How much heat warms 100.0 g of water by 5.0°C?
الإجابة
2.1 kJ. Use q = (100.0 g)(4.184 J g^-1 °C^-1)(5.0°C).
البطاقة ٢٧٣
السؤال
How are the molar enthalpies of a phase change and its reverse related?
الإجابة
They have equal magnitudes and opposite signs, such as ΔHcond = -ΔHvap and ΔHfreeze = -ΔHfus.
البطاقة ٢٧٤
السؤال
How does doubling every coefficient in a thermochemical equation affect ΔH?
الإجابة
It doubles ΔH.
البطاقة ٢٧٥
السؤال
Why is forming a bond exothermic?
الإجابة
Atoms move to a lower-potential-energy bonded arrangement and release energy.
البطاقة ٢٧٦
السؤال
What formation equation defines ΔHf° for CO₂(g)?
الإجابة
C(s, graphite) + O₂(g) → CO₂(g), forming exactly one mole from elements in standard states.
البطاقة ٢٧٧
السؤال
What should happen to intermediate species when equations in a Hess’s law calculation are added?
الإجابة
They cancel, leaving the target overall reaction.
البطاقة ٢٧٨
السؤال
If the surroundings warm during a process, what is the likely sign of qsystem?
الإجابة
Negative; the system likely released heat to the surroundings.
البطاقة ٢٧٩
السؤال
For a profile with reactants at 40 kJ and products at 10 kJ, what is ΔH?
الإجابة
-30 kJ for the reaction as drawn.
البطاقة ٢٨٠
السؤال
Assuming no phase change, what determines the final temperature when two substances exchange heat in an insulated container?
الإجابة
Energy conservation: q_warm + q_cool = 0. Use each substance's mass, heat capacity, and initial temperature to solve for the common final temperature.
البطاقة ٢٨١
السؤال
How would heat loss to the room affect an exothermic calorimetry result?
الإجابة
The observed temperature rise is too small, so the calculated magnitude of released heat is too low.
البطاقة ٢٨٢
السؤال
What heat expression covers warming a liquid without a phase change?
الإجابة
q = mcΔT, not nΔHphase.
البطاقة ٢٨٣
السؤال
If forming 1 mol of product has ΔH = -50 kJ mol^-1, what is q when 2 mol forms?
الإجابة
-100 kJ. Use q = nΔH = (2 mol)(-50 kJ mol^-1).
البطاقة ٢٨٤
السؤال
Breaking reactant bonds requires 500 kJ, and forming product bonds releases 650 kJ; what is the estimated ΔH?
الإجابة
-150 kJ, from 500 − 650.
البطاقة ٢٨٥
السؤال
For CO(g) + ½O₂(g) → CO₂(g), what is ΔH°rxn if ΔHf°[CO] = -110.5 and ΔHf°[CO₂] = -393.5 kJ mol^-1?
الإجابة
-283.0 kJ. Use -393.5 - [-110.5 + ½(0)], since ΔHf°[O₂(g)] = 0.
البطاقة ٢٨٦
السؤال
In a Hess’s law calculation, two valid steps have ΔH values +25 kJ and -60 kJ; what is the combined ΔH?
الإجابة
-35 kJ, provided the equations add to the target reaction.
البطاقة ٢٨٧
السؤال
Why is “bonds breaking releases energy” incorrect?
الإجابة
Bond breaking absorbs energy; the overall reaction releases energy only when forming new bonds releases more than breaking old bonds requires.
البطاقة ٢٨٨
السؤال
How would melting appear on an energy diagram?
الإجابة
The liquid lies above the solid, so ΔHfus is positive; the diagram represents a physical, endothermic change.
البطاقة ٢٨٩
السؤال
Can two objects at the same temperature exchange energy microscopically?
الإجابة
Yes, but their energy transfers balance, so there is no net heat flow.
البطاقة ٢٩٠
السؤال
Why must the calorimeter's heat capacity be included when it isn't negligible?
الإجابة
The apparatus can absorb or release heat, so include q_cal = C_calΔT in the energy balance: q_process + q_solution + q_cal = 0.
البطاقة ٢٩١
السؤال
What makes chemical equilibrium dynamic?
الإجابة
Forward and reverse reactions continue at equal rates even though macroscopic concentrations stay constant.
البطاقة ٢٩٢
السؤال
For aA + bB ⇌ cC, what is the concentration-form expression for Q?
الإجابة
Q = [C]^c / ([A]^a[B]^b), using current rather than necessarily equilibrium concentrations.
البطاقة ٢٩٣
السؤال
What does K much greater than 1 indicate?
الإجابة
Products predominate at equilibrium, though K says nothing about reaction speed.
البطاقة ٢٩٤
السؤال
How does reversing a reaction change its equilibrium constant?
الإجابة
K becomes 1/K.
البطاقة ٢٩٥
السؤال
Can a reversible system reach equilibrium when it starts with only products?
الإجابة
Yes, if the reverse reaction is possible. The equilibrium composition depends on temperature, initial amounts, and volume or pressure.
البطاقة ٢٩٦
السؤال
How do Q and K predict reaction direction?
الإجابة
Q < K shifts forward, Q > K shifts reverse, and Q = K means equilibrium.
البطاقة ٢٩٧
السؤال
Which species are omitted from a heterogeneous equilibrium expression?
الإجابة
Pure solids and pure liquids because their activities are effectively constant.
البطاقة ٢٩٨
السؤال
How does increasing a dissolved reactant's concentration or a gaseous reactant's partial pressure affect equilibrium at constant temperature when other Q terms are initially unchanged?
الإجابة
It lowers Q relative to K, so the system shifts toward products until Q = K again. Changing the amount of a pure solid or liquid omitted from Q does not cause this shift while that pure phase remains present.
البطاقة ٢٩٩
السؤال
What does a flat concentration-time graph mean at equilibrium?
الإجابة
Each concentration is constant, not necessarily equal to the others.
البطاقة ٣٠٠
السؤال
For A ⇌ B in one fixed volume, a particulate model shows 16 A and 0 B initially, then 4 A and 12 B at equilibrium. What changed, what predominates, and what is Kc?
الإجابة
The net change was forward: 12 A particles became 12 B particles. B predominates at equilibrium, and Kc = [B]/[A] = 12/4 = 3.0 because both counts come from the same fixed volume.
البطاقة ٣٠١
السؤال
What can Ksp tell you about a salt's solubility, and when can two Ksp values be compared directly?
الإجابة
Ksp > 1 indicates a soluble salt. For salts with the same dissolution stoichiometry, a larger Ksp generally means greater molar solubility; across different stoichiometries, calculate molar solubility before comparing.
البطاقة ٣٠٢
السؤال
What is the common-ion effect on solubility?
الإجابة
Adding an ion already in the dissolution equilibrium usually decreases the solid's molar solubility.
البطاقة ٣٠٣
السؤال
How does uniform dilution shift an aqueous equilibrium based on the stoichiometric powers in Q?
الإجابة
It shifts toward the side with the larger sum of stoichiometric coefficients for dissolved species included in Q. If the sums are equal, dilution causes no shift by this effect; pure solids and liquids remain omitted.
البطاقة ٣٠٤
السؤال
What happens if a reversible reaction starts with reactants only?
الإجابة
The forward rate is initially largest; products form, the reverse rate grows, and the rates eventually become equal.
البطاقة ٣٠٥
السؤال
What is the purpose of an ICE table?
الإجابة
To organize initial, change, and equilibrium concentrations using reaction stoichiometry.
البطاقة ٣٠٦
السؤال
Can a reaction with a very large K be slow?
الإجابة
Yes. K describes thermodynamic equilibrium position, while rate depends on kinetics and activation energy.
البطاقة ٣٠٧
السؤال
What happens to Q immediately after product concentration increases?
الإجابة
Q increases; if it rises above K, the reaction shifts toward reactants.
البطاقة ٣٠٨
السؤال
How does multiplying every reaction coefficient by 2 affect K?
الإجابة
The new equilibrium constant is K².
البطاقة ٣٠٩
السؤال
For A ⇌ B, Kc = 4.0 and initially [A] = 1.0 M and [B] = 0, what are the equilibrium concentrations?
الإجابة
[A] = 0.20 M and [B] = 0.80 M. Let x form: Kc = x/(1.0 − x) = 4.0, so x = 0.80 M.
البطاقة ٣١٠
السؤال
What macroscopic properties stay constant at equilibrium?
الإجابة
Properties such as concentration, color, and pressure remain constant when external conditions are fixed.
البطاقة ٣١١
السؤال
How does decreasing volume shift a gaseous equilibrium?
الإجابة
Toward the side with fewer moles of gas, if the two sides have different gaseous mole counts.
البطاقة ٣١٢
السؤال
For N₂ + 3H₂ ⇌ 2NH₃, what is Kc?
الإجابة
Kc = [NH₃]² / ([N₂][H₂]³).
البطاقة ٣١٣
السؤال
For CaF₂(s) ⇌ Ca²⁺ + 2F⁻, how is Ksp written in terms of molar solubility s in pure water?
الإجابة
Ksp = s(2s)² = 4s³ because [Ca²⁺] = s and [F⁻] = 2s.
البطاقة ٣١٤
السؤال
What does K much less than 1 indicate?
الإجابة
Reactants predominate at equilibrium.
البطاقة ٣١٥
السؤال
How does decreasing a dissolved product's concentration or a gaseous product's partial pressure affect equilibrium when other Q terms are initially unchanged?
الإجابة
It lowers Q and drives a net forward reaction until equilibrium returns. Changing the amount of a pure solid or liquid omitted from Q does not cause this shift while that phase remains.
البطاقة ٣١٦
السؤال
Does equilibrium mean the reaction has stopped?
الإجابة
No. Both directions continue, but equal rates produce no net macroscopic change.
البطاقة ٣١٧
السؤال
Why does adding NaF reduce CaF₂ solubility?
الإجابة
The added F⁻ raises Qsp, shifting the dissolution equilibrium toward solid CaF₂.
البطاقة ٣١٨
السؤال
For N₂ + 3H₂ ⇌ 2NH₃, what is Kp when P_N₂ = 0.50 atm, P_H₂ = 1.50 atm, and P_NH₃ = 0.25 atm?
الإجابة
0.037. Use Kp = (P_NH₃)²/[(P_N₂)(P_H₂)³] = (0.25)²/[(0.50)(1.50)³]. Use equilibrium partial pressures directly; Kc↔Kp conversion isn't assessed.
البطاقة ٣١٩
السؤال
What happens to Q when a gaseous equilibrium mixture is compressed at constant temperature if products have fewer gas moles?
الإجابة
Q falls relative to K, so the reaction shifts toward products.
البطاقة ٣٢٠
السؤال
How do K and Q transform when a reaction is reversed, its coefficients are multiplied, or reactions are added?
الإجابة
They follow the same algebra: reversing takes the reciprocal, multiplying every coefficient by c raises the value to the power c, and adding reactions multiplies their K or Q values.
البطاقة ٣٢١
السؤال
When is the small-x approximation acceptable?
الإجابة
When x is small relative to the initial concentration and the final result confirms the neglected change is suitably small.
البطاقة ٣٢٢
السؤال
What graph feature shows a disturbance followed by re-equilibration?
الإجابة
A sudden or gradual concentration change followed by new constant plateaus while rates return to equality.
البطاقة ٣٢٣
السؤال
If Q = 0.20 and K = 5.0, which direction is favored next?
الإجابة
Forward, because Q < K.
البطاقة ٣٢٤
السؤال
At equilibrium, are reactant and product concentrations equal?
الإجابة
Not necessarily. They are constant, while forward and reverse rates are equal.
البطاقة ٣٢٥
السؤال
CaF₂ has Ksp = 3.2 × 10^-11 in pure water; what is its molar solubility?
الإجابة
2.0 × 10^-4 M. If the molar solubility is s, then [Ca²⁺] = s, [F⁻] = 2s, and Ksp = 4s³.
البطاقة ٣٢٦
السؤال
For N₂ + 3H₂ ⇌ 2NH₃, how is Qp written?
الإجابة
Qp = (P_NH₃)²/[(P_N₂)(P_H₂)³], using the current partial pressures rather than necessarily equilibrium values.
البطاقة ٣٢٧
السؤال
How does heating shift an endothermic forward reaction?
الإجابة
Toward products, and K increases because temperature changes the equilibrium constant.
البطاقة ٣٢٨
السؤال
Why do both forward and reverse rates change as equilibrium is approached?
الإجابة
As reactant and product concentrations change, the collision frequencies for the two directions change until their rates match.
البطاقة ٣٢٩
السؤال
CaF₂ has Ksp = 3.2 × 10^-11. What is its molar solubility in 0.10 M NaF?
الإجابة
About 3.2 × 10^-9 M. With [F⁻] ≈ 0.10 M, Ksp = [Ca²⁺][F⁻]² gives s = (3.2 × 10^-11)/(0.10)². The common ion lowers solubility but does not change Ksp at constant temperature.
البطاقة ٣٣٠
السؤال
What concentration data must be used to calculate Kc?
الإجابة
Equilibrium concentrations, each raised to its stoichiometric coefficient and excluding pure solids and liquids.
البطاقة ٣٣١
السؤال
What is a Brønsted–Lowry acid?
الإجابة
A proton donor.
البطاقة ٣٣٢
السؤال
How is pH defined?
الإجابة
pH = -log[H₃O⁺].
البطاقة ٣٣٣
السؤال
What is Ka for HA + H₂O ⇌ H₃O⁺ + A⁻?
الإجابة
Ka = [H₃O⁺][A⁻]/[HA].
البطاقة ٣٣٤
السؤال
How does stabilizing a base affect its basicity and the strength of its conjugate acid?
الإجابة
It makes the base weaker and its conjugate acid stronger. A more stable base is less willing to accept H⁺.
البطاقة ٣٣٥
السؤال
What is a Brønsted–Lowry base?
الإجابة
A proton acceptor.
البطاقة ٣٣٦
السؤال
At 25°C, what are Kw and the relationship between pH and pOH?
الإجابة
Kw = [H₃O⁺][OH⁻] = 1.0 × 10^-14. Taking negative logarithms gives pH + pOH = 14.00.
البطاقة ٣٣٧
السؤال
What is Kb for B + H₂O ⇌ BH⁺ + OH⁻?
الإجابة
Kb = [BH⁺][OH⁻]/[B].
البطاقة ٣٣٨
السؤال
Why can lowering pH increase the solubility of a salt containing a basic anion?
الإجابة
H₃O⁺ consumes the anion, pulling the dissolution equilibrium toward more dissolved ions.
البطاقة ٣٣٩
السؤال
What are conjugate acid–base pairs?
الإجابة
Species that differ by exactly one proton.
البطاقة ٣٤٠
السؤال
What is the pH of 1.0 × 10^-3 M HCl?
الإجابة
3.00, assuming complete dissociation and negligible water contribution.
البطاقة ٣٤١
السؤال
How are pKa and pKb defined?
الإجابة
pKa = -log Ka, and pKb = -log Kb.
البطاقة ٣٤٢
السؤال
Why does acid strength increase across a row of comparable hydrides?
الإجابة
Increasing electronegativity stabilizes the conjugate base and polarizes the H–A bond.
البطاقة ٣٤٣
السؤال
What is an amphiprotic species?
الإجابة
A species that can donate or accept a proton, such as HCO₃⁻.
البطاقة ٣٤٤
السؤال
What amounts remain after a limited amount of strong base partially neutralizes weak acid HA?
الإجابة
Subtract the reacted moles from HA and form the same number of moles of A⁻. The result gives the remaining HA and formed A⁻ amounts before any equilibrium or buffer-pH calculation.
البطاقة ٣٤٥
السؤال
How are Ka, Kb, pKa, and pKb related for a conjugate pair at 25°C?
الإجابة
KaKb = Kw = 1.0 × 10^-14, and pKa + pKb = pKw = 14.00.
البطاقة ٣٤٦
السؤال
When does pH have little effect on a salt's solubility?
الإجابة
When neither dissolved ion reacts appreciably with H₃O⁺ or OH⁻.
البطاقة ٣٤٧
السؤال
How does H₂O act in HCl + H₂O → H₃O⁺ + Cl⁻ and in NH₃ + H₂O ⇌ NH₄⁺ + OH⁻?
الإجابة
It acts as a base in the first reaction by accepting H⁺, and as an acid in the second by donating H⁺.
البطاقة ٣٤٨
السؤال
After mixing weak base B with strong acid, what controls the final solution in the three stoichiometric regimes?
الإجابة
Excess B leaves a B/BH⁺ buffer; equimolar amounts leave BH⁺, so the solution is acidic; excess strong acid sets the pH from the remaining H₃O⁺.
البطاقة ٣٤٩
السؤال
What two components make a typical weak-acid buffer?
الإجابة
A weak acid and a significant amount of its conjugate base.
البطاقة ٣٥٠
السؤال
What do the successive half-equivalence pH values approximate in a diprotic weak-acid titration?
الإجابة
The first approximates pKa₁ and the second approximates pKa₂ because each conjugate pair has equal concentrations at its half-equivalence point.
البطاقة ٣٥١
السؤال
Which acid is stronger, one with pKa 2 or pKa 5?
الإجابة
The acid with pKa 2; lower pKa means larger Ka.
البطاقة ٣٥٢
السؤال
What is the Henderson–Hasselbalch equation?
الإجابة
pH = pKa + log([A⁻]/[HA]).
البطاقة ٣٥٣
السؤال
Why are larger binary hydrides down a group often stronger acids?
الإجابة
The H–A bond becomes weaker as the central atom grows, so proton release is easier.
البطاقة ٣٥٤
السؤال
What mainly determines buffer capacity?
الإجابة
The concentrations of both members of the conjugate acid–base pair. Increasing both concentrations at a fixed ratio increases capacity without changing pH; capacity is best balanced for added acid and base when their concentrations are similar.
البطاقة ٣٥٥
السؤال
Why does acid increase CaCO₃ solubility?
الإجابة
H₃O⁺ converts CO₃²⁻ to HCO₃⁻ or carbonic acid species, reducing free carbonate and driving more CaCO₃ to dissolve.
البطاقة ٣٥٦
السؤال
What does pH < pKa imply for a weak-acid pair?
الإجابة
The protonated form HA predominates over A⁻.
البطاقة ٣٥٧
السؤال
What happens when stoichiometrically equal amounts of a monoprotic weak acid and strong base are mixed?
الإجابة
The weak acid is consumed to its conjugate base; at equivalence, the solution isn't a buffer containing both forms.
البطاقة ٣٥٨
السؤال
What is [H₃O⁺] when pH = 4.50?
الإجابة
3.2 × 10^-5 M, from [H₃O⁺] = 10^-pH.
البطاقة ٣٥٩
السؤال
What is the pH of 0.010 M Ba(OH)₂ at 25°C?
الإجابة
About 12.30. Complete dissociation gives [OH⁻] = 0.020 M, so pOH = 1.70. At 25°C, pH + pOH = 14.00, so pH = 12.30.
البطاقة ٣٦٠
السؤال
How does a buffer respond to a small amount of added strong acid?
الإجابة
Its conjugate base consumes H⁺, converting to the weak acid and limiting the pH change.
البطاقة ٣٦١
السؤال
Why is the equivalence-point solution basic in a monoprotic weak-acid–strong-base titration?
الإجابة
The conjugate base produced at equivalence reacts with water to form OH⁻, so the pH is above neutral—above 7.00 at 25°C.
البطاقة ٣٦٢
السؤال
How is percent ionization calculated for a weak acid or weak base?
الإجابة
For HA, use ([H₃O⁺]equilibrium ÷ [HA]initial) × 100%. For B, use ([BH⁺]equilibrium ÷ [B]initial) × 100%, under the usual monoprotic setup.
البطاقة ٣٦٣
السؤال
When is Henderson–Hasselbalch useful for an initial buffer-pH calculation?
الإجابة
Use it when both members of a conjugate acid–base pair are present in meaningful amounts, including after in-scope stoichiometry creates a buffer. Calculating the pH change after acid or base is added to an existing buffer is outside this deck’s scope.
البطاقة ٣٦٤
السؤال
Why does adding oxygen atoms usually strengthen oxyacids with the same central atom?
الإجابة
Extra oxygens withdraw electron density and delocalize negative charge in the conjugate base.
البطاقة ٣٦٥
السؤال
A prepared buffer is accidentally diluted to twice its intended volume; what happens to its pH and capacity?
الإجابة
Its pH stays nearly the same, and its capacity per liter is halved because both component concentrations halve. The total neutralizing moles in the sample remain unchanged.
البطاقة ٣٦٦
السؤال
How does adding OH⁻ affect Mg(OH)₂ solubility?
الإجابة
It decreases solubility through the common-ion effect, shifting Mg(OH)₂(s) ⇌ Mg²⁺ + 2OH⁻ toward the solid.
البطاقة ٣٦٧
السؤال
A buffer has equal [A⁻] and [HA]; what is its pH?
الإجابة
pH = pKa because log(1) = 0.
البطاقة ٣٦٨
السؤال
How should a weak acid–strong base mixture be solved before equivalence?
الإجابة
First use mole stoichiometry; if both HA and A⁻ remain, use the resulting buffer relation.
البطاقة ٣٦٩
السؤال
Why can pure neutral water have a pH other than 7.00?
الإجابة
Kw changes with temperature. Neutrality means [H₃O⁺] = [OH⁻], while pH = 7.00 only when Kw = 1.0 × 10^-14 at 25°C.
البطاقة ٣٧٠
السؤال
25.0 mL of 0.200 M HCl is diluted to 100.0 mL; what is the pH?
الإجابة
1.301. Dilution gives [H₃O⁺] = (0.200 M)(25.0 mL)/(100.0 mL) = 0.0500 M, so pH = -log(0.0500).
البطاقة ٣٧١
السؤال
How does a buffer respond to a small amount of added strong base?
الإجابة
The weak acid consumes OH⁻, forming conjugate base and water.
البطاقة ٣٧٢
السؤال
How do you find the final pH after mixing a strong acid and strong base at 25°C?
الإجابة
Use H₃O⁺ + OH⁻ → 2H₂O and compare their moles. Divide excess H₃O⁺ or OH⁻ by the total volume, then calculate pH or pOH from that excess concentration. Equal moles give pH 7.00 at 25°C.
البطاقة ٣٧٣
السؤال
What distinguishes acid strength from acid concentration?
الإجابة
Strength is the equilibrium tendency to donate H⁺, reflected by Ka or pKa; concentration is the amount of acid per solution volume.
البطاقة ٣٧٤
السؤال
If [A⁻]/[HA] = 10, how does pH compare with pKa?
الإجابة
pH = pKa + 1 because log 10 = 1.
البطاقة ٣٧٥
السؤال
Which conjugate base is more stable, one with localized or resonance-delocalized charge?
الإجابة
The resonance-delocalized conjugate base, which generally corresponds to the stronger acid.
البطاقة ٣٧٦
السؤال
Which 1.0 L buffer has greater capacity: 1.0 mol each of HA/A⁻ or 0.10 mol each at the same ratio?
الإجابة
The 1.0 mol pair; both have the same initial pH, but the larger amounts neutralize more added acid or base.
البطاقة ٣٧٧
السؤال
For BHX(s) ⇌ BH⁺ + X⁻, why can raising pH increase the salt's solubility?
الإجابة
OH⁻ consumes BH⁺ to form B and H₂O, so dissolution shifts right to replace BH⁺. This is a qualitative prediction, not a pH-dependent solubility calculation.
البطاقة ٣٧٨
السؤال
What does pH > pKa imply for a weak-acid pair?
الإجابة
The deprotonated form A⁻ predominates over HA.
البطاقة ٣٧٩
السؤال
For HA + B ⇌ A⁻ + BH⁺, which side is favored when pKa(HA) = 4 and pKa(BH⁺) = 9?
الإجابة
Products are favored. Proton transfer moves toward the weaker acid–base pair, and K ≈ 10^(9 − 4) = 10^5.
البطاقة ٣٨٠
السؤال
What is the pOH when [OH⁻] = 2.5 × 10^-4 M?
الإجابة
3.60, from -log(2.5 × 10^-4).
البطاقة ٣٨١
السؤال
What is the pH of 0.100 M HA when Ka = 1.0 × 10^-5?
الإجابة
About 3.00. The ICE setup gives Ka = x²/(0.100 − x); x ≈ 1.0 × 10^-3 M, and the 1.0% change validates the approximation.
البطاقة ٣٨٢
السؤال
Why does a buffer fail after too much strong acid is added?
الإجابة
Its conjugate base is depleted, so added H⁺ is no longer consumed effectively.
البطاقة ٣٨٣
السؤال
What do two clear equivalence regions on an acid titration curve suggest?
الإجابة
At least two distinguishable titratable protons; on a clean ideal curve with exactly two equivalence regions, this is consistent with a diprotic acid.
البطاقة ٣٨٤
السؤال
A buffer has pKa 4.8 and [A⁻]/[HA] = 0.10; what is pH?
الإجابة
3.8, from 4.8 + log(0.10).
البطاقة ٣٨٥
السؤال
Why is HCl stronger than HF in water despite F being more electronegative?
الإجابة
The H–F bond is much stronger; bond strength dominates this down-group binary-acid comparison.
البطاقة ٣٨٦
السؤال
Why does percent ionization increase when a weak acid is diluted?
الإجابة
Dilution shifts ionization toward more particles, so a larger fraction ionizes even though [H₃O⁺] decreases.
البطاقة ٣٨٧
السؤال
A buffer contains more HA than A⁻. Which addition can it neutralize in greater amount: strong acid or strong base?
الإجابة
Strong base. The larger HA reserve consumes more added OH⁻; a buffer with more A⁻ than HA instead has greater capacity for added strong acid.
البطاقة ٣٨٨
السؤال
Why can removing a basic anion increase a salt's molar solubility without changing Ksp?
الإجابة
The equilibrium shifts to replace the consumed ion; Ksp remains fixed at the same temperature.
البطاقة ٣٨٩
السؤال
Why can an acid–base indicator change color as pH changes?
الإجابة
Its protonated and deprotonated forms have different colors or other observable properties, and their relative amounts change with pH.
البطاقة ٣٩٠
السؤال
What buffer results from mixing 1.0 mol HA with 0.40 mol OH⁻?
الإجابة
0.60 mol HA and 0.40 mol A⁻ remain, forming a buffer before any equilibrium calculation.
البطاقة ٣٩١
السؤال
What is the pH of 0.200 M weak base B when Kb = 2.0 × 10^-5 at 25°C?
الإجابة
About 11.30. The ICE setup gives Kb = x²/(0.200 − x); x ≈ 2.0 × 10^-3 M OH⁻, and the 1.0% change validates the approximation.
البطاقة ٣٩٢
السؤال
Why does a weak acid alone not make an effective buffer?
الإجابة
It lacks a substantial conjugate-base reserve to consume added strong acid.
البطاقة ٣٩٣
السؤال
What controls pH after excess strong base passes equivalence?
الإجابة
The concentration of excess OH⁻ after accounting for reaction stoichiometry and total volume.
البطاقة ٣٩٤
السؤال
How should an indicator be chosen for a titration?
الإجابة
Its color-change range should fall within the steep pH change near the equivalence point.
البطاقة ٣٩٥
السؤال
How can a measured pH and known pKa give a conjugate-base/acid ratio?
الإجابة
Rearrange Henderson–Hasselbalch: [A⁻]/[HA] = 10^(pH − pKa).
البطاقة ٣٩٦
السؤال
Can a weak base and its conjugate acid form a buffer?
الإجابة
Yes, when both are present in significant amounts.
البطاقة ٣٩٧
السؤال
For equal-volume buffers with the same conjugate-base/acid ratio, how does adding the same amount of strong acid affect a more concentrated versus less concentrated buffer?
الإجابة
The concentrated buffer changes pH less because it has greater capacity.
البطاقة ٣٩٨
السؤال
How does equivalence-point pH compare for strong acid–strong base, weak acid–strong base, and weak base–strong acid titrations at 25°C?
الإجابة
Strong acid–strong base: pH 7.00. Weak acid–strong base: above 7.00 because the conjugate base reacts with water. Weak base–strong acid: below 7.00 because the conjugate acid reacts with water.
البطاقة ٣٩٩
السؤال
Why should mole ratios replace concentration ratios after mixing buffer solutions?
الإجابة
Both components share the same final volume, so that volume cancels in [A⁻]/[HA].
البطاقة ٤٠٠
السؤال
How does adding a little strong acid change a buffer's conjugate-base and conjugate-acid amounts?
الإجابة
The conjugate base decreases and its conjugate acid increases by the amount of strong acid consumed.
البطاقة ٤٠١
السؤال
What does entropy measure qualitatively?
الإجابة
The dispersal of matter and energy among available microstates.
البطاقة ٤٠٢
السؤال
How is standard reaction entropy calculated?
الإجابة
ΔS°rxn = ΣνS°(products) − ΣνS°(reactants).
البطاقة ٤٠٣
السؤال
What equation gives ΔG° from ΔH° and ΔS°, and what standard states do the degree symbols assume?
الإجابة
ΔG° = ΔH° − TΔS°. The standard states are pure substances, 1.0 M solutions, and gases at 1 atm or 1 bar; T is in kelvins and energy units must match.
البطاقة ٤٠٤
السؤال
Does thermodynamic favorability guarantee a fast reaction?
الإجابة
No. A favorable reaction can be slow when its activation barrier is large.
البطاقة ٤٠٥
السؤال
What is ΔG at equilibrium?
الإجابة
Zero under the current conditions because there is no net driving force.
البطاقة ٤٠٦
السؤال
Why can an endothermic dissolution still be thermodynamically favorable?
الإجابة
A sufficiently positive entropy change can make TΔS exceed positive ΔH, giving negative ΔG.
البطاقة ٤٠٧
السؤال
How can an unfavorable reaction be driven by a favorable one?
الإجابة
Couple them so their equations and ΔG values add to a negative overall ΔG.
البطاقة ٤٠٨
السؤال
Where does oxidation occur in every electrochemical cell?
الإجابة
At the anode.
البطاقة ٤٠٩
السؤال
How are standard cell potential and standard free energy related?
الإجابة
ΔG° = -nFE°cell.
البطاقة ٤١٠
السؤال
What equation gives cell potential under nonstandard conditions?
الإجابة
E = E° − (RT/nF) ln Q. When Q = 1, ln Q = 0, so E = E°.
البطاقة ٤١١
السؤال
How is electrical charge related to current and time?
الإجابة
q = It.
البطاقة ٤١٢
السؤال
Which phase has greater molar entropy, liquid water or ice at the same temperature?
الإجابة
Liquid water because its molecules have more accessible arrangements and motion.
البطاقة ٤١٣
السؤال
Do elements in their standard states have zero standard molar entropy?
الإجابة
No. Their ΔHf° is zero, but their absolute S° values are positive above 0 K.
البطاقة ٤١٤
السؤال
How do the four ΔH° and ΔS° sign combinations determine thermodynamic favorability across temperature?
الإجابة
ΔH° < 0 and ΔS° > 0 is favorable at every temperature; ΔH° > 0 and ΔS° < 0 is thermodynamically unfavored at every temperature. If both are positive, favorability requires high temperature; if both are negative, it requires low temperature.
البطاقة ٤١٥
السؤال
What does it indicate when a thermodynamically favored process does not occur at a measurable rate?
الإجابة
It is under kinetic control, commonly because of a high activation energy; no measurable reaction does not mean the system is at equilibrium.
البطاقة ٤١٦
السؤال
How are ΔG° and K related?
الإجابة
ΔG° = -RT ln K.
البطاقة ٤١٧
السؤال
What two contributions compete in dissolving an ionic solid?
الإجابة
Enthalpy changes from separating and solvating particles, and entropy changes from their new dispersal and solvent organization.
البطاقة ٤١٨
السؤال
What must cancel when coupled reactions are added?
الإجابة
Shared intermediates, leaving the desired net reaction.
البطاقة ٤١٩
السؤال
Where does reduction occur in every electrochemical cell?
الإجابة
At the cathode.
البطاقة ٤٢٠
السؤال
What sign of E°cell indicates a favorable standard galvanic reaction?
الإجابة
Positive E°cell, corresponding to negative ΔG°.
البطاقة ٤٢١
السؤال
If Q increases for a galvanic reaction, how does E change at fixed temperature?
الإجابة
E decreases according to the Nernst equation. Le Châtelier's principle does not apply to an operating cell away from equilibrium; use Q and Nernst reasoning instead.
البطاقة ٤٢٢
السؤال
How are moles of electrons found from charge?
الإجابة
Moles e⁻ = q/F, where F ≈ 96485 C mol^-1 e⁻.
البطاقة ٤٢٣
السؤال
How does producing more gas particles usually affect system entropy?
الإجابة
It increases entropy because the particles have more positional microstates.
البطاقة ٤٢٤
السؤال
Can a dissolution with negative ΔH be unfavorable?
الإجابة
Yes. A sufficiently negative entropy change at the stated temperature can make ΔG positive.
البطاقة ٤٢٥
السؤال
When can a process with ΔH > 0 and ΔS > 0 become favorable?
الإجابة
At sufficiently high temperature, when TΔS exceeds ΔH.
البطاقة ٤٢٦
السؤال
How does a catalyst affect ΔG?
الإجابة
It does not change ΔG; it lowers the activation barrier for both directions.
البطاقة ٤٢٧
السؤال
For A → B, ΔGf°(A) = -50 kJ mol^-1 and ΔGf°(B) = -80 kJ mol^-1. What is ΔG°rxn?
الإجابة
-30 kJ mol^-1. Use ΣνΔGf°(products) − ΣνΔGf°(reactants) = -80 − (-50).
البطاقة ٤٢٨
السؤال
Why can dissolving a gas in a liquid have a negative entropy change?
الإجابة
Gas particles lose much of their translational freedom when confined and solvated in the liquid.
البطاقة ٤٢٩
السؤال
If coupled steps have ΔG values +20 kJ and -35 kJ, what is overall ΔG?
الإجابة
-15 kJ, so the combined process is thermodynamically favorable under those conditions.
البطاقة ٤٣٠
السؤال
What role does each half-cell solution play in an electrochemical cell?
الإجابة
It supplies dissolved redox species at an electrode interface and carries ions within its compartment. Separate compartments prevent direct mixing while the external circuit and salt bridge connect the half-cells.
البطاقة ٤٣١
السؤال
How is E°cell found from standard reduction potentials?
الإجابة
E°cell = E°cathode − E°anode, using both tabulated values as reductions.
البطاقة ٤٣٢
السؤال
How does a cell's potential magnitude change as Q approaches or moves away from K, and what is E at equilibrium?
الإجابة
|E| falls toward zero as Q approaches K and grows as the system moves farther from equilibrium. At equilibrium, Q = K and E = 0.
البطاقة ٤٣٣
السؤال
How many moles of electrons pass when 1.93 × 10^5 C flows?
الإجابة
2.00 mol e⁻, from q/F.
البطاقة ٤٣٤
السؤال
How does a salt bridge maintain charge balance in a galvanic cell?
الإجابة
Anions migrate toward the anode compartment and cations toward the cathode compartment, countering the net charge imbalances created by the two half-reactions.
البطاقة ٤٣٥
السؤال
Why does raising a substance's temperature generally increase its entropy?
الإجابة
Energy spreads across more accessible particle energy states, increasing the number of possible microscopic arrangements.
البطاقة ٤٣٦
السؤال
When can a process with ΔH < 0 and ΔS < 0 be favorable?
الإجابة
At sufficiently low temperature, where the unfavorable -TΔS term is small.
البطاقة ٤٣٧
السؤال
Why can diamond persist even though graphite is more stable at standard conditions?
الإجابة
Conversion has a large activation barrier, so diamond is kinetically persistent.
البطاقة ٤٣٨
السؤال
What do the external circuit and measuring device do in an electrochemical cell?
الإجابة
The circuit carries electrons from anode to cathode; a voltmeter measures potential difference, while an ammeter in series measures current.
البطاقة ٤٣٩
السؤال
At constant temperature, how does increasing the volume available to a gas affect its entropy?
الإجابة
Entropy increases because the gas particles can occupy more positions in the larger space, so more microstates are accessible.
البطاقة ٤٤٠
السؤال
How does reversing one coupled reaction affect its ΔG?
الإجابة
It reverses the sign of that reaction's ΔG.
البطاقة ٤٤١
السؤال
Why is n required in ΔG° = -nFE°?
الإجابة
It is the moles of electrons transferred per balanced reaction, linking charge flow to reaction extent.
البطاقة ٤٤٢
السؤال
What makes an electrolytic cell operate?
الإجابة
An external power source drives a thermodynamically unfavorable redox reaction; oxidation still occurs at the anode and reduction at the cathode.
البطاقة ٤٤٣
السؤال
In an Mⁿ⁺/M concentration cell, which half-cell is the anode: the dilute or concentrated ion solution?
الإجابة
The dilute half-cell. Oxidation produces Mⁿ⁺ there, while reduction consumes Mⁿ⁺ in the concentrated half-cell, so electrons flow from dilute to concentrated as the concentrations move toward equality.
البطاقة ٤٤٤
السؤال
How is deposited metal mass found from current and time?
الإجابة
Find q = It, convert q/F to moles e⁻, use the half-reaction ratio to moles metal, then multiply by molar mass.
البطاقة ٤٤٥
السؤال
Given product S° total 500 J mol^-1 K^-1 and reactant total 420 J mol^-1 K^-1, what is ΔS°?
الإجابة
+80 J mol^-1 K^-1.
البطاقة ٤٤٦
السؤال
How do electrode masses change in a Zn–Cu galvanic cell?
الإجابة
The Zn anode loses mass as Zn → Zn²⁺ + 2e⁻, while the Cu cathode gains mass as Cu²⁺ + 2e⁻ → Cu.
البطاقة ٤٤٧
السؤال
What is ΔG° when ΔH° = 50 kJ mol^-1, ΔS° = 0.200 kJ mol^-1 K^-1, and T = 300 K?
الإجابة
-10 kJ mol^-1, from ΔG° = 50 − (300)(0.200).
البطاقة ٤٤٨
السؤال
Why can temperature change a solid's solubility?
الإجابة
Temperature changes the balance of ΔH and TΔS, so it changes the free energy of dissolution and the equilibrium constant.
البطاقة ٤٤٩
السؤال
What does the size of ΔG° relative to RT imply about K?
الإجابة
ΔG° near zero gives K near 1. When |ΔG°| is much larger than RT, K is far from 1: negative ΔG° gives K ≫ 1, while positive ΔG° gives K ≪ 1.
البطاقة ٤٥٠
السؤال
Bubbles form at an inert cathode in acidic solution; which half-reaction can explain them?
الإجابة
2H⁺ + 2e⁻ → H₂(g). Gas evolution at the cathode can be direct evidence of reduction.

Translucent laboratory glassware, particle clusters, and flowing blue-to-amber energy curves on a dark background.

٤٥٠ بطاقة