AP Chemistry

Browse readings and complete checks by topic.

• Moles and Molar MassReading · Chemical quantities and reaction language

  Name the counted entity and connect grams, moles and particle numbers.

• Elemental Composition of Pure SubstancesReading · Chemical quantities and reaction language

  Use fixed elemental composition to find mass fractions and empirical formulas.

• Composition of MixturesReading · Chemical quantities and reaction language

  Distinguish pure-substance composition from a mixture and justify a mass-balance model.

• Solutions and MixturesReading · Chemical quantities and reaction language

  Prepare for reactions in solution: use final solution volume, molarity, dissociation and dilution.

• Introduction for ReactionsReading · Chemical quantities and reaction language

  Separate observations from evidence that a new chemical species has formed.

• Net Ionic EquationsReading · Chemical quantities and reaction language

  Write molecular, complete ionic and net ionic equations; check atoms, charge and states.

• Representations of ReactionsReading · Chemical quantities and reaction language

  Construct before-and-after reaction particle models with a consistent key and complete inventory.

• Physical and Chemical ChangesReading · Chemical quantities and reaction language

  Explain physical and chemical changes through the interactions and species that change.

• StoichiometryReading · Chemical quantities and reaction language

  Use reacting proportions to find the limiting reactant, product and remaining excess.

• Types of Chemical ReactionsReading · Chemical quantities and reaction language

  Classify proton transfer, oxidation-number change and precipitation using chemical evidence.

• The MoleSupporting reading · Chemical quantities and reaction language

  Alternative mole and dimensional-analysis explanation; use the native lesson and complete checks for the teaching sequence.

• Chemical EquationsSupporting reading · Chemical quantities and reaction language

  Alternative worked examples of balancing equations without changing substance formulas.

• StoichiometrySupporting reading · Chemical quantities and reaction language

  Alternative stoichiometric conversion examples after the mole and equation lessons.

• Limiting ReactantsSupporting reading · Chemical quantities and reaction language

  Alternative limiting-reactant and excess-ion examples with the accepted source revisions.

• Mass Spectra of ElementsReading · Atoms, electrons, and periodic patterns

  Read isotope mass and relative abundance separately, normalize intensities and calculate a weighted mass.

• Atomic Structure and Electron ConfigurationReading · Atoms, electrons, and periodic patterns

  Build electron configurations and explain electron removal through distance, shielding and attraction.

• Photoelectron SpectroscopyReading · Atoms, electrons, and periodic patterns

  Use ideal photoelectron peak populations and binding energies as evidence for occupied subshells.

• Periodic TrendsReading · Atoms, electrons, and periodic patterns

  Explain periodic comparisons with charge, distance, shielding and supplied exception data.

• Valence Electrons and Ionic CompoundsReading · Atoms, electrons, and periodic patterns

  Connect repeating valence patterns to familiar ion charges and electrically neutral compound formulas.

• Advanced Electron ConfigurationsFurther study · Atoms, electrons, and periodic patterns

  Further study in orbital-box notation and magnetic behavior; exception-configuration memorization remains outside the required AP targets.

• Types of Chemical BondsReading · Bonds and molecular shape

  Compare sharing, ionic character and delocalized metallic electrons using properties as evidence.

• Intramolecular Force and Potential EnergyReading · Bonds and molecular shape

  Read the bond-energy minimum: separate equilibrium distance, dissociation energy and interaction force.

• Structure of Ionic SolidsReading · Bonds and molecular shape

  Represent an extended ionic solid with the correct ratio, charge balance and mobile-charge explanation.

• Structure of Metals and AlloysReading · Bonds and molecular shape

  Explain metallic conduction and alloy deformation using delocalized electrons and guest-atom positions.

• Lewis DiagramsReading · Bonds and molecular shape

  Construct Lewis diagrams from an electron budget; check connectivity, local duets/octets and net charge.

• Resonance and Formal ChargeReading · Bonds and molecular shape

  Use formal-charge sums and equivalent resonance contributors without implying alternating molecules.

• VSEPR and HybridizationReading · Bonds and molecular shape

  Count domains, distinguish electron and atom geometry, and add bond-dipole vectors.

• Molecular Structure of Acids and BasesReading · Acids, bases, and pH

  Identify structural proton sites and explain strength through the resulting conjugate species.

• Molecular Orbital TheoryFurther study · Bonds and molecular shape

  Further study: an original comparison of bonding models; molecular-orbital theory does not become a required geometry lesson.

• What is Organic?Further study · Bonds and molecular shape

  Further study: browse the original introduction to organic classes and functional groups.

• Basic Organic NomenclatureFurther study · Bonds and molecular shape

  Further study: original hydrocarbon nomenclature and skeletal representations.

• Advanced NomenclatureFurther study · Bonds and molecular shape

  Further study: original side-chain, functional-group and linkage nomenclature.

• Chemical Properties of OrganicsFurther study · Bonds and molecular shape

  Further study: original organic-property examples; use the native intermolecular-force and solubility lessons for the reviewed main path.

• Intermolecular and Interparticle ForcesReading · States of matter and gases

  Draw the available interactions for a pair of particles, including mixed-pair hydrogen bonding and dispersion.

• Properties of SolidsReading · States of matter and gases

  Link solid structure, particle mobility and disrupted contacts to observed material properties.

• Solids, Liquids, and GasesReading · States of matter and gases

  Represent motion, spacing and intact particle identity in solids, liquids and gases.

• Ideal Gas LawReading · States of matter and gases

  Use the ideal gas law and partial pressures with fixed-variable labels and compatible units.

• Kinetic Molecular TheoryReading · States of matter and gases

  Distinguish speed and energy distributions and relate wall momentum transfer to gas pressure.

• Deviation from Ideal Gas LawReading · States of matter and gases

  Use matched conditions to distinguish attraction and excluded-volume effects from ideal behavior.

• Energy of Phase ChangesReading · Energy transfer and enthalpy

  Account separately for warming/cooling and fixed-pressure phase-transition energy.

• Introduction to EntropyReading · Entropy, free energy, and chemical change

  Explain entropy changes through accessible arrangements, phase, space and energy without relying on visual disorder.

• Representations of SolutionsReading · Solutions and solubility

  Construct charge-balanced solution windows with a stated icon scale, represented volume and hydration orientation.

• SolubilityReading · Solutions and solubility

  Explain relative solubility through interactions lost and formed, while separating heat release from favorability.

• Separation of Solutions and MixturesReading · Chemical measurement and laboratory evidence

  Choose filtration, chromatography or distillation from the physical difference available; interpret results under matched conditions.

• Introduction to Solubility EquilibriaReading · Chemical equilibrium

  Build dissolution expressions, distinguish ion concentration from salt solubility, and use post-mixing Qsp.

• Common-Ion EffectReading · Chemical equilibrium

  Include every common-ion source and verify any negligible-change approximation.

• pH and SolubilityReading · Acids, bases, and pH

  Couple dissolution and proton-transfer equations, distinguishing free ions in Ksp from total dissolved material.

• Free Energy of DissolutionReading · Entropy, free energy, and chemical change

  Account for lattice, solvent and hydration contributions and the sensitivity of a small net dissolution result.

• SolvationSupporting reading · Solutions and solubility

  Alternative original solvation reading with accepted viewing revisions; extended solubility-rule memorization is not added to the main path.

• Spectroscopy and the Electromagnetic SpectrumReading · Chemical measurement and laboratory evidence

  Connect spectral regions to rotational, vibrational or electronic transitions without confusing excitation with electron ejection.

• Properties of PhotonsReading · Chemical measurement and laboratory evidence

  Convert wavelength to frequency and photon energy; distinguish photon energy from light intensity.

• Beer-Lambert LawReading · Chemical measurement and laboratory evidence

  Build and use an absorbance calibration with a justified intercept, range, blank and error direction.

• Introduction to TitrationReading · Chemical measurement and laboratory evidence

  Use reacting amounts to distinguish titration equivalence from the observed endpoint and interpret a buret reading.

• Heat Capacity and CalorimetryReading · Energy transfer and enthalpy

  Read a thermometer and build a heat balance including solution, cup and any external recipients.

• Acid-Base TitrationsReading · Buffers and titrations

  Interpret weak/strong and resolved polyprotic titration regions through stoichiometry, major species and half-step pKa.

• Basic Procedures for Lab-workSupporting reading · Chemical measurement and laboratory evidence

  Use the accepted source revisions for preparation, final-volume and measurement reasoning under the instructor’s laboratory procedures.

• Endothermic and Exothermic ProcessesReading · Energy transfer and enthalpy

  Choose the system boundary and explain heat-transfer signs without equating temperature with stored energy.

• Energy DiagramsReading · Energy transfer and enthalpy

  Draw initial/final energy levels and a correctly signed change; a level diagram alone gives no reaction time.

• Heat Transfer and Thermal EquilibriumReading · Energy transfer and enthalpy

  Explain thermal contact and a heat-capacity-weighted final temperature through energy conservation.

• Introduction to Enthalpy of ReactionReading · Energy transfer and enthalpy

  Scale reaction heat with the balanced equation and distinguish reaction energy from the surroundings’ warming.

• Bond EnthalpiesReading · Energy transfer and enthalpy

  Count broken and formed bonds and state the gas-phase average-bond-enthalpy approximation.

• Enthalpy of FormationReading · Energy transfer and enthalpy

  Use coefficient-weighted formation values with the correct phase and reference-state convention.

• Hess’s LawReading · Energy transfer and enthalpy

  Construct a Hess accounting path by reversal, scaling and cancellation with energy conservation.

• Laws of ThermodynamicsFurther study · Energy transfer and enthalpy

  Further study: the original single-section thermodynamics overview, with accepted revisions; its heading does not establish comprehensive thermodynamics coverage.

• Reaction RatesReading · Reaction rates and mechanisms

  Name the species and distinguish its disappearance rate from a stoichiometrically normalized reaction rate.

• Introduction to Rate LawReading · Reaction rates and mechanisms

  Infer empirical orders from controlled initial-rate comparisons and check rate-constant units.

• Concentration Changes Over TimeReading · Reaction rates and mechanisms

  Choose concentration, logarithmic or reciprocal graphs and interpret model limits and half-life.

• Elementary ReactionsReading · Reaction rates and mechanisms

  Infer a step’s rate law from molecularity only when the event is explicitly elementary.

• Collision ModelReading · Reaction rates and mechanisms

  Explain energy-tail area and encounter orientation with normalized collision models.

• Reaction Energy ProfileReading · Reaction rates and mechanisms

  Read forward and reverse barriers separately from endpoint energy change; the coordinate is not time.

• Introduction to Reaction MechanismsReading · Reaction rates and mechanisms

  Sum a balanced mechanism and distinguish intermediate, catalyst and transition state.

• Reaction Mechanism and Rate LawReading · Reaction rates and mechanisms

  Test slow-first-step predictions against observed rate laws under stated supply conditions.

• Pre-Equilibrium ApproximationReading · Reaction rates and mechanisms

  Use rapid forward/reverse rate balance to eliminate an intermediate before predicting a net rate law.

• Multistep Reaction Energy ProfileReading · Reaction rates and mechanisms

  Measure each local multistep barrier from its starting valley rather than an arbitrary zero.

• CatalysisReading · Reaction rates and mechanisms

  Explain complete regenerated catalytic cycles and why a changed path leaves the endpoint enthalpy unchanged.

• Thermodynamic and Kinetic ControlReading · Entropy, free energy, and chemical change

  Draw separate endpoint and barrier differences to explain a favorable but slow or kinetically trapped change.

• Introduction to EquilibriumReading · Chemical equilibrium

  Distinguish constant unequal concentrations from equal nonzero forward and reverse rates.

• Direction of Reversible ReactionsReading · Chemical equilibrium

  Use simultaneous forward/reverse events and stoichiometry to explain net direction.

• Reaction Quotient and Equilibrium ConstantReading · Chemical equilibrium

  Write Q and K for the stated species and phases; pure solids are conditions, not variable terms.

• Calculating the Equilibrium ConstantReading · Chemical equilibrium

  Infer K from equilibrium measurements after converting amounts to concentrations or partial pressures.

• Magnitude of the Equilibrium ConstantReading · Chemical equilibrium

  Interpret K for the exact equation without treating it as a speed or unqualified percentage.

• Properties of the Equilibrium ConstantReading · Chemical equilibrium

  Reverse, scale and add equations while transforming their quotients and equilibrium constants consistently.

• Calculating Equilibrium ConcentrationsReading · Chemical equilibrium

  Choose net progress from Q/K and solve checked equilibrium concentration changes.

• Representations of EquilibriumReading · Chemical equilibrium

  Construct a scaled equilibrium particle representation with atom conservation and ongoing opposite events.

• Introduction to Le Châtelier’s PrincipleReading · Chemical equilibrium

  Separate the immediate physical disturbance from the subsequent net reaction and measurement response.

• Reaction Quotient and Le Châtelier’s PrincipleReading · Chemical equilibrium

  Use quotient algebra to justify a disturbance’s direction; temperature can also change K.

• Free Energy and EquilibriumReading · Entropy, free energy, and chemical change

  Connect standard free energy to K and distinguish it from zero actual driving force at Q = K.

• Introduction to Acid-Base ReactionsReading · Acids, bases, and pH

  Identify the actual proton donor and acceptor and follow charge through conjugate pairs.

• Introduction to Acids and BasesReading · Acids, bases, and pH

  Use pH, pOH and the temperature-dependent water equilibrium without treating either ion as absent.

• pH and pOH of Strong Acids and BasesReading · Acids, bases, and pH

  Determine strong-acid/base ion populations after dilution under a justified concentration model.

• Weak Acid and Base EquilibriaReading · Acids, bases, and pH

  Solve weak-acid and weak-base equilibria, check depletion and connect conjugate constants.

• pH and pKaReading · Acids, bases, and pH

  Use pH minus pKa to explain dominant protonation forms; revisit indicator selection with titration curves.

• Acid-Base Reactions and BuffersReading · Buffers and titrations

  React amounts first, identify major remaining species, and then select an equilibrium or excess-ion model.

• Properties of BuffersReading · Buffers and titrations

  Explain how both weak conjugate forms consume small additions and why buffering has finite limits.

• Henderson-Hasselbalch EquationReading · Buffers and titrations

  Calculate the current pH of an established buffer from a justified base/acid ratio.

• Buffer CapacityReading · Buffers and titrations

  Separate ratio-controlled pH from total and directional capacity; compare controlled equal-volume samples.

• Absolute Entropy and Entropy ChangeReading · Entropy, free energy, and chemical change

  Use absolute molar entropy values and phase-specific coefficient sums rather than formation-enthalpy zero rules.

• Gibbs Free Energy and Thermodynamic FavorabilityReading · Entropy, free energy, and chemical change

  Combine enthalpy and entropy, compare temperature sign cases and distinguish standard references from actual composition.

• Coupled ReactionsReading · Entropy, free energy, and chemical change

  Add a connected coupled pathway or identify the external energy source that drives an unfavorable process.

• Cell Potential and Free EnergyReading · Redox and electrochemistry

  Use balanced electron count and reduction potentials to relate cell direction to standard free energy.

• Oxidation-Reduction (Redox) ReactionsReading · Redox and electrochemistry

  Balance complete redox half-reactions in the stated acidic or basic medium and cancel electrons.

• Galvanic (Voltaic) and Electrolytic CellsReading · Redox and electrochemistry

  Construct a labeled cell with separate electron and ion paths, electrode reactions and correct meter roles.

• Cell Potential Under Nonstandard ConditionsReading · Redox and electrochemistry

  Explain composition-dependent potential and concentration cells without calling an operating cell an equilibrium state.

• Electrolysis and Faraday’s LawReading · Redox and electrochemistry

  Convert charge and current-time data through electron stoichiometry to chemical amount, with efficiency assumptions.

• Introduction to Oxidation-ReductionSupporting reading · Redox and electrochemistry

  Alternative original oxidation-number and electron-accounting explanation with accepted revisions; keep source enrichment terms in their existing scope.

• The Galvanic CellSupporting reading · Redox and electrochemistry

  Alternative original cell, half-reaction and potential explanation with accepted revisions; use native tasks for the complete learner-created cell check.

• ElectrolysisSupporting reading · Redox and electrochemistry

  Apply charge accounting to the original stipulated electrolysis gas models with accepted revisions; keep water/solute competition and gas conditions explicit.

• BatteriesFurther study · Redox and electrochemistry

  Further study: original battery types and explicitly specified circuit enrichment; a battery label alone does not determine current.

• CorrosionFurther study · Redox and electrochemistry

  Further study: original capacity and cathodic-protection models with accepted revisions; ideal charge capacity is not an engineering lifetime guarantee.

• Connect a formula-unit count to massCheck understanding · Chemical quantities and reaction language

  Find sample mass and oxygen-atom count, then explain the correspondence between particle mass and molar mass.

  Separate worked reasoning and criteria →
• Construct a reaction particle modelCheck understanding · Chemical quantities and reaction language

  Create both molecular panels or equivalent coordinate layouts, retain the excess reactant, and verify both atom inventories.

  An actual learner-created representation is required; a final count or reading-completion tick alone does not demonstrate this action.

  Separate worked reasoning and criteria →
• Find the limiting reactant and test a changed supplyCheck understanding · Chemical quantities and reaction language

  Compare the product each reactant can support, find excess remaining, and explain when doubling one supply stops doubling product.

  Separate worked reasoning and criteria →
• Evaluate a configuration against PES evidenceCheck understanding · Atoms, electrons, and periodic patterns

  Reject an impossible subshell occupancy and identify the neutral atom from the corrected peak populations.

  Separate worked reasoning and criteria →
• Explain a periodic pattern from ionization dataCheck understanding · Atoms, electrons, and periodic patterns

  Use the position of the large energy jump to infer valence count, then justify a radius comparison through effective attraction.

  Separate worked reasoning and criteria →
• Construct and justify a Lewis diagramCheck understanding · Bonds and molecular shape

  Build HCN with a counted electron budget, correct bond orders and a hydrogen-duet explanation.

  Separate worked reasoning and criteria →
• Connect a created structure to shape and polarityCheck understanding · Bonds and molecular shape

  Draw NH3 with its lone pair, then compare domain count, geometry, angles and dipole-vector cancellation for three species.

  Separate worked reasoning and criteria →
• Choose a graph that reveals the gas relationshipCheck understanding · States of matter and gases

  Linearize pressure-volume data with correct slope units and remove the supplied water-vapor pressure.

  Separate worked reasoning and criteria →
• Construct kinetic particle sketchesCheck understanding · States of matter and gases

  Create equal-volume intact-molecule layouts with varied speed arrows, compare typical speeds, and justify equal ideal pressures at equal n, V and T.

  The task requires constructed sketches or coordinate layouts. It is an ideal model with equal amounts and temperature, not measured molecular trajectories.

  Separate worked reasoning and criteria →
• Use evidence to distinguish softening from bond cleavageCheck understanding · States of matter and gases

  Explain a polymer flexibility change and name evidence that could distinguish changed contacts from a changed covalent backbone.

  Separate worked reasoning and criteria →
• Construct and compare two solution particle windowsCheck understanding · Solutions and solubility

  Create both labeled ion-and-water sketches, distinguish covalent bonds from hydration contacts, and compare count per represented volume.

  Construction includes the volume and icon-amount legend; more icons alone do not establish greater concentration.

  Separate worked reasoning and criteria →
• Explain a dilution and preparation errorCheck understanding · Solutions and solubility

  Conserve solute amount, calculate the final concentration and trace an overfilled flask to a low concentration.

  Separate worked reasoning and criteria →
• Predict precipitation from the mixed solutionCheck understanding · Solutions and solubility

  After the equilibrium chapter, use post-mixing concentrations for Qsp, explain the stock-concentration error and interpret a separate saturated measurement.

  Use after Q/K and dissolution stoichiometry. The stated dilute single-solid model supplies the required solubility assumptions.

  Separate worked reasoning and criteria →
• Judge a chromatography identity claimCheck understanding · Chemical measurement and laboratory evidence

  Specify a controlled same-system comparison and explain why even matching migration is supporting evidence rather than unique identification.

  A supplied-data/method-reasoning task; it does not establish completion of a laboratory investigation.

  Separate worked reasoning and criteria →
• Choose a defensible absorbance measurementCheck understanding · Chemical measurement and laboratory evidence

  Dilute an unknown into the validated range, preserve wavelength/path/blank controls, and justify investigating a contradictory standard.

  The supplied calibration task and an interactive model are preparation for laboratory reasoning, not evidence that the student completed a laboratory investigation.

  Separate worked reasoning and criteria →
• Distinguish titration precision from accuracyCheck understanding · Chemical measurement and laboratory evidence

  Trace consistent endpoint overshoot through recorded titrant moles to an overestimated analyte concentration.

  Separate worked reasoning and criteria →
• Read instruments and account for both heat recipientsCheck understanding · Energy transfer and enthalpy

  Estimate thermometer readings, calculate solution and cup heat, infer dissolution enthalpy, and justify precision and uncertainty.

  Supplied instrument scales and data; no experiment is performed by completing this task.

  Separate worked reasoning and criteria →
• Build and justify a Hess pathCheck understanding · Energy transfer and enthalpy

  Reverse and scale complete equations, show cancellation including phases, and connect the summed heat to energy conservation.

  Separate worked reasoning and criteria →
• Infer and test a rate lawCheck understanding · Reaction rates and mechanisms

  Use controlled trial ratios, determine k with units and make an independent rate prediction.

  Separate worked reasoning and criteria →
• Test whether rate orders identify a unique mechanismCheck understanding · Reaction rates and mechanisms

  Derive two matching predicted laws and explain what additional supplied evidence would distinguish the mechanisms.

  Separate worked reasoning and criteria →
• Explain two complete catalytic routesCheck understanding · Reaction rates and mechanisms

  Identify protonated and surface-bound intermediates, show catalyst restoration and justify the unchanged net enthalpy.

  Separate worked reasoning and criteria →
• Calculate and check an equilibrium compositionCheck understanding · Chemical equilibrium

  Use initial Q to choose direction, solve balanced changes and verify nonnegative values, total amount and Q = K.

  Separate worked reasoning and criteria →
• Construct a later equilibrium snapshotCheck understanding · Chemical equilibrium

  Create a same-scale particle model with forward/reverse event arrows and explain average composition and small-picture limits.

  Separate worked reasoning and criteria →
• Compare dissolution with a common-ion controlCheck understanding · Chemical equilibrium

  Include the added ion source, check the approximation and predict a changed concentration without changing fixed-temperature Ksp.

  Separate worked reasoning and criteria →
• Solve a weak-base equilibrium and explain its particlesCheck understanding · Acids, bases, and pH

  Find the produced hydroxide, test the approximation and describe major species and conjugate acidity.

  Separate worked reasoning and criteria →
• Connect acid/base strength to structures and proton sitesCheck understanding · Acids, bases, and pH

  Draw or describe conjugate species, explain resonance and induction, and distinguish hydroxide dissociation from unlimited solubility.

  Separate worked reasoning and criteria →
• Explain pH-dependent solubility in both directionsCheck understanding · Acids, bases, and pH

  Write linked proton-transfer and dissolution equations, trace the free-ion quotient and distinguish free from total dissolved material.

  Qualitative supplied single-solid models only. Numerical solubility-versus-pH calculations and competing-phase generalizations are outside this task’s scope.

  Separate worked reasoning and criteria →
• Interpret a weak-acid titration and compare equivalence speciesCheck understanding · Buffers and titrations

  Find initial concentration and pKa, identify major species, explain basic weak-acid equivalence and a delivery-tip bubble bias; then compare weak-base and strong/strong equivalence.

  Complete supplied titration data and assumptions are in the prompt. The accompanying model supports interpretation; it does not establish a completed laboratory investigation.

  Separate worked reasoning and criteria →
• Explain how a buffer responds to added acid and baseCheck understanding · Buffers and titrations

  Choose an effective weak conjugate pair, write both proton-transfer reactions and explain a finite rather than perfectly fixed pH response.

  The response is qualitative; this does not add an excluded numerical buffer pH-change calculation.

  Separate worked reasoning and criteria →
• Compare buffer capacity at equal starting pHCheck understanding · Buffers and titrations

  Separate pair ratio from reservoir amounts, identify directional capacity and trace accidental dilution through a controlled comparison.

  Capacity reasoning uses supplied component amounts; the fixed-concentration interactive model does not establish capacity scaling.

  Separate worked reasoning and criteria →
• Explain temperature, reference states and the sign casesCheck understanding · Entropy, free energy, and chemical change

  Calculate free-energy changes and boundaries with matching units; distinguish standard-state references, actual composition, stable phases and reaction speed.

  Separate worked reasoning and criteria →
• Build a dissolution energy and entropy ledgerCheck understanding · Entropy, free energy, and chemical change

  Assign and sum lattice, solvent and hydration contributions, then test how uncertainty can reverse the small net free-energy prediction.

  A hypothetical standard-state bookkeeping path is not a measured solubility or a claim about every salt.

  Separate worked reasoning and criteria →
• Explain what physically couples two changesCheck understanding · Entropy, free energy, and chemical change

  Cancel the shared intermediate, add free energies and identify the mechanism or external energy source; disconnected vessels do not establish coupling.

  Separate worked reasoning and criteria →
• Construct and explain a complete operating cellCheck understanding · Redox and electrochemistry

  Draw half-reactions, electron and bridge-ion paths, mass changes and both meter connections; explain bridge removal and voltage versus sustained current.

  A learner-created representation is required. A voltage model or a correct label alone does not replace the complete cell diagram or establish laboratory completion.

  Separate worked reasoning and criteria →
• Keep the sign of a written cell directionCheck understanding · Redox and electrochemistry

  Calculate the assigned-direction potential and free energy, explain the favored reverse and the external energy needed for the original direction.

  Separate worked reasoning and criteria →
• Convert deposition through electron chargeCheck understanding · Redox and electrochemistry

  Use the stated half-reactions to connect metal moles, charge and time, and explain why equal charge cannot establish equal mass without molar masses.

  The stipulated constant-current, 100%-efficiency model is explicit. The interactive voltage model does not calculate plating mass or charge.

  Separate worked reasoning and criteria →