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AQA AS-Level Chemistry 7405
Atomic Structure
Topic overviewFundamental ParticlesMass Number and IsotopesTime of Flight Mass Spectrometry: Ionisation and AccelerationTime of Flight Mass Spectrometry: Drift, Detection and Calculating m/zElectron Configuration: Sub-shells and OrbitalsElectron Configuration: Writing Configurations for Atoms and IonsIonisation Energies and Periodic Trends
Amount of Substance
Topic overviewRelative Atomic and Molecular MassThe Mole and the Avogadro ConstantThe Ideal Gas EquationEmpirical and Molecular FormulaBalanced Equations and Reaction CalculationsAtom Economy and Percentage YieldAcid-Base Titrations: Principles, Indicators and ApparatusAcid-Base Titrations: Standard Solutions and Calculations
Bonding
Topic overviewIonic BondingCovalent, Dative Covalent and Metallic BondingCrystal Structures: Giant Ionic Lattices and DiamondCrystal Structures: Graphite and Simple Molecular SolidsShapes of Molecules and Ions: VSEPR and Electron Pair RepulsionShapes of Molecules and Ions: Predicting Shapes and Bond AnglesElectronegativity and Bond PolarityIntermolecular Forces
Energetics and Thermodynamics
Kinetics
Chemical Equilibria
Redox and Electrochemistry
Periodicity and Group Chemistry
Topic overviews, p, d and f Block ClassificationTrends in Period 3Group 2 Trends in Atomic Radius, Ionisation Energy and Melting PointReactions of Group 2 with WaterSolubility Trends of Group 2 HydroxidesSolubility Trends of Group 2 SulfatesUses of Group 2 CompoundsTest for Sulfate IonsTrends in Electronegativity and Boiling Point of HalogensHalogens as Oxidising Agents and Displacement ReactionsHalide Ions as Reducing Agents: Chloride and BromideHalide Ions as Reducing Agents: Iodide, and the EquationsTest for Halide Ions Using Silver NitrateTests for Ammonium, Group 2, Hydroxide and Carbonate IonsReactions of Chlorine with WaterReactions of Chlorine with Cold Dilute NaOH and Water Treatment
Introduction to Organic Chemistry
Hydrocarbons
Topic overviewAlkanes, Fractional Distillation and CrackingCombustion of Alkanes and PollutantsFree Radical Chlorination of AlkanesAlkenes: Structure, Bonding and Electrophilic AdditionMarkovnikov's Rule and Carbocation StabilityAddition Polymers and Repeating UnitsProperties and Uses of Polyalkenes
Halogenoalkanes, Alcohols and Organic Analysis
Topic overviewNucleophilic Substitution of HalogenoalkanesEffect of Bond Enthalpy on Reaction RateElimination Reactions and Competing MechanismsCFCs and Ozone DepletionIndustrial Production of AlcoholsBiofuels and Carbon NeutralityClassification and Oxidation of AlcoholsDistinguishing Aldehydes and KetonesElimination of Water from AlcoholsTest-Tube Reactions for Functional GroupsMass Spectrometry and Molecular FormulaInfrared Spectroscopy, Functional Groups and Global Warming
Energetics and Thermodynamics
- 4 subtopics
- 24 things to know
- Papers 1 and 3
What Energetics and Thermodynamics covers
Energetics and thermodynamics is examined on Papers 1, 2 and 3, with thermodynamics on Paper 1 only. It starts with measuring enthalpy change by calorimetry and Hess's law, then builds to Born-Haber cycles, entropy, and the free energy calculation that decides whether a reaction happens at all.
Where it is assessed
Papers 1 and 3
Inorganic and physical chemistry, then the synoptic paper.
Check the AQA specification ↗The 4 subtopics
Each one has its own page. AQA AS Chemistry students sit this topic in the first year.
- Enthalpy Change and Standard ConditionsExothermic and endothermic changes, standard conditions, and the standard enthalpy definitions.Open →
- Calorimetry and Heat Change CalculationsUsing q = mcΔT, converting to enthalpy change per mole, and the sources of error.Open →
- Hess's Law and Enthalpy CyclesHess's law, and building cycles from enthalpies of formation or combustion.Open →
- Mean Bond EnthalpiesWhy bond enthalpies are averages, and estimating enthalpy change from bonds broken and made.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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What does the Gibbs free energy equation tell you about feasibility?
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What is enthalpy change (ΔH)?
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Besides pressure, what else must be stated for standard conditions?
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What equation is used to calculate the heat change in a reaction?
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In the equation q = mcΔT, what does q represent?
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State Hess's law.
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What does Hess's law allow us to calculate?
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What is the definition of mean bond enthalpy?
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What physical state must reactants and products be in when using mean bond enthalpies to calculate enthalpy changes?
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What is lattice enthalpy of dissociation?
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What three enthalpy terms are related in the enthalpy cycle for dissolving an ionic compound?
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What determines whether the enthalpy of solution is exothermic or endothermic?
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What is entropy a measure of?
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How is the entropy change of a reaction calculated from absolute entropy values?
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What is the equation that relates Gibbs free energy change to enthalpy change and entropy change?
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How is a standard enthalpy change at 298 K symbolised?
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In the equation q = mcΔT, what does m represent?
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When using enthalpies of formation to calculate the enthalpy change of a reaction, what is the general formula?
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In a reaction, what happens to bonds in the reactants and what happens to form products?
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What is lattice enthalpy of formation?
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How does ion size affect the magnitude of enthalpy of hydration?
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What are the units of entropy?
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What condition must be met for a reaction to be thermodynamically feasible in terms of Gibbs free energy?
Take Energetics and Thermodynamics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Exothermic change vs Endothermic change
Exothermic change: a process transferring heat from the system to the surroundings. Endothermic change: a process transferring heat from the surroundings to the system.
Enthalpy of hydration vs Enthalpy of solution
Enthalpy of hydration: the enthalpy change when gaseous ions become aqueous ions. Enthalpy of solution: the enthalpy change when one mole of ionic solid dissolves in water.
Enthalpy change vs Entropy change
Enthalpy change: heat energy transferred under constant pressure. Entropy change: change in dispersal of energy and particles.
Questions from this topic
Each one with the model answer underneath.
- 1
What is enthalpy change (ΔH)?
Model answer
The heat taken in or given out when pressure is held constant
- 2
Under what conditions is enthalpy change measured?
Model answer
Constant pressure
- 3
What pressure is specified for standard conditions?
Model answer
100 kPa
- 4
Besides pressure, what else must be stated for standard conditions?
Model answer
A temperature (e.g. 298 K)
- 5
How is a standard enthalpy change at 298 K symbolised?
Model answer
ΔH°₂₉₈ (with the theta symbol and temperature subscript)
- 6
What does the term exothermic mean in relation to a reaction?
Model answer
A reaction that releases heat energy to the surroundings (negative ΔH)
What is inside Levo
Six ways to work the same material.
Energetics and Thermodynamics revision questions
- Is Energetics and Thermodynamics examined at AS in AQA Chemistry?
- Yes. It sits in Papers 1 and 3, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Energetics and Thermodynamics cover in AQA AS-Level Chemistry?
- 4 subtopics: enthalpy change and standard conditions, calorimetry and heat change calculations, hess's law and enthalpy cycles and mean bond enthalpies. Each one has its own page with questions and model answers.
- How is Energetics and Thermodynamics organised?
- By the AQA 7405 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Energetics and Thermodynamics, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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