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A-Level Chemistry calculations
A-Level Chemistry is the two-year course taken in Years 12 and 13 in England, Wales and Northern Ireland. The A-Level questions roughly follow major exam boards.
How to prepare here
- Kc and Kp have units at A-Level, but the K introduced later on is dimensionless.
- Read the Book page on a topic first if a question type is new to you, then try its worked example.
Conventions
- Give answers to the same number of significant figures as the least precise data (usually 3).
- Units: SI with dm³ and mol dm⁻³, as on the AQA data sheet.
- Constants as on the data sheet: R = 8.31, NA = 6.022 × 10²³.
A-Level (AQA) question types (34)
- ΔG from ΔH and ΔS
- Activation energy from two rate constants
- pH of a weak acid
- Buffer pH (Henderson–Hasselbalch)
- Moles of an ideal gas
- Hess's law from enthalpies of formation
- E°cell from reduction potentials
- Enthalpy of combustion from a calorimetry experiment
- Enthalpy of neutralisation
- ΔfH from enthalpies of combustion
- ΔH from mean bond enthalpies
- An unknown bond enthalpy from ΔH
- Born–Haber cycle: lattice enthalpy of NaCl
- Born–Haber cycle: lattice enthalpy of MgCl₂
- ΔS from standard entropies
- Temperature at which a reaction becomes feasible
- ΔG from enthalpies of formation and entropies
- Reacting masses: iron from iron(III) oxide
- Percentage yield of an ester
- Atom economy
- Titration: sodium hydroxide against sulfuric acid
- Back titration: purity of calcium carbonate
- Volume of gas from a reacting mass
- Relative molecular mass of a volatile liquid
- Water of crystallisation
- Making and diluting a standard solution
- Number of atoms in a mass of compound
- Empirical formula from the masses of each element
- Kc and its units for the Haber process
- Kc from equilibrium amounts and volume
- Kc from initial amounts and one equilibrium amount
- An equilibrium concentration from Kc
- Kp from equilibrium amounts and total pressure
- Kp and its units for the Haber process
Book pages for this level
Plus 24 reagents to drill in the reagent trainer.