Calculations
Chemistry calculation practice for IChO, UKChO, C3L6 and A-Level. Every given value is a chip carrying its unit; you build the answer by applying formulas and operations, and the feedback shows where your route went wrong. Numbers are fresh every time.
Thermodynamics
- ΔG from ΔH and ΔS
- K from ΔG°
- ΔG° from K
- K from ΔH° and ΔS°
- van 't Hoff: K at a new temperature
- Moles of an ideal gas
- ΔH at another temperature (Kirchhoff)
- Boiling point at reduced pressure
- Entropy change on heating
- Hess's law from enthalpies of formation
- ΔH from a bomb-calorimeter ΔU
- 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
- Enthalpy of solution from a thermodynamic cycle
- Methanol synthesis: K from tabulated data
Kinetics
- First order: concentration after time t
- Activation energy from two rate constants
- Second-order half-life
- Steady state: A ⇌ I → P
- Pre-equilibrium then half-life
- Lindemann–Hinshelwood fall-off
- Michaelis–Menten rate
- Radioactive decay: elapsed time
- ΔG‡ from a rate constant
- Time for a second-order reaction to reach a concentration
- Rate constant from total pressure
- Apparent activation energy of a pre-equilibrium mechanism
- 2NO + O₂: pre-equilibrium with bimolecular steps
- Lindemann mechanism at a given pressure
- From ΔG‡ to a reaction time at another temperature
- Enzyme kinetics from elementary rate constants
Equilibrium
- pH of a weak acid
- Buffer pH (Henderson–Hasselbalch)
- Kp from Kc
- Solubility from Ksp
- pH of a weak base
- 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
- Ksp from a solubility in g dm⁻³
- Solubility with a common ion
- pH of benzoic acid from a weighed sample
- H₂ + I₂ ⇌ 2HI: equilibrium amounts
Electrochemistry
- ΔG° from E°
- Nernst equation
- Mass deposited by electrolysis
- E°cell from reduction potentials
- Equilibrium constant from E°cell
- Electrode potential away from standard conditions
- Latimer diagram: skipping an oxidation state
- Disproportionation constant from a Latimer diagram
- Daniell cell away from standard conditions
Spectroscopy & other
Stoichiometry
- 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
- Oxygen content from combustion analysis
- Iron in a tablet by permanganate titration
- Copper(II) by iodometric titration
- Water hardness by EDTA titration
- Nickel by EDTA back titration