A compound contains 85.7% carbon and 14.3% hydrogen by mass. Use C=12\mathrm{C} = 12C=12 and H=1\mathrm{H} = 1H=1. What is its empirical formula?
CH\mathrm{CH}CH
CH2\mathrm{CH_{2}}CH2
C2H\mathrm{C_{2}H}C2H
C2H3\mathrm{C_{2}H_{3}}C2H3
55 exam-style questions on Edexcel GCSE Chemistry 2.6 Calculations involving masses, covering 2.6.1 Relative formula mass and percentage composition, 2.6.2 Empirical and molecular formulae, 2.6.3 Conservation of mass, 2.6.4 Reacting masses and concentration in g dm⁻³, 2.6.5 The mole and the Avogadro constant, and 2.6.6 Limiting reactants and stoichiometry. Each one has a worked solution and a mark scheme showing where the marks go.