Car antifreeze contains a compound that is made of carbon, hydrogen and oxygen only. Analysis shows that the compound contains 38.7% carbon, 9.7% hydrogen and 51.6% oxygen by mass.
Relative atomic masses: H = 1, C = 12, O = 16, Mg = 24, S = 32
State what is meant by the term empirical formula.
Determine the empirical formula of the compound. You must show your working.
The relative formula mass (MrM_{r}Mr) of the compound is 62. Deduce the molecular formula of the compound. You must show your working.
Epsom salts are hydrated magnesium sulfate, MgSO4⋅xH2O\mathrm{MgSO_{4}{\cdot}xH_{2}O}MgSO4⋅xH2O. When the crystals are heated, the water is given off and anhydrous magnesium sulfate, MgSO4\mathrm{MgSO_{4}}MgSO4, remains. Describe how a student could carry out an experiment to find the value of x, and explain how the results would be used to calculate x.
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.