A technician has an unlabelled sample of a solid. The solid is either aluminium sulfate, Al2(SO4)3\mathrm{Al_2(SO_4)_3}Al2(SO4)3, or iron(III) sulfate, Fe2(SO4)3\mathrm{Fe_2(SO_4)_3}Fe2(SO4)3.
Analysis shows that sulfur makes up 24.0% of the mass of the solid.
The relative atomic masses are shown in the table.
| Element | Al | Fe | S | O |
|---|---|---|---|---|
| ArA_rAr | 27 | 56 | 32 | 16 |
Calculate the percentage by mass of sulfur in each of the two compounds.
Show your working.
Identify the compound in the sample.
142 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.