A sample of hydrogen gas, H2\mathrm{H_{2}}H2, has a mass of 4.00 g. The relative particle mass of H2\mathrm{H_{2}}H2 is 2.0. Use the Avogadro constant 6.02 × 1023 mol-1.
Calculate the number of hydrogen molecules 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.