Chemists use the Avogadro constant to link the mass of a substance to the number of particles it contains.
Relative atomic masses: H = 1, He = 4, C = 12, S = 32, Au = 197
The Avogadro constant = 6.02 × 1023 per mole
A small diamond is made of pure carbon and has a mass of 0.100 g. Calculate the number of carbon atoms in the diamond. Give your answer to three significant figures.
Solid sulfur is made of molecules with the formula Sn\mathrm{S_{n}}Sn. A sample containing 1.00 × 1022 sulfur molecules has a mass of 4.25 g. Determine the value of n. You must show your working.
A student says that 1.0 g of hydrogen gas, H2\mathrm{H_{2}}H2, and 1.0 g of helium gas, He, contain the same number of atoms. Determine whether the student is correct. You must show your working.
Calculate the mass, in grams, of one atom of gold.
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.