Relative atomic masses: H=1\mathrm{H} = 1H=1, C=12\mathrm{C} = 12C=12, N=14\mathrm{N} = 14N=14, Na=23\mathrm{Na} = 23Na=23, Cl=35.5\mathrm{Cl} = 35.5Cl=35.5. The Avogadro constant is 6.02×1023 mol−16.02\times10^{23}\,\mathrm{mol^{-1}}6.02×1023mol−1.
Statement 1: A sample of nitrogen gas, N2\mathrm{N_{2}}N2, containing 3.01 × 1023 molecules has a mass of 14.0 g.
Statement 2: The number of methane molecules in 8.0 g of CH4\mathrm{CH_{4}}CH4 equals the number of formula units in 29.25 g of sodium chloride, NaCl\mathrm{NaCl}NaCl.
Statement 3: A methane sample containing 6.02 × 1023 atoms altogether has a mass of 6.4 g.
Which statements are correct?
Statements 1 and 2 only
Statements 2 and 3 only
Statements 1 and 3 only
Statement 1 only
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.