A sealed reaction vessel contains carbon monoxide and oxygen.
The gases react when heated.
2CO(g)+O2(g)→2CO2(g)2\mathrm{CO}(g) + \mathrm{O_2}(g) \rightarrow 2\mathrm{CO_2}(g)2CO(g)+O2(g)→2CO2(g)
| Substance | Mass in the vessel in g |
|---|---|
| carbon monoxide, CO\mathrm{CO}CO | 5.60 |
| oxygen, O2\mathrm{O_2}O2 | 3.20 |
Relative atomic masses: C = 12, O = 16
The Avogadro constant = 6.02 × 1023 per mole
Calculate the total number of atoms in the vessel before the reaction.
Calculate the number of carbon dioxide molecules formed when the reaction is complete.
Explain why the total number of molecules changes during the reaction even though the total number of atoms does not change.
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.