A student burns 4.6 g of sodium in oxygen gas. The only product is 6.2 g of an oxide of sodium.
(relative atomic masses: O = 16, Na = 23)
Which balanced equation is consistent with these masses?
2Na+O2→Na2O22\mathrm{Na} + \mathrm{O_{2}} \rightarrow \mathrm{Na_{2}O_{2}}2Na+O2→Na2O2
2Na+O2→2NaO2\mathrm{Na} + \mathrm{O_{2}} \rightarrow 2\mathrm{NaO}2Na+O2→2NaO
Na+O2→NaO2\mathrm{Na} + \mathrm{O_{2}} \rightarrow \mathrm{NaO_{2}}Na+O2→NaO2
4Na+O2→2Na2O4\mathrm{Na} + \mathrm{O_{2}} \rightarrow 2\mathrm{Na_{2}O}4Na+O2→2Na2O
230 exam-style questions on Edexcel GCSE Chemistry 1.1 Formulae, equations and hazards, covering 1.1.1 Formulae, word and balanced equations, 1.1.2 Balanced ionic equations, and 1.1.3 Hazard symbols and risk in practical work. Each one has a worked solution and a mark scheme showing where the marks go.