Car airbags inflate with nitrogen gas made when sodium azide, NaN3\mathrm{NaN_{3}}NaN3, decomposes.
2NaN3(s)→2Na(s)+3N2(g)\mathrm{2NaN_{3}(s)} \rightarrow \mathrm{2Na(s)} + \mathrm{3N_{2}(g)}2NaN3(s)→2Na(s)+3N2(g)
One mole of any gas occupies 24 dm3\mathrm{dm^{3}}dm3 at room temperature and pressure. Relative formula mass: NaN3=65\mathrm{NaN_{3}} = 65NaN3=65
State Avogadro's law.
Calculate the mass of sodium azide needed to produce 72 dm3\mathrm{dm^{3}}dm3 of nitrogen at room temperature and pressure.
The sodium formed is dangerous, so the airbag also contains potassium nitrate. This reacts with the sodium.
10Na(s)+2KNO3(s)→K2O(s)+5Na2O(s)+N2(g)\mathrm{10Na(s)} + \mathrm{2KNO_{3}(s)} \rightarrow \mathrm{K_{2}O(s)} + \mathrm{5Na_{2}O(s)} + \mathrm{N_{2}(g)}10Na(s)+2KNO3(s)→K2O(s)+5Na2O(s)+N2(g)
Calculate the total volume of nitrogen, at room temperature and pressure, produced from the amount of sodium azide in (b) when both reactions are complete.
In a different experiment, 40 cm3\mathrm{cm^{3}}cm3 of carbon monoxide is mixed with 30 cm3\mathrm{cm^{3}}cm3 of oxygen and ignited.
2CO(g)+O2(g)→2CO2(g)\mathrm{2CO(g)} + \mathrm{O_{2}(g)} \rightarrow \mathrm{2CO_{2}(g)}2CO(g)+O2(g)→2CO2(g)
Determine the volume of each gas present after the reaction. All volumes are measured at the same temperature and pressure.
51 exam-style questions on Edexcel GCSE Chemistry 6.2 Quantitative analysis, covering 6.2.1 Concentration in mol dm⁻³ and titration calculations, 6.2.2 Percentage yield and why actual yield falls short, 6.2.3 Atom economy of a reaction, 6.2.4 Choosing a reaction pathway, and 6.2.5 Molar volume of gases and Avogadro's law. Each one has a worked solution and a mark scheme showing where the marks go.