A student adds 0.35 g of lithium to excess water and collects the hydrogen gas in a gas syringe.
2Li(s)+2H2O(l)→2LiOH(aq)+H2(g)2\mathrm{Li(s)} + 2\mathrm{H_{2}O(l)} \rightarrow 2\mathrm{LiOH(aq)} + \mathrm{H_{2}(g)}2Li(s)+2H2O(l)→2LiOH(aq)+H2(g)
Relative atomic mass: Li = 7. The volume of one mole of any gas at room temperature and pressure is 24 000 cm3\mathrm{cm^{3}}cm3.
Calculate the maximum volume, in cm3\mathrm{cm^{3}}cm3, of hydrogen that could form at room temperature and pressure.
The student collects 540 cm3\mathrm{cm^{3}}cm3 of hydrogen.
Calculate the volume collected as a percentage of the maximum volume.
Suggest two reasons why the volume collected is less than the maximum volume.
The solution is made up to 250 cm3\mathrm{cm^{3}}cm3 with water. Calculate the concentration, in mol dm−3\mathrm{mol\,dm^{-3}}moldm−3, of lithium hydroxide in the solution. Assume all 0.35 g of lithium reacted.
Write the half equation for the change that happens to lithium atoms and explain why lithium is described as being oxidised.
41 exam-style questions on Edexcel GCSE Chemistry 7.1 Group 1, covering 7.1.1 Classifying elements by group in the periodic table and 7.1.2 Properties and reactions of the alkali metals. Each one has a worked solution and a mark scheme showing where the marks go.