Chlorine can be liquefied when under pressure and cooled. Liquid chlorine forms a gas when warmed.
Explain what happens to the chlorine molecules when liquid chlorine is warmed to form a gas.
Chlorine reacts with water to form a mixture of hydrochloric acid, HCl\text{HCl}HCl, and hypochlorous acid, HClO\text{HClO}HClO.
Write a chemical equation for this reaction.
Hydrochloric acid reacts with calcium carbonate to form a solution containing calcium chloride.
CaCO3(s)+2HCl(aq)→CaCl2(aq)+H2O(l)+CO2(g) \text{CaCO}_3(\text{s}) + 2\text{HCl}(\text{aq}) \rightarrow \text{CaCl}_2(\text{aq}) + \text{H}_2\text{O}(\text{l}) + \text{CO}_2(\text{g}) CaCO3(s)+2HCl(aq)→CaCl2(aq)+H2O(l)+CO2(g)Crystals of hydrated calcium chloride, CaCl2⋅6H2O\text{CaCl}_2\cdot 6\text{H}_2\text{O}CaCl2⋅6H2O, can be obtained from this solution.
CaCl2+6H2O→CaCl2⋅6H2O \text{CaCl}_2 + 6\text{H}_2\text{O} \rightarrow \text{CaCl}_2\cdot 6\text{H}_2\text{O} CaCl2+6H2O→CaCl2⋅6H2OAn excess of hydrochloric acid is reacted with 0.150 mol0.150\text{ mol}0.150 mol of calcium carbonate.
Show, by calculation, that the maximum theoretical mass of hydrated calcium chloride that can be made is 32.9 g32.9\text{ g}32.9 g. [MrM_rMr of CaCl2⋅6H2O=219\text{CaCl}_2\cdot 6\text{H}_2\text{O} = 219CaCl2⋅6H2O=219]
In an experiment using 0.150 mol0.150\text{ mol}0.150 mol of calcium carbonate, with an excess of hydrochloric acid, the mass of hydrated calcium chloride obtained is 21.5 g21.5\text{ g}21.5 g.
Suggest two reasons why the actual mass obtained is less than the maximum theoretical mass.
80 exam-style questions on Edexcel IGCSE Chemistry Chemical formulae, equations and calculations. Each one has a worked solution and a mark scheme showing where the marks go.