1. The following diagram outlines the manufacture of sodium carbonate by the Solvay Process. (a) Seawater, ammonia and carbon dioxide. See opposite (c) NH4Cl + Ca(OH) 2 NH3 + CaCl2 + H2O +ve -ve Name the reactants in the reaction taking place in the Solvay Tower. In reaction vessel A, carbon dioxide is produced by the following reactions. CaCO3(s)  CaO(s) + CO2(g) DH = ……… C(s) + O3 (g)  CO3 (g) DH = ………. For each reaction, add a sign after the DH to show whether the reaction is endothermic or exothermic. (c) As well as ammonia, a salt and water are produced in reaction vessel B. Write a balanced equation for the production of ammonia in this reaction vessel.

2. (d) The magnesium ions react with the carbonate ions to form a precipitate of magnesium carbonate which can be filtered off. (b) Seawater is cheap raw material. Ammonium chloride is recycled in the plant. (d) The seawater used in the Solvay Process can contain magnesium ions. These can be removed by addition of sodium carbonate solution. Why is sodium carbonate solution suitable for removing contaminant magnesium ions? (e) Using the information in the flow diagram, give two different features of the Solvay Process that make it economical.

3 . Sphalerite is an impure zinc sulphide ore, containing traces of other metal compounds. The flow diagram for the extraction of zinc from this ore is shown below Sulphur dioxide. Displacement OR redox. (c) See diagram. (a) Name gas A (b) Name the type of reaction taking place in reaction vessel B. (c) It is economical to make use of the sulphuric acid produced. Add an arrow to the flow diagram to show how the sulphuric acid could be used in this extraction.