(a) (i) Write an equation for the reaction by which sulphur dioxide in solution could be converted to tetraoxosulphate (VI) acid.
(ii) State one test to confirm the conversion of sulphur dioxide to tetraoxosulphate (VI) acid.
(iii) State the reaction of concentrated tetraoxosulphate (VI) acid with:
(I) oxalic acid;
(II) copper.
(iv) What property of concentrated tetraoxosulphate (VI) acid does each of the reactions stated in (a)(iii) illustrate?
(b) (i) Explain briefly why water is referred to as a universal solvent.
(ii) Give one chemical test for water.
(c) (i) What is the major component of synthetic gas?
(ii) Give one reason why synthetic gas is not a major source of air pollution.
(d) Name one product of destructive distillation of coal that is:
(i) solid;
(ii) liquid;
(iii) gas.
(e) (i) Write a balanced chemical equation for the complete combustion of carbon.
(ii) State one:
(I) physical;
(II) chemical property of the products in (e)(i).
(a)(i) \(SO_2 + Cl_2 + 2H_2O \rightarrow H_2SO_4 + 2HCl\) (sulphur dioxide is oxidized to tetraoxosulphate(VI) acid).
(ii) Add barium chloride solution followed by dilute HCl: a white precipitate of BaSO4 (insoluble in the acid) confirms the tetraoxosulphate(VI) ion.
(iii) Concentrated H2SO4 with:
- Oxalic acid: it dehydrates the acid. \((COOH)_2 \rightarrow CO + CO_2 + H_2O\)
- Copper (hot): it oxidizes copper. \(Cu + 2H_2SO_4 \rightarrow CuSO_4 + SO_2 + 2H_2O\)
(iv) With oxalic acid it acts as a dehydrating agent; with copper it acts as an oxidizing agent.
(b)(i) Water is called a universal solvent because it dissolves a greater number of substances than any other solvent, owing to its polar nature.
(ii) Add the liquid to white anhydrous copper(II) tetraoxosulphate(VI): it turns blue if water is present (or anhydrous cobalt(II) chloride turns from blue to pink).
(c)(i) The major components of synthesis gas are carbon(II) oxide and hydrogen.
(ii) It burns completely and cleanly to give carbon(IV) oxide and water, producing no soot or sulphurous fumes.
(d) From destructive distillation of coal: (i) solid: coke; (ii) liquid: coal tar (or ammoniacal liquor); (iii) gas: coal gas.
(e)(i) \(C + O_2 \rightarrow CO_2\)
(ii) Carbon(IV) oxide: (I) physical: it is a colourless gas, denser than air; (II) chemical: it turns lime water milky and does not support combustion.
(a)(i) \(SO_2 + Cl_2 + 2H_2O \rightarrow H_2SO_4 + 2HCl\) (sulphur dioxide is oxidized to tetraoxosulphate(VI) acid).
(ii) Add barium chloride solution followed by dilute HCl: a white precipitate of BaSO4 (insoluble in the acid) confirms the tetraoxosulphate(VI) ion.
(iii) Concentrated H2SO4 with:
- Oxalic acid: it dehydrates the acid. \((COOH)_2 \rightarrow CO + CO_2 + H_2O\)
- Copper (hot): it oxidizes copper. \(Cu + 2H_2SO_4 \rightarrow CuSO_4 + SO_2 + 2H_2O\)
(iv) With oxalic acid it acts as a dehydrating agent; with copper it acts as an oxidizing agent.
(b)(i) Water is called a universal solvent because it dissolves a greater number of substances than any other solvent, owing to its polar nature.
(ii) Add the liquid to white anhydrous copper(II) tetraoxosulphate(VI): it turns blue if water is present (or anhydrous cobalt(II) chloride turns from blue to pink).
(c)(i) The major components of synthesis gas are carbon(II) oxide and hydrogen.
(ii) It burns completely and cleanly to give carbon(IV) oxide and water, producing no soot or sulphurous fumes.
(d) From destructive distillation of coal: (i) solid: coke; (ii) liquid: coal tar (or ammoniacal liquor); (iii) gas: coal gas.
(e)(i) \(C + O_2 \rightarrow CO_2\)
(ii) Carbon(IV) oxide: (I) physical: it is a colourless gas, denser than air; (II) chemical: it turns lime water milky and does not support combustion.
