(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).
Explanation
(a) (i) 2SO\(_2\) + O\(_2\) + 2H\(_2\)O \(\to\) 2H\(_2\)SO\(_4\)
(ii) Use BaCl\(_2\) solution it gives white insoluble solid / precipitate to form bariumtetraoxosulphate (VI)
OR
Add a solution of bariumtrioxonitrate (V), a white precipitate of bariumtetraoxosulphate (VI) is formed
(iii) I. C\(_2\)H\(_2\)O\(_4\) \(\frac{-H_2O}{H_2SO_4}\) CO + CO\(_2\)
(iv) I. H\(_2\)SO\(_4\) is acting as a dehydrating agent
II. Cu + 2H\(_2\)SO\(_4\) → SO\(_2\) + CuSO\(_4\) + 2H\(_2\)O
II. H\(_2\)SO\(_4\) is acting as an oxidizing agent
(b) (i) Water is referred to as a universal solvent because it is able to dissolve more substances than any other liquid. This has to do with the polarity of each water molecule. The hydrogen side of each water molecule carries a slight positive electric charge, while the oxygen side carries a slight negative electric charge and this helps water dissociate ionic compounds into their positive and negative ions.
(ii) Water will turn cobalt (II) chloride paper from blue to pink / anhydrous copper (II) tetraoxosulphate (VI) crystals from white to blue
(c) (i) CO / Carbon (II) Oxide
(ii) Because it is combustible / can be used as fuel
(d) (i) coke
(ii) coal tar / ammoniacal liquor / pitch
(iii) coal gas
(e) (i) C(s) + O\(_{2(g)}\) →CO\(_{2(g)}\)
(ii) I. - It is odourless
- It is colourless
- It is denser than air
- It is soluble in water
- It is a gas at room temperature
- It is easily compressible
(ii) It does not support combustion
It reacts with red hot carbon (to form CO)
it is weakly acidic in water
it reacts with alkali (to form trioxocarbonate (IV) ) / turns lime water milky
Reacts with burning magnesium