a)(i) Give two uses of ammonia. (ii) Name the process by which ammoniacal liquor can be obtained from coal and list two other products of the reaction (iii)...
(ii) Name the process by which ammoniacal liquor can be obtained from coal and list two other products of the reaction
(iii) What type of reaction is involved in the conversion of ammoniacal liquor to (NH\(_4\))\(_2\)SO\(_4\) by dilute H\(_2\)SO\(_4\)?
(iv) Sketch and label an energy profile diagram to show the effect of presence of Pt/Rh on the reaction represented by the following equation: 4NH\(_3\) + 5O\(_2\) \(\to\) 6H\(_2\)O + 4NO; \(\Delta\)H = —907 kJmol\(^1\)
(b) Rock salt is an impure form of sodium chloride.
(i) Outline a suitable procedure for preparing a pure sample of sodium chloride from rock salt.
(ii) State two methods that can be used to prepare chlorine from rock salt. Write an appropriate equation in each case.
(c) Lead pigments were used in a water colour painting which turned black after prolonged exposure to an air pollutant. The original colour was restored by using H\(_2\)O\(_2\) which converted the black substance to a simple, white lead (II) salt.
(i) Which pollutant turned the painting black?
(ii) Write the formula of the black substance
(iii) What is the white salt?
(iv) State the role of H\(_2\)O in the restoration process.
(a)(i) Two uses of ammonia are:
Manufacture of fertilizers such as ammonium sulphate and ammonium nitrate.
Manufacture of trioxonitrate(V) acid, i.e. nitric acid.
(a)(ii) Ammoniacal liquor is obtained by the destructive distillation of coal.
Two other products are:
Coke
Coal tar
Coal gas is also produced.
(a)(iii) The reaction is a neutralisation (acid-base) reaction.
\(2NH_3 + H_2SO_4 \rightarrow (NH_4)_2SO_4\)
(a)(iv) Energy profile diagram for the reaction:
The reaction is exothermic because the products are at a lower energy level than the reactants. Pt/Rh lowers the activation energy but does not change the value of \(\Delta H\).
(b)(i) Procedure for preparing pure sodium chloride from rock salt:
Crush the rock salt and dissolve it in water.
Filter the mixture to remove insoluble impurities such as sand.
Evaporate the filtrate until it is nearly saturated.
Allow the solution to cool so that sodium chloride crystals form.
Filter, wash the crystals with a little cold distilled water and dry them.
(b)(ii) Two methods of preparing chlorine from rock salt are:
Manufacture of fertilizers such as ammonium sulphate and ammonium nitrate.
Manufacture of trioxonitrate(V) acid, i.e. nitric acid.
(a)(ii) Ammoniacal liquor is obtained by the destructive distillation of coal.
Two other products are:
Coke
Coal tar
Coal gas is also produced.
(a)(iii) The reaction is a neutralisation (acid-base) reaction.
\(2NH_3 + H_2SO_4 \rightarrow (NH_4)_2SO_4\)
(a)(iv) Energy profile diagram for the reaction:
The reaction is exothermic because the products are at a lower energy level than the reactants. Pt/Rh lowers the activation energy but does not change the value of \(\Delta H\).
(b)(i) Procedure for preparing pure sodium chloride from rock salt:
Crush the rock salt and dissolve it in water.
Filter the mixture to remove insoluble impurities such as sand.
Evaporate the filtrate until it is nearly saturated.
Allow the solution to cool so that sodium chloride crystals form.
Filter, wash the crystals with a little cold distilled water and dry them.
(b)(ii) Two methods of preparing chlorine from rock salt are:
