(a) State Le Chatelier’s principle
(b) Use Le Chetelier’s principle to deduce the conditions that favour a high yield of ammonia in the Haber process
(c) Give the chemical test for ammonia.
(d) State what would be observed when aqueous ammonia solution is added to:
(i) zinc chloride solution, (ii) copper (II) tetraoxosulohate (V) solution
(e) Explain why the H — N — H bond angle in ammonia is less than that of H — C — H in methane
(f) Give two uses of ammonia.
Explanation
(a) Le Chateller's principles states that a system at equilibrium will change in such a way as to nullify any change about any factors affecting the equilibrium, e.g temperature.
(b) For the Haber process, 3H2(g) + N2\(_{(g)}\) 2NH\(_{3(g)}\) \(\Delta\)H. Increase in pressure favours the yield of ammonia because the reaction flows in the direction of the less number of moles. Decrease in temperature favours the exothermic process as the Haber process. Increase in the number of moles of the reactants will favour the production of ammonia.
(c) Ammonia form white fumes of ammonium chloride, when it is brought in contact with hydrogen chloride solution on rod dipped into it.
(d)
| Test | Observation |
|
(i) Ammonia solution is added to a clear solution of zinc chloride (ii) Ammonia solution is added to a clear solution of solution of copper(II) tetraoxosulphate (VI) solution |
White gelatinous precipitate which became soluble in excess of the ammonia solution. Precipate is soluble forming deep blue solution |
(e) The electron cloud formed by the unsharedl pair in NH\(_3\) spread out over a greater volume than that of the three pair connected to hydrogen atoms. This would tend to force the bonding pairs closer to one another and thereby reduce the bond angle to less than the bond angle in the tetrahedral methane.
(f) Ammonia is used to make trioxonitrate (V) acid. Ammonia solution is used in laundry work. It removes temporary hardness by precipitating the Calcium ion as CaCO\(_3\).