Question 5(iv)
Give reasons
(a) Liquid ammonia is used as a refrigerant in ice plants.
(b) Only all-glass apparatus should be used for the preparation of nitric acid by heating concentrated sulphuric acid and potassium nitrate.
(c) A piece of wood becomes black when concentrated sulphuric acid is poured on it.
(a) Liquid ammonia is a clear, colourless liquid under pressure. It evaporates rapidly and produces cooling effect. Moreover, Ammonia is environmentally compatible, has superior thermodynamic properties and its leaks are easily detectable due to its recognizable odour. All these reasons make liquid ammonia a good refrigerant.
(b) All glass apparatus is used in the laboratory preparation of nitric acid since the vapours of nitric acid being highly corrosive attack rubber, cork, etc.
(c) A piece of wood becomes black because of the dehydrating property of sulphuric acid. It readily removes elements of water from other compounds.
[C6H10O5]n 6[C]n + 5[H2O]n