Explain the reason why:
(i) HCl gas fumes in moist air.
(ii) Dilute HCl cannot be concentrated beyond 22.2% by distillation.
(iii) Dilute acids are stronger electrolytes as compared to concentrated acid.
(iv) Liquid ammonia has no action on litmus while liquor ammonia has an effect.
(v) Ammonia is not collected over water.
(vi) Pure nitric acid does not dissolve gold or platinum, but aqua regia dissolves them.
Explain the reason why:
(i) HCl gas fumes in moist air.
(ii) Dilute HCl cannot be concentrated beyond 22.2% by distillation.
(iii) Dilute acids are stronger electrolytes as compared to concentrated acid.
(iv) Liquid ammonia has no action on litmus while liquor ammonia has an effect.
(v) Ammonia is not collected over water.
(vi) Pure nitric acid does not dissolve gold or platinum, but aqua regia dissolves them.
(i) HCl gas fumes in moist air because of its high solubility in water. When HCl dissolves in the water vapour present in the atmosphere, a mist of hydrochloric acid in the form of dense fumes is produced.
(ii) Dilute HCl, when dissolved in water, reaches a constant boiling point of 109.8oC and weight composition of 22.2%. On further distillation, the vapour and the liquid phase of HCl remains the same in terms of composition; hence, it cannot be concentrated beyond 22.2% .
(iii) Dilute acids are stronger electrolytes because on dilution, the ionising capability of the acid increases consequently, i.e. the concentration of H+ ions increases. Due to this, there are higher number of ions for the conduction of electricity. Therefore, dilute acids are stronger electrolytes because of higher concentration of H+ ions.
(iv) Liquid ammonia does not contain OH− ions; therefore, it has no effect on litmus paper. On the other hand, liquor ammonia (solution of ammonia in water) contains OH− ions; hence, it acts as a base. Therefore, liquor ammonia turns red litmus paper blue.
(v) Since ammonia is highly soluble in water, it is not collected over the latter.
(vi) Pure nitric acid alone does not dissolve gold or platinum but aqua regia (which is a mixture of concentrated nitric and hydrochloric acid) can dissolve gold and platinum. On combination, each acid performs a different task. Nitric acid act as powerful oxidising agent. It oxidises conc. HCl to liberate nascent chlorine. The liberation of atomic chlorine forms a soluble compound with gold and platinum.
(i) HCl gas fumes in moist air because of its high solubility in water. When HCl dissolves in the water vapour present in the atmosphere, a mist of hydrochloric acid in the form of dense fumes is produced.
(ii) Dilute HCl, when dissolved in water, reaches a constant boiling point of 109.8oC and weight composition of 22.2%. On further distillation, the vapour and the liquid phase of HCl remains the same in terms of composition; hence, it cannot be concentrated beyond 22.2% .
(iii) Dilute acids are stronger electrolytes because on dilution, the ionising capability of the acid increases consequently, i.e. the concentration of H+ ions increases. Due to this, there are higher number of ions for the conduction of electricity. Therefore, dilute acids are stronger electrolytes because of higher concentration of H+ ions.
(iv) Liquid ammonia does not contain OH− ions; therefore, it has no effect on litmus paper. On the other hand, liquor ammonia (solution of ammonia in water) contains OH− ions; hence, it acts as a base. Therefore, liquor ammonia turns red litmus paper blue.
(v) Since ammonia is highly soluble in water, it is not collected over the latter.
(vi) Pure nitric acid alone does not dissolve gold or platinum but aqua regia (which is a mixture of concentrated nitric and hydrochloric acid) can dissolve gold and platinum. On combination, each acid performs a different task. Nitric acid act as powerful oxidising agent. It oxidises conc. HCl to liberate nascent chlorine. The liberation of atomic chlorine forms a soluble compound with gold and platinum.
