Question

State one observation for each of the following :-
0) A small piece of zinc is added to dilute hydrochloric acid.
ii)
Addition of excess of ammonium hydroxide into copper sulphate solution.
iii) Action of conc. H, SO, on hydratet copper sulphate.
iv) Barium chloride solution is mixed with sodium sulphate solution.
v) Dilute hydrochloric acid is added to sodium thiosulphate.​

Answer 1

Answer:

(i)Zinc reacts with dilute HCl to give a metallic zinc chloride with the evolution of hydrogen gas.

(ii)When ammonium hydroxide is added in the solution of copper sulfate drop-wise, a pale blue precipitate of copper hydroxide is obtained. The equation for this follows: When ammonium hydroxide is added in excess, the precipitate dissolves and gives a deep blue solution of tetraammine copper (II) sulphate

(iii)Concentrated Sulphuric acid acts as dehydrating agent and removes the water of crystallisation from hydrated copper sulphate to produce anhydrous copper(II) sulfate. The reaction is reversible. Hydrated copper sulphate is blue in colour. Anhydrous copper sulphate is colourless/white.

(iv) On mixing a solution of barium chloride with sodium sulphate, a white precipitate of barium sulphate is immediately formed. These reactions are ionic in nature. The reactants changes into ions when dissolved in water and there is an exchange of ions in solution.

(v) Dilute Hydrochloric acid is added to Sodium thiosulphate. Dil. HCl reacts with thiosulphates to produce sulphur dioxide and yellow sulphur is precipitated.

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