Question

Give reasons for the following changes –

(1) pure water a non-electrolyte – becomes an electrolyte on addition of dil. H₂SO₄

(2) Blue colour of aq. CuSO₄ – turns almost colourless on its electrolysis using Pt electrodes. 

Answer 1

1. Pure water is a non electrolyte. It consists of entirely of molecules. It can be electrically decomposed by Addition of traces of dil. Sulphuric acid. Which dissociates into H¹⁺ and sulphate (SO₄^2- ) ions.

2. If platinum anode is used the blue colour of CuSO₄ solution fades since the blue Cu²⁺ ions which are discharged at the cathode are not replaced or added at the anode.