Question

The colour of a solution of ferric chloride acidified with dil. sulphuric acid remains unchanged when hydrogen from a woulfe's bottle is passed through it; but the acidified ferric chloride solution becomes colourless if a piece of granulated zinc is added to it.--Explain.​

Answer 1

(a) Molecular hydrogen is not so reactive as nascent hydrogen. Zinc reacts with the acid to produce nascent hydrogen which reduces ferric chloride into ferrous chloride.

(b) Sodium hydride, NaH, is an electrovalent compound in which dydrogen is present as an anion, Hɵ. On electrolysis, it is discharged at anode.

NaH↔Na⊕+Hɵ

At cathode: Na++eɵ→Na

At anode: Hɵ→H+eɵ

2H→H2↑