Question

What happens when ionic hydrides of s-block elements in molten state are electrolysed?

Options

• Hydride ion migrates at cathode

• Dihydrogen is liberated at cathode

• Hydride ion reforms metal hydride

• Dihydrogen is liberated at anode

Answer 1

Dihydrogen is liberated at anode

Explanation:

When ionic hydrides of s -block elements are subjected to electrolysis, dihydrogen gas is liberated at anode which confirms the existence of hydrogen in the form of hydride ion (H^-). Following reactions takes place:

\[\ce{MH(l) <=> M+ (aq) + H- (aq)}\]

At cathode

\[\ce{M+ (aq) + e- -> M(s)}\]

At anode

\[\ce{2H- (aq) - 2e- -> 2H(g)}\]

\[\ce{H + H -> H2(g)}\]