Question

When fused Calcium hydride is electrolyzed, hydrogen in liberated at anode. Why?

Answer 1

Electrolysis:

1. It is a process in which electric current is pass through the molten or aqueous state of an element or a mixture of elements to induced chemical reaction between them.
2. Anode is the positive terminal end and cathode is the negative terminal end of the cell.
3. Oxidation takes place at anode and reduction takes place at cathode.
4. The Hydrogen exists as ${\mathrm{H}}^{-}$ in ${\mathrm{CaH}}_2$. During electrolysis, ${\mathrm{H}}^{-}$ ions are oxidized at anode to liberate ${\mathrm{H}}_2$ and Calcium metal is formed.
5. The reaction can be given as,

At anode : $2{\mathrm{H}}^{-}\to {\mathrm{H}}_2+2{\mathrm{e}}^{-}$

At cathode: ${\mathrm{Ca}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{Ca}$

So, in this electrolytic cell, the only gas liberated is hydrogen.