Find the weight of chlorine gas produced when one ampere current is passed for 15 minutes through molten sodium chloride. (Atomic mass of chlorine= 35.5).

Time(t) =15minutes=15x60=900 seconds; current=1ampere.

Reaction: ${\mathrm{Cl}}^{-}-1e^{-}⟶1/2{\mathrm{Cl}}_2$ 

Eq. wt. of ${\mathrm{Cl}}_2=\text{ At. wt. of }\mathrm{Cl}/1=35.5/1=35.5.$ 

Electrochemical equivalent, $Z=\text{ g.eq.wt. of }\mathrm{Cl}/96500\mathrm{C}=35.5/96500$. We know, $\mathrm{wt}=\mathrm{Zx}$ current in amperes X time in seconds 

$=(35.5\times 1\times 15\times 60)/96500)=0.331\mathrm{g}$