A aqueous solution of `NaCl` on electrolysis gives `H_(2)(g), Cl_(2)(g)`, and `NaOH` according to the reaction :
`2Cl^(-)(aq)+2H_(2)Orarr 2OH^(-)(aq)+H_(2)(g)+Cl_(2)(g)`
A direct current of 25A with `62%` efficiency is passed through 20 L NaCl solution (`20%` by weight). (2) How long will it take to form 1kg `Cl_(2)`?

Explanation

According to Faraday's first law, `W=ZIt" …(1)"`
Current efficiency `=62%=0.62`
Effective electric current (I) `=25xx0.62A`
Mass of `Cl_(2)=10^(3)g therefore" Z for "Cl_(2)=("eq. weight")/(96500)=(35.5)/(96500)`
`"Substituting in equation (1), "10^(3)=(35.5)/(96500)xx25xx0.62xxt`
`"or, "t=(10^(3)xx96500)/(35.5xx25xx0.62)="175375.83 sec = 48.71 hrs"`