Question

A current of $4.0A$ is passed for 5 hours through $1L$ of $2M$ solution of nickel nitrate using two nickel electrodes. The molarity of the solution at the end of the electrolysis will be:

• A. $1.6M$
• B. $1.2M$
• C. $2.5M$
• D. $2.0M$

Answer 1

The correct option is A $1.6M$

We have,

$Q=It$

$=$ $\left(4.0A\right)(5\times 60\times 60s)$

$=72000$C

Amount of $Ni$ deposited=$=\frac{72000}{2\times 96500C{mol}^{-1}}=0.373$mol

Amount of ${Ni}^{2+}$ left behind= $2$mol-$0.373$mol=$1.62$mol

Molarity of solution $=$ $\frac{1.62}{1L}=1.62$ mol$L^{-1}$