Question

A current of $\text{5}\text{.0}\text{A}$ flows for $\text{4}\text{.0}\text{h}$ through an electrolytic cell containing a molten salt of metal M. This results in deposition of $\text{0}\text{.25}\text{mol}$ of the metal $\text{M}$ at the cathode. The oxidation state of $\text{M}$ in the molten salt is $\text{+}\text{x}$ . the value of ' $\text{x}$ ' is ( $\text{1}\text{Faraday}\text{=}\text{96000}\text{C}$ $mo{l}^{-1}$ )

Answer 1

Answer: 3

$\text{I}=5.0\text{ A},\text{ t}=4.0\text{ h}$

Moles of metal deposited $=\frac{1}{4}$

$Q=5.0\times 4\times 60\times 60$ coulombs

Charge in faradays

$\text{Q}=\frac{5\times 4\times 60\times 60}{96000}=0.75\text{F}$

$\frac{1}{4}$ moles of metal will be deposited by $\frac{3}{4}$ F charge required

So, for 1 mole, $\frac{3}{4}\times 4=3F$

Oxidation $=+3$