Question

A current of $10$ amperes flowing for 10 minutes, deposits $3g$ of metal. The equivalent weight of the metal is:

• A. 18.5
• B. 12.5
• C. 48.25
• D. 21.5

Answer 1

The correct option is C 48.25

Given :
$\text{Mass deposited}=3g$
$\text{Current, I}=10A\text{Time, t}=10minutes\text{Time, t}=600s$

By Faraday's First law,
The mass deposited/released of any substance during electrolysis is proportional to the amount of charge passed into the electrolyte.

$W\propto Q$
$W=ZQ$
where,

W: Mass deposited or liberated
Q: Amount of charge passed
Z: Electrochemical equivalent of the substance
Since,
$Z=\frac{E}{96500}$

$W=\frac{E}{96500}\times Q$
where,
E is Equivalent weight

$\text{Charge, Q}=I\times t$
$Q=10\times 600$
Hence,
$W=Z\times i\times t$
$3=\frac{E}{96500}\times 10\times 600$

$\therefore E=\left(\frac{3\times 96500}{10\times 600}\right)=48.25$