Question

$3.17gm$ of a substance was deposited by the flow of $0.1$ mole of electrons. The equivalent weight of the substance is:

• A. $3.17$
• B. $0.317$
• C. $317$
• D. $31.7$

Answer 1

Answer: (D)

$31.7$

Given,

$3.17gm$ of substance was deposited by flow

$0.1$ mole of $e^{-}$

Charge of $1e^{-}=1.6\times {10}^{-19}C$

Now, $0.1$ mole of $e^{-}=0.1\times 6.023\times {10}^{23}{e}^{-}s$

$\therefore$ Total amount of charge flown by $0.1$ mole of $e^{-}$

$=0.1\times 6.023\times {10}^{23}\times 1.6\times {10}^{-19}C$

$=9636.8C$

We know, $1F=96500C$

$\therefore 9636.8C=\frac{9636.8}{96500}F=0.09986F$

Also, $F$ is required to deposit $1g$ equivalent of substance.

$\Rightarrow 0.9986F=0.9986g$ equivalent

Now, $g$ equivalent=$\frac{Weightofsubstance}{EquivalentWeightofit}$

$\Rightarrow 0.9986=\frac{3.17}{Eq.Wt}$

$\Rightarrow Eq.Wt=\frac{3.17}{0.9986}\approx \frac{3.17}{0.1}=31.7$