Question

4.5 g of Al (atomic mass 27 amu) is deposited at cathode from $A{l}^{3+}$ solution by a certain quantity of charge. The volume of $H_2$ produced at STP from 11+ ions in solution by the same quantity of charge will be ?

• A. 11.2 L
• B. 5.6 L
• C. 44.8 L
• D. 22.4 L

Answer 1

The correct option is B 5.6 L

From Faraday's second law of electrolysis,

$\frac{w_{Al}}{w_H}=\frac{E_{Al}}{E_H}$

$E_{Al}=\frac{27}{3}=9g$

$E_H=1g$

$w_{Al}=4.5g$

$w_H=?$

$\therefore \frac{4.5}{w_H}=\frac{9}{1}$

$\Rightarrow w_H=0.5g$

As we know,

At STP, the volume of $1$ mole of a gas is $22.4L$

Therefore,

Volume of $2g$ of hydrogen $=22.4L$

Volume of $0.5g$ of hydrogen $=\frac{22.4}{2}\times 0.5=5.6L$

Hence, the correct option is $\text{B}$