Question

On passing a current through molten KCl, $19.5g$ of potassium is deposited. If the same quantity electricity is passed through molten $AlC{l}_3$ is:

• A. 4.5 g
• B. 9 g
• C. 13.5 g
• D. 2.7 g

Answer 1

The correct option is A 4.5 g

The reactions involved are,

$K+e^{-}\to K$

$Al3+3e^{-}\to Al$

Aluminium requires 3 times the amount of electricity to deposit one mole,

Moles of K deposited $=\frac{19.5}{39}=0.5$

Moles of Al deposited $=\frac{0.5}{3}=\frac{1}{6}$

Mass of Al deposited $=27\times \frac{1}{6}$

$=4.5g$