Q10 / 150 · MHT CET 2026 (20 April Shift 1) · Chemistry
What is the quantity of electricity required to produce $8$ g of Mg (molar mass = $24\ \text{g mol}^{-1}$) from $\text{MgCl}_2$ solution ?
- A$0.222$ F
- B$0.444$ F
- Correct answerC$0.666$ F
- D$0.888$ F
Solution
The reduction reaction of magnesium is given by:
$\text{Mg}^{2+} + 2e^{-} \rightarrow \text{Mg}$
From the stoichiometry of the reaction, $1$ mole of Mg requires $2$ moles of electrons, which corresponds to $2\text{ F}$ of electricity.
Number of moles of Mg to be produced = $\dfrac{\text{Mass}}{\text{Molar mass}} = \dfrac{8}{24} = \dfrac{1}{3}\text{ mol}$
Quantity of electricity required = $\dfrac{1}{3} \times 2\text{ F} = \dfrac{2}{3}\text{ F} = 0.666\text{ F}$
Answer: $0.666$ F
$\text{Mg}^{2+} + 2e^{-} \rightarrow \text{Mg}$
From the stoichiometry of the reaction, $1$ mole of Mg requires $2$ moles of electrons, which corresponds to $2\text{ F}$ of electricity.
Number of moles of Mg to be produced = $\dfrac{\text{Mass}}{\text{Molar mass}} = \dfrac{8}{24} = \dfrac{1}{3}\text{ mol}$
Quantity of electricity required = $\dfrac{1}{3} \times 2\text{ F} = \dfrac{2}{3}\text{ F} = 0.666\text{ F}$
Answer: $0.666$ F
Hence, the correct answer is option: 'C'.