Question

How many Faradays of electricity are required to deposit 10 g of calcium from molten calcium chloride using inert electrodes? (molar mass of calcium = 40 g $mo{l}^{-1})$

• A. 0.5 F
• B. 1 F
• C. 0.25 F
• D. 2 F

Answer 1

Answer: (A)

0.5 F

$C{a}^{2+}+2e^{-}\to Ca$

Number of moles of $Ca=\frac{10g}{40g/mol}=0.25mol$

$1$ mole $Ca$ requires $=2$ moles of electrons $=2$ faradays of electricity.

$0.25$ mole $Ca=2\times 0.25=0.50$ moles of electrons $=0.5$ faradays of electricity.

Hence, 0.5 Faradays of electricity are required to deposit $10$ g of calcium from molten calcium chloride using inert electrodes.