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 mol^-1)

Options

• 0.5 F

• 1 F

• 0.25 F

• 2 F

Answer 1

0.5 F

Explanation:

2 moles of electrons are required to deposit 1 mole of calcium.

Mass of calcium deposited = 10 g, 

Molar mass of calcium = 40 g mol^-1

∴ No. of moles = `10/(40 "g mol"^1)` = 0.25 mol

2F are required for 1 mole of calcium

xF are required for 0.25 mole of calcium 

∴ x = 0.25 × 2 = 0.5 F