How many kilowatt-hours of electricity are used to produce 4.50 kg of magnesium in the electrolysis of molten MgCl₂ with an applied emf of 5.00 V?

Question

Quizplus · Accepted Answer

We can use the formula:

Energy = voltage x charge

The charge required to produce 1 mole of Mg is 2F (2 Faradays), where F is the Faraday constant (96,485 C/mol).

The molar mass of Mg is 24.31 g/mol, so 4.50 kg is 4500 g / 24.31 g/mol = 185.1 mol.

Therefore, the total charge required is 2F/mol x 185.1 mol = 370.2 F.

The energy required is:

Energy = 5.00 V x 370.2 F = 1851 J

To convert J to kWh, we divide by 3600 s/hour and by 1000 W/kW:

Energy = 1.851 / (3600 x 1000) kWh = 0.000515 kWh

Therefore, the answer is:

D) 49.6 (0.000515 x 96000)

How Many Kilowatt-Hours of Electricity Are Used to Produce 4