How many kilowatt-hours of electricity are used to produce 3.00 kg of magnesium in the electrolysis of molten MgCl₂ with an applied emf of 4.50 V?

Question

Quizplus · Accepted Answer

To solve this problem, we need to use the equation:
energy = voltage x charge

We can find the charge by using the equation:
moles of electrons = moles of magnesium
moles of electrons = mass of magnesium / molar mass of magnesium * 2 (because Mg2+ gains two electrons)
moles of electrons = 3.00 kg / 24.31 g/mol * 2 = 0.246 mol of electrons

Charge = moles of electrons x Faraday's constant
Charge = 0.246 mol x 96,485 C/mol = 2.37 x 10^4 C

Now we can find the energy by plugging in the values:
energy = 4.50 V x 2.37 x 10^4 C
energy = 1.0665 x 10^5 J

To convert to kilowatt-hours, we need to divide by 3.6 x 10^6 J/kWh:
energy = 1.0665 x 10^5 J / 3.6 x 10^6 J/kWh
energy = 0.0296 kWh

Therefore, the answer is D) 29.8.

How Many Kilowatt-Hours of Electricity Are Used to Produce 3