Help with chemistry :(?

Question

if aluminium oxide is electrolyse for 10 minutes at 10V and 8000 A, the total energy consumed is?

[aluminium oxide is dissolved in molten cryolite at 1000'C,

Al2+ +3e- = Al (E'V= -1.66]

Answer 1

A volt is a joule/coulomb

An ampere is coulomb/second

If we multiply (voltage x current x time) we should get the energy in joules.

joule/coul x coul/sec x sec = joules

10V x 8000 amps x (10 min x 60s/min) = 48,000,000 J

or 48 megajoules

(Assuming we managed to have enough precision to get two significant digits.)

This is why it is so important to recycle aluminum.  The refining of bauxite to make aluminum is a very energy intensive process.

Answer 2

I would not know of a method a chemist would use to solve this, but I would know how a physicist would do it.

Simply use the power equation P = iV where i is the current and V is the voltage.

P = 8000 A * 10 V = 8 * 10^4 W

By definition, P = E/t where E is the energy transferred and t is the time that has elapsed. Thus, E = Pt.

E = (8 * 10^4 W)(10 min) * 60 seconds / 1 minute

E = 4.8 * 10^7 J

I didn't pay much attention to sig figs, but if I did, then E = 5 * 10^7 J