Electrolysis

*First Law

The quantity of a substance produced by electrolysis is proprotional to the quantity of electricty used.

*Second Law

For a given quantity of electricity the quantity of substance produced is proportional to its weight.

*The quantity of electricity or charge contained in a current running for a specified time can be calculated: Q = I x t

Q = quantity of electricity or charge in coulombs (C)

I = current in amps (A)

t = time (seconds)

*The Faraday constant, F, is the quantity of electricity carried by one mole of electrons.

F = Avogadro's Number x charge on electron in coulombs

F = 6.022 x 1023 mol-1 x 1.602192 x 10-19 C

F = 96,484 C mol-1

This is usually rounded off to 96,500 C mol-1 for calculations in chemistry.

*The quantity of electricity required to deposit an amount of metal can be calculated: Q = n(e) x F

Q = quantity of electricity in coulombs (C)

n(e) = moles of electrons

F = Faraday constant = 96, 500 C mol-1

*Electrical Energy, E, can be calculated: E = Q x V

E = electrical energy in joules (J)

Q = quantity of electricity in coulombs (C)

V = voltage (or EMF) in volts (V)

*1 kilowatt-hour, kWH, is a unit of electrical energy.

1 kWH = 3.6 x 106 J

Examples

*Q = I x t

Calculate the quantity of electricity, Q, obtained when a current of 25 amps runs for 1 minute.

Q = ? C

I = 25 A

t = 1 minute = 60 seconds

Q = 25 x 60 = 1,500 C

Calculate the current needed to 30,000 coulombs of electricity in 5 minutes.

Q = 30,000 C

I = ? A

t = 5 minutes = 5 x...

## Very helpful

Thanks a lot for this one, worked examples were very helpful for me.

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