A2.2 Electrolysis Calculations
These always involve using the equation
Note:
I is the current in amps,
t is the time in seconds,
Q is the number of coulombs of electrical charge that have passed through the electrolytic cell. This charge can be related to the charge on one mole of electrons.
1 mole of electrons has a charge of 96,500 coulombs = 1 Faraday
so
You will need to take into account how many F of charge is needed to deposit 1 mole of the substance in question. So you will need the following electrode equation:
e.g.
or
so 1 mole of Ca needs 2 F but 1 mole of Al needs 3F
Follow this scheme to answer the question: | |
1. Calculate Q
Q = I x t | |
2. Calculate the number of moles of electrons passed (Faradays)
F = Q / 96500 | |
3. Consider the equation | |
4. So no. of moles of substance formed = moles of substance / no of moles of e in the equation. | |
5. Mass of product = no of moles Molar mass | |
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