Tuesday, 30 April 2013

1.57 calculate the amounts of the products of the electrolysis of molten salts and aqueous solutions

One faraday is 96500 coulombs. It is also one mole of electrons.

If current of 0.2 Apms is passed through copper(ll) sulphate for tow hours, how much copper do you get?


  • Write out the half equation
Cu2+ + 2e > Cu
  • Work out coulombs of electrons flowing
Coulombs= current x time
Q= IT
time is 2x60x60 (times 60 makes minutes, times 60 again makes it seconds)
Q= 0.2 x 7200= 1440 coulombs
  • Convert C into moles of electrons
Moles= C/Faraday
Mol= 1440/96500
Mol= 0.015
  • Work out scale factor
Cu2+ + 2e > Cu
For every 2 moles of electrons, there will be one Cu
Sf= Moles of product/ moles of electrons
Sf= 1/2
Sf= a half
  • Work out moles of product using Scale factor
so we do the moles of electrons times the scale factor
0.015x1/2= 0.0075 Moles of Cu
  • Convert moles into mass
Moles x Mr
0.0075 x 63.5= 0.48g of copper

17 comments:

  1. Thanks for the help, always found these ones difficult!

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  2. Your speeling is appaaling as you cannot spell "two"

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    Replies
    1. My spelling is really bad, but to be fair to me the 'tow' was probably a typo haha

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  3. Shut up Marco Polo u carnt spel eithar

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  6. Hi, How do you account for the concentration of the electrolyte?

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  7. Hi is the scale factor the same as the stoich?

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  8. Thanks for the help! but I think for igcse they say that 1 faraday is 96000 coulombs, not 96500

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    1. They actually don't! All the past papers I've ever come across they've told you it's 96500 x

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