chem question electrolysis

13

hi, please could I have some help on this question? I did 1.23-(-0.02) to get 1.25 but the ms Eocell = 1.23 – 0.02 = 1.21 V?
Question ii on page 20: https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FPast-Papers%2FCAIE%2FPaper-4%2FQP%2FNovember%202018%20(v1)%20QP.pdf
thanks!

Reply 1

Kallisto

Entertainment Forum Helper, Life & Style Forum Helper

22

If I know the materials of the electrodes, I am certainly able to calculate it, but with nothing more but a given value? no clue.

@TypicalNerd
@Pigster

You two are more up to date than me, you can help for sure.

Reply 2

anonymous56754

OP

13

Original post

by Kallisto

If I know the materials of the electrodes, I am certainly able to calculate it, but with nothing more but a given value? no clue.
@TypicalNerd
@Pigster
You two are more up to date than me, you can help for sure.

sorry, here is the data booklet: pages 7 to 8
https://www.cambridgeinternational.org/images/164870-2016-specimen-data-booklet.pdf

Reply 3

TypicalNerd

18

Original post

by anonymous56754

hi, please could I have some help on this question? I did 1.23-(-0.02) to get 1.25 but the ms Eocell = 1.23 – 0.02 = 1.21 V?
Question ii on page 20: https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FPast-Papers%2FCAIE%2FPaper-4%2FQP%2FNovember%202018%20(v1)%20QP.pdf
thanks!

It’s because CIE are sneaky little buggers and swapped the equation around.

Normally electrode potentials are given to show reduction potentials - the given equation in the question is reversed to show oxidation. Essentially, it’s already the negative of the reduction potential, so you just add it on to the relevant reduction potential from the data booklet.

chem question electrolysis

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