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Standard Electrode Potentials

park1996

Hi everyone,
I don't understand this answer - it is for the disproportionation of Cu+ to Cu and Cu2+...

I thought that the equation for Ecell was Ereduced - Eoxidised. Once the value of the Cu2+ to Cu+ is reversed from +0.15 to -0.15, in order to show in the disproportionation that it is being oxidised, the numerical equation should be shows +0.52 - 0.15 = +0.37V.... I thought it would be +0.52 - (-0.15) = +0.67V

Please help...

Thanks for all those answer :smile:

(edited 8 years ago)

Reply 1

frozo123

Original post by park1996

Hi everyone,
I don't understand this answer from the mark scheme - it is for the disproportionation of Cu+ to Cu and Cu2+...

I thought that the equation for Ecell was Ereduced - Eoxidised. But, in the mark scheme, once the value of the Cu2+ to Cu+ is reversed from +0.15 to -0.15, in order to show in the disproportionation that it is being oxidised, the numerical equation should be +0.52 - (-0.15) = +0.67V ...NOT as it shows +0.52 - 0.15 = +0.37V

PLEASE HELP...I thought I understood this!?

Thanks for all those answer :smile:

No that's right
And no the mark scheme doesn't say that, go to sleep

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Reply 2

park1996

Original post by frozo123

No that's right
And no the mark scheme doesn't say that, go to sleep

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Why don't you?

(edited 8 years ago)

Reply 3

park1996

Please could anyone help?

Do you ever reverse the sign?

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Reply 4

frozo123

Original post by park1996

Please could anyone help?

Do you ever reverse the sign?

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You do reverse the sign if you reverse the equation yes
So if you wrote as oxidation it would be -0.15 :smile:

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Reply 5

frozo123

Original post by park1996

Please could anyone help?

Do you ever reverse the sign?

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If you reverse the equation, you reverse the sign :smile:

What you did is right however

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Reply 6

park1996

But then the correct equation would be 0.52 - (-0.15) wouldn't it?

Not as the pic says?

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Reply 7

frozo123

Original post by park1996

But then the correct equation would be 0.52 - (-0.15) wouldn't it?

Not as the pic says?

Posted from TSR Mobile

No because if you reverse it you add them together not subtract them

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Reply 8

park1996

Original post by frozo123

No because if you reverse it you add them together not subtract them

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Ah, thanks a lot mate! :smile:

Reply 9

frozo123

Original post by park1996

Ah, thanks a lot mate! :smile:

just stick with what you said reduced - oxidised
write the equation how it is
look what's getting reduced, looks what's getting oxidised
subtract
so 0.52- 0.15=0.37
:smile:

what grade did you get last year?

Reply 10

park1996

Original post by frozo123

just stick with what you said reduced - oxidised
write the equation how it is
look what's getting reduced, looks what's getting oxidised
subtract
so 0.52- 0.15=0.37
:smile:

what grade did you get last year?

A..why?

Reply 11

frozo123