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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: joyb on February 28, 2013, 09:52:55 AM

Title: How do I graphically determine number of electrons involved using Nernst?
Post by: joyb on February 28, 2013, 09:52:55 AM
Here is a link to the full question:
http://sphotos-g.ak.fbcdn.net/hphotos-ak-ash3/75511_10200234689223393_1257554636_n.jpg

First, I'd just like to check... to convert the standard electrode potential from normal to biochemical, do you in this case add RT/nF ln(10-14) to the normal Eo? If not, how do you convert between them?

The main part I'm stuck on is question e). What data am I plotting?
Title: Re: How do I graphically determine number of electrons involved using Nernst?
Post by: Borek on February 28, 2013, 10:13:57 AM
Quote from: amberbarton on February 28, 2013, 09:52:55 AM
to convert the standard electrode potential from normal to biochemical, do you in this case add RT/nF ln(10-14) to the normal Eo?

That's more or less my understanding - you just convert to pH 7 from the standard state (which assumes 1M - or more precisely, activity of 1).

Quote
The main part I'm stuck on is question e). What data am I plotting?

Good question. I suppose it was explained during a lecture or in the book, as the question itself doesn't say anything. I have a gut feeling you are expected to use the slope to determine number of electrons, but other than that, I have no idea what you should do.
Title: Re: How do I graphically determine number of electrons involved using Nernst?
Post by: joyb on February 28, 2013, 10:18:27 AM
No, it was not explained. I've just written out how I would work it out if I had different data.
Title: Re: How do I graphically determine number of electrons involved using Nernst?
Post by: joyb on February 28, 2013, 10:22:47 AM
Except I'm now confused as to how I would do it.
Title: Re: How do I graphically determine number of electrons involved using Nernst?
Post by: Borek on February 28, 2013, 10:26:59 AM
How you would do what?

There were two questions of which one you approached correctly (unless you got the sign wrong, it is always possible and I admit I have not checked), other we both have no idea how to approach.