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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: tg22542 on August 11, 2013, 02:02:02 PM

Title: Quick Electrode Potential Question - Need help asap
Post by: tg22542 on August 11, 2013, 02:02:02 PM

I'm looking at a problem which states:

calculate the  E°cell:

3 Ag+(aq) + 3 e− → 3 Ag(s)    E° = 0.80 V 

Fe3+(aq) + 3 e− → 3 Fe(s)     E° = −0.04 V

This could be a dumb question, but where is the Ecell value of -.04V coming from? I know where the 0.8 is coming from but I can't seem to figure out the second value. Any tips/ideas?

Title: Re: Quick Electrode Potential Question - Need help asap
Post by: magician4 on August 11, 2013, 03:38:29 PM

Quote

but where is the Ecell value of -.04V coming from?

this is a well-known standard value for named process

see for example:
http://en.wikipedia.org/wiki/Standard_electrode_potential_%28data_page%29

regards

Ingo

Title: Re: Quick Electrode Potential Question - Need help asap
Post by: rosa on August 14, 2013, 07:35:40 AM

Hi,
Is it the negative sign before the value causing problem? The full cell will undergo a redox reaction but both the half cell equations given show only reduction processes You may have to identify which half cell endergoes oxidation process