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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: CoronadoA3 on May 04, 2009, 11:37:10 PM

Title: Electrochemistry
Post by: CoronadoA3 on May 04, 2009, 11:37:10 PM

I recently did an online problem and requested for the answer. I wanted to know if Delta G and Delta G reaction are the same thing. When I used Delta G = -nFE


According to formula for Delta G = -nFE cell. Where n is in mols, F is Faradays (96485) and E cell for problem given in picture is 1.33 V. I assumed that n= 6.
 
When the equation was balanced I got:
 
6e- +14 H+ +Cr2O7^2- --> 2Cr^3+ +7H2O
 
Balancing out anything with:
H20 use O atoms
H+ to balance H atoms and
e- to balance positive charges.
 
I want to know if I used the wrong equation to find Delta G rxn. My answer was  -769950.3 kj and the requested answer was 1060 kJ, why?

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi41.tinypic.com%2F2qk5r3l.jpg&hash=1359e6d4bec824910269dbb3da00a211df0e4d37)

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi44.tinypic.com%2F1ypyxk.jpg&hash=4f2c13f31235eaa66b3266f4eb3eb104013e8f0a)

Title: Re: Electrochemistry
Post by: Rabn on May 06, 2009, 01:56:58 AM

I have a really quick question for you: If you're trying to solve for  :delta: G^o, why aren't you using an equation where :delta: G^o is a variable?