Finding Q

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Justin Chu 1G
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Joined: Thu Jul 13, 2017 2:00 am
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Finding Q

Postby Justin Chu 1G » Wed Feb 21, 2018 10:36 pm

When would you know to use the lnQ or logQ equations when finding cell potential? For example, the problem 14.47, I used the equation for lnQ and got lnQ=15, but the answer says 10^6, which would only be possible if using the logQ equation.

Thu Uyen Tran 1B
Posts: 31
Joined: Fri Sep 29, 2017 6:05 am

Re: Finding Q

Postby Thu Uyen Tran 1B » Wed Feb 21, 2018 11:54 pm

I'm also confused with this one. When I exponentiated both sides to solve for Q, my answer was 3.27x106. Why does it only show 106 as the answer?

Posts: 32
Joined: Sat Jul 22, 2017 2:00 am

Re: Finding Q

Postby torieoishi1A » Thu Feb 22, 2018 2:55 pm

Using the Nernst equation with Ln and log should be interchangeable, but I had this same issue with this problem. I also got 3.27x10^6 rather than just 10^6.
There is an added constant for log. For ln: E = E-RT/nF(lnQ) but for log: E = E-2.303RT

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