Calculating K

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Felicia Fong 2G
Posts: 31
Joined: Sat Jul 22, 2017 3:00 am

Calculating K

Postby Felicia Fong 2G » Wed Feb 21, 2018 12:18 pm

The practice midterm test questions involve calculating K. However, a variety of formulas were used in the solutions. ∆G° = - RT ln K ,
Ecell=(RT/nF) ln K and E=Ecell-.05916V/n * logQ. Does it matter which formula we use?

Posts: 58
Joined: Fri Sep 29, 2017 7:04 am

Re: Calculating K

Postby rkusampudi » Wed Feb 21, 2018 12:26 pm

Of the equations you listed, only the first two equations allow for you to calculate K, the last equation is Q which is the reaction quotient not the equilibrium constant.

Lauren Seidl 1D
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

Re: Calculating K

Postby Lauren Seidl 1D » Wed Feb 21, 2018 12:50 pm

You can use either of the first two equations, depending on what values are given. If given deltaG directly, then the first equation is easier to use. If only given standard cell potential, then the second equation is easier to use. The third can be used when the reaction is not in equilibrium.

William Xu Dis 1D
Posts: 31
Joined: Fri Sep 29, 2017 7:05 am

Re: Calculating K

Postby William Xu Dis 1D » Wed Feb 21, 2018 1:56 pm

Either of the first two equations can be used. Just be sure to choose the one that is simplest used based off of the variables provided. For galvanic cells, the equation involving cell potential will likely be the best equation to use.

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