Q for Nernst Equation


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Mike Vinci 2B
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Q for Nernst Equation

Postby Mike Vinci 2B » Tue Feb 20, 2018 10:22 am

In the Nernst equaiton, why do we only use the ratios of the concentrations of aqueous products and not solid or liquids? Also, would we include gases in the ratio, as well? I recall seeing Q include aqueous concentrations by atms/bars, so I am guessing that gases are included? If someone could clarify it'd be helpful.

Cassandra Mullen 1E
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Re: Q for Nernst Equation

Postby Cassandra Mullen 1E » Tue Feb 20, 2018 10:33 am

Remember when writing equilibrium constant expressions, the concentrations of solids and liquids are excluded, since they essentially have constant concentration throughout the reaction. For cell potential, we are concerned with the voltage related to the concentration of aqueous solutions, since that is the medium we're working with. I'm not too sure about examples using gases (since the aqueous solution is what allows for the ion transfer), but the gas constant R is accounted for in the Nernst equation.


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