Determining n in nernst equation


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Katie Clark 3B
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Joined: Fri Sep 25, 2015 3:00 am

Determining n in nernst equation

Postby Katie Clark 3B » Fri Mar 11, 2016 8:09 pm

How do you determine what n is in the Nernst equation? For example, if you had the equation 2Cr3+ + 3HClO2 + 4H20 -> CrO72- + 3HClO + 8H+ , how would you determine what to use for n in the equation E= Estandard - (.05916V)/n logQ

Franca Park 3J
Posts: 64
Joined: Fri Sep 25, 2015 3:00 am

Re: Determining n in nernst equation

Postby Franca Park 3J » Fri Mar 11, 2016 9:14 pm

n is the number of moles of electrons that you "cross" out.
so for that reaction you would have to split it into the two half reactions, balance it (balance the elements first, then add H2O to balance the oxygens, then add H+ to balance the hydrogens, then add electrons to balance the charge), and write the overall net reaction by adding the two half reactions. whatever number of electrons you crossed out when adding up the two half reactions is n


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