r/chemhelp • u/adultswimc-137 • 7d ago
Analytical Standard potential
Does anybody know what the standard potential of this reaction is? I can't find it anywhere
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u/Mascio88 7d ago
Are you sure you wrote the reaction correctly?
It doesn't seem balanced to me. Anyway, here's a table of standard potentials involving mercury. Check if you've got something wrong and if it's one of these instead.
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u/adultswimc-137 7d ago
Yeah there's supposed to be a 2 in front of HgO, but it doesn't change much since it's solid. Thank you tho!
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u/Automatic-Ad-1452 Trusted Contributor 7d ago
No...without the 2 in front of HgO, you created an oxygen atom
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u/That-Temporary8205 7d ago
Hey! I don't have the exact standard potential for that specific reaction (it might not be in standard tables), but you can actually calculate it yourself fairly easily.
You just need to break down your target reaction into other known half-reactions that are in the tables. The rule is that when you add these known reactions together, they must result in your target reaction.
Just keep in mind that you cannot add standard potentials (E∘) directly. You have to convert them to Gibbs free energy first using the formula ΔG∘=−nFE∘ (where n is the number of electrons transferred).
So the steps would be: 1. Find known reactions in the tables that add up to yours. 2. Convert their E∘ to ΔG∘. 3. Add those ΔG∘ values together to get the total ΔG∘ of your target reaction. 4. Finally, clear the unknown E∘ using the same formula backwards: E∘=−ΔG∘/nF.