When to use standard potentials and when to balance

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Lucia H 2L
Posts: 43
Joined: Mon Nov 14, 2016 3:00 am
Been upvoted: 1 time

When to use standard potentials and when to balance

Postby Lucia H 2L » Thu Mar 15, 2018 9:00 pm

What is the difference was between skeletal reactions that you have to balance by adding H+ and OH- vs skeletal reactions that you can jut copy down from the standard potentials page? In theory, a half reaction is a half reaction, right?

Tanaisha Italia 1B
Posts: 55
Joined: Fri Sep 29, 2017 7:04 am

Re: When to use standard potentials and when to balance

Postby Tanaisha Italia 1B » Fri Mar 16, 2018 12:00 am

I think that if the products have oxygen or hydrogens that are unaccounted for in the reactants then you would have to balance by adding H+ and OH-. Especially when it says something along the lines of:
1. Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in acidic solution.
or
2. Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in basic solution.

If the reaction is something simple, like Mg2- + 2e- -----> Mg, you don't need to add anything because there are no oxygens or hydrogens on either side.
If it is more complicated, and one side has an oxygen/hydrogen and the other does not, you have to add it:
Ex. 2ClO3- + 5e- -----> Cl2
You would have to balance this because 2ClO3- has 6 oxygens which have to be accounted for on the other side (by adding 6H20, the oxygen has to go somewhere)

Kaileigh Yang 2I
Posts: 49
Joined: Sat Jul 22, 2017 3:00 am

Re: When to use standard potentials and when to balance

Postby Kaileigh Yang 2I » Fri Mar 16, 2018 11:02 am

It's just like balancing an equation to complete it. Just remember to balance according to whether it is a basic or acidic solution.


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