How to balance half reaction

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marcus lin 1E
Posts: 54
Joined: Fri Sep 28, 2018 12:28 am

How to balance half reaction

Postby marcus lin 1E » Sun Mar 17, 2019 9:10 am

How do we use OH- to balance out half reactions in alkaline solutions?

Matthew Tran 1H
Posts: 165
Joined: Fri Sep 28, 2018 12:16 am

Re: How to balance half reaction

Postby Matthew Tran 1H » Sun Mar 17, 2019 9:19 am

The way I like to do it is to balance the reaction the same way I would if it were acidic, then adding OH- to both sides to neutralize the H+. When you do that, H+ and OH- combine to make H2O, so you've essentially only added H2O and OH-.

Briana Lopez 4K
Posts: 44
Joined: Wed Nov 22, 2017 3:01 am

Re: How to balance half reaction

Postby Briana Lopez 4K » Sun Mar 17, 2019 9:20 am

In an alkaline solution OH- is used to balance the number of oxygen and hydrogen atoms on both sides. Then electrons are used to balance the charge

Henry_Phan_4L
Posts: 68
Joined: Fri Sep 28, 2018 12:24 am

Re: How to balance half reaction

Postby Henry_Phan_4L » Sun Mar 17, 2019 9:40 am

You can add H2O to the side that needs more oxygens, then add double OH- along with it and add double the H2O to the other side.

Jonathan Omens 1K
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Re: How to balance half reaction

Postby Jonathan Omens 1K » Sun Mar 17, 2019 5:45 pm

I agree with Henry's answer except instead of adding OH- equal to double the amount of H2O initially added, find how many H one side needs to make it balanced and and add twice that amount of H2O to that side and that amount of OH- to the other side.
Also don't forget to balance all the other reactants and products before you get to this step.

Anita Wong 1H
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Joined: Fri Sep 28, 2018 12:27 am
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Re: How to balance half reaction

Postby Anita Wong 1H » Sun Mar 17, 2019 5:53 pm

what i do is add the h2o to balance out the Os, then add H to balance H, then for the amount of H you add, add the same amount of OH to each side. The oh and h should combine to form h2o with can be added to/subtracted. just simplify from there!


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