Number of electrons

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Brandon Mo 4K
Posts: 70
Joined: Fri Sep 28, 2018 12:15 am

Number of electrons

Postby Brandon Mo 4K » Fri Feb 22, 2019 1:16 am

How do we determine the number of electrons in the oxidation and reduction half-reactions?

Kevin ODonnell 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

Re: Number of electrons

Postby Kevin ODonnell 2B » Fri Feb 22, 2019 4:26 am

In half reactions we just find the sum of the two halves (the reduction half-reaction + the oxidation half-reaction). First make sure all of the equations are balanced. Make sure in molecule compounds as well that you are taking note of the sign. For example, let's pretend that FeO2-2 is a thing. We know O has a charge of -2 and -2 * 2 atoms = -4 charge, so we can deduce Fe has a initial charge of +2, and if it is oxidized we will see that it has a +3 charge on the product side.
As far as half reactions go I will attach an easy example:
Attachments
Screen Shot 2019-02-22 at 4.26.14 AM.png

Bruce Chen 2H
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

Re: Number of electrons

Postby Bruce Chen 2H » Fri Feb 22, 2019 2:31 pm

We want to balance the number of electrons on both sides. In order to do this, we must add electrons in the half reactions. They should cancel out when added.

204929947
Posts: 76
Joined: Fri Apr 06, 2018 11:03 am

Re: Number of electrons

Postby 204929947 » Fri Feb 22, 2019 3:34 pm

In adittion, how would you find out the oxidation number of an element??

Celine Cheng 1H
Posts: 33
Joined: Fri Sep 28, 2018 12:21 am
Been upvoted: 1 time

Re: Number of electrons

Postby Celine Cheng 1H » Fri Feb 22, 2019 3:57 pm

For the oxidation numbers question, you generally want to look at the charge of the element/compound. The sum of the oxidation numbers of the elements in a compound should equate to the compound's overall charge. There are some specific rules for finding oxidation numbers of certain elements, which you can find here: https://www.khanacademy.org/science/che ... ion-number

Jocelyne Milke 1G
Posts: 73
Joined: Fri Sep 28, 2018 12:25 am

Re: Number of electrons

Postby Jocelyne Milke 1G » Fri Feb 22, 2019 5:14 pm

you can find the oxidation numbers using the periodic table


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