adding correct charge

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Delaney Smith 1C
Posts: 52
Joined: Thu Feb 28, 2019 12:15 am

adding correct charge

Postby Delaney Smith 1C » Tue Mar 03, 2020 4:57 pm

Hi! For some problems such as 6K.5, when I am adding the electrons to balance the charge, I am sometimes getting the wrong number of electrons. I know how to find the initial and final oxidation numbers, but why isn't the charge you add to the reactants or products always equal to the change in oxidation number?

Deena Doan 2F
Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

Re: adding correct charge

Postby Deena Doan 2F » Tue Mar 03, 2020 5:22 pm

I think it's because you have to look at the net charge of the overall molecule instead of the charges of the components of the molecule.

Posts: 50
Joined: Mon Nov 11, 2019 12:17 am

Re: adding correct charge

Postby 205291012 » Tue Mar 03, 2020 10:55 pm

Adding electrons should be the last step after you have balanced all the elements, H, O. Then look at net charge on both sides and you can add the electrons accordingly.

Max Madrzyk Dis 4G
Posts: 102
Joined: Wed Sep 18, 2019 12:21 am

Re: adding correct charge

Postby Max Madrzyk Dis 4G » Tue Mar 03, 2020 11:25 pm

Make sure you have all of your elements balanced and then make sure you multiply any molecules with a charge by their coefficient and then you should be able to get the right number of electrons.

Posts: 60
Joined: Wed Sep 21, 2016 2:56 pm

Re: adding correct charge

Postby Uisa_Manumaleuna_3E » Wed Mar 04, 2020 1:18 pm

try to remember the order in which we balance everything:
1. balance all the elements (that aren't Oxygen or Hydrogen)
2. add H20 to balance oxygen
3. add H+ to balance the Hydrogens
5. scale the reactions so electrons cancel out

like it was said before you have to make sure that the electrons are the last thing you try to balance, because (as you can see above) the other elements, O and H have to already be set and balanced so you can make the accurate comparisons of charges necessary. Once you do that you should be fine.

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