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half reaction

Posted: Sun Feb 23, 2020 11:43 pm
by nshahwan 1L
how do you know when to put water in the half reaction when balancing?

Re: half reaction

Posted: Sun Feb 23, 2020 11:45 pm
by Petrina Kan 2I
I am confused about the same thing. In my discussion, my TA included water in the acidic redox reaction (with H2O and H3O+) but not the basic one (she only included OH- with no H2O). I am confused as to why.

Re: half reaction

Posted: Sun Feb 23, 2020 11:47 pm
by andrewcj 2C
In acidic solution, you add water to balance out the oxygen in the half reaction.
In basic solution, you do the same as above but you also add OH- to the side with H+ in order to neutralize the acidity of that side, which makes water.

Re: half reaction

Posted: Mon Feb 24, 2020 12:26 am
by Aiden Metzner 2C
You include water in the half reaction when you need to balance O2 in the reaction. Then if there are left over H+ ions you include water in the reaction as well as OH- ions

Re: half reaction

Posted: Mon Feb 24, 2020 2:38 pm
by CosetteBackus_4F
Balance oxygen with water and balance hydrogen with H+ in acidic solutions.

Re: half reaction

Posted: Mon Feb 24, 2020 2:42 pm
by Abhi Vempati 2H
Pages 538-543 in the textbook were really helpful for me, and it explains each step clearly and gives examples to follow along with. Hope this helps!

Re: half reaction

Posted: Mon Feb 24, 2020 3:00 pm
by charleejohnson1L
it really helped me when my TA like, explicitly stated that you can only add what's already in the solution. so like if it says it's an acidic solution, the only thing in there except for the redox reaction is water and hydrogen ions, and if it says it's a basic solution, the only thing in there except for the redox reaction is water and hydroxide ions. you just keep adding either or until your redox half reactions are balanced, and then when you add your half reactions, you'll get the full reaction! I hope this helps :)

Re: half reaction

Posted: Mon Feb 24, 2020 5:06 pm
by Sam McNeill 1E
For balancing half reactions in acidic conditions, use 1) Balance everything other than H and O 2)Balance O using H2O 3)Balance H using H+ 4)Balance charges by adding electrons 5)Add the half reactions together. For basic conditions, follow the same steps but at the end cancel out H+ by adding OH- to both sides and turning the H+ and OH- into water.

Re: half reaction

Posted: Tue Feb 25, 2020 2:43 pm
by ABombino_2J
Use H2O to balance the Oxygen in the reaction and then use H+ to balance the Hydrogen as a result of adding H2O. Then balance the charges by adding e-. Multiply the half reactions so that the charges cancel each other out then add the reactions together. If it is a basic solution add OH- to both sides to make water from the reaction H++OH-=H20

Re: half reaction

Posted: Sun Mar 01, 2020 10:13 pm
by nshahwan 1L
thank you so much for all the great explanations!!

Re: half reaction

Posted: Sun Mar 01, 2020 10:19 pm
by J_CHEN 4I
In acidic solutions, balance the half equation with H+ and H20. For basic solutions, balance the half reaction with OH- and H20. For some cases, like the reaction (H+) + (OH-) -> H20, you might need to look for the reduction/oxidation potentials given in the book.