Balancing Redox in Acids and Bases
Moderators: Chem_Mod, Chem_Admin
Balancing Redox in Acids and Bases
How would I know to balance an equation the acid way or the base way if they don't specify in the question. For example, 14.15 part C says: Cd+2Ni (OH)3---> Cd (OH)2....Do I use the method for bases because there is an OH involved?
-
Daniella Ching 4C
- Posts: 20
- Joined: Fri Sep 25, 2015 3:00 am
Re: Balancing Redox in Acids and Bases
Since they give you the entire reaction, Cd(s) + 2 Ni(OH)3(s) -> Cd(OH)2(s) + 2 Ni(OH)2(s)
you can balance the half reactions by first separating Cd and Ni into separate reactions.
The first one would be: Cd(s) -> Cd(OH)2(s)
and Ni would be: 2 Ni(OH)3(s) -> 2 Ni(OH)2(s)
Then you can add OH- accordingly to balance out the reaction. Therefore, the Cd half reaction would be:
2OH- + Cd(s) -> Cd(OH)2(s)
and the Ni half reaction would be:
2 Ni(OH)3(s) -> 2 Ni(OH)2(s) + 2OH-
(If the two sides were unbalanced by just missing hydrogen, then you would just add H+ to balance it. Since its missing both oxygen and hydrogen, then you add OH-).
Then you can balance the electrons for both half reactions, since now the sides with OH- has a -2 charge (so the other sides---products for Cd and reactants for Ni---have 2 electrons added to them to make it an overall neutral charge for the half reaction).
By approaching the problem like this, you don't need to memorize an acid way or a base way (you would just add H+ or OH- accordingly after seeing what makes the half reaction unbalanced). Hopefully this helps!
you can balance the half reactions by first separating Cd and Ni into separate reactions.
The first one would be: Cd(s) -> Cd(OH)2(s)
and Ni would be: 2 Ni(OH)3(s) -> 2 Ni(OH)2(s)
Then you can add OH- accordingly to balance out the reaction. Therefore, the Cd half reaction would be:
2OH- + Cd(s) -> Cd(OH)2(s)
and the Ni half reaction would be:
2 Ni(OH)3(s) -> 2 Ni(OH)2(s) + 2OH-
(If the two sides were unbalanced by just missing hydrogen, then you would just add H+ to balance it. Since its missing both oxygen and hydrogen, then you add OH-).
Then you can balance the electrons for both half reactions, since now the sides with OH- has a -2 charge (so the other sides---products for Cd and reactants for Ni---have 2 electrons added to them to make it an overall neutral charge for the half reaction).
By approaching the problem like this, you don't need to memorize an acid way or a base way (you would just add H+ or OH- accordingly after seeing what makes the half reaction unbalanced). Hopefully this helps!
Return to “Balancing Redox Reactions”
Who is online
Users browsing this forum: No registered users and 11 guests