14.3 Balancing redox reactions

[Vanessa Romero-Campos 2B]

a)Cl2 + S2O3(-2) --->Cl (-1) + SO4 (-2)

I am trying to balance the reaction and so far I have Cl2+2e-->2Cl- and S2O3(-2)+5H2O---> 2SO4 (-2) + 10H+
How do I finish balancing: S2O3(-2) + 5H2O---> 2SO4 (-2) + 10H+

[Abigail Yap 2K]

The last step is to balance the charges. You currently have a charge of -2 on the left side of the reaction, and a charge of 2(-2) + 10 = +6 on the right side of the reaction. Adding 8 electrons to the products side will balance the charges.

Your final balanced reaction will be:
S2O3(2-) + 5H2O -> 2SO4(2-) + 10H+ + 8e-

[Juanyi Tan 2K]

I agree with Abigail! The two things we should look for when we balance the redox equation are the charge and the number of elements.