Balancing redox reactions.Need help!?

a) a solution of sodium oxalate, Na2C2O4 was titrated by 30 ml of .02 M potassium permanganate in acidic solution. Balance the redox reaction: C2O4-2 + MnO4- -----> CO2 + Mn 2+ and determine the mass of sodium oxalate in the unknown sample. b)A solution of sodium thisosulfate Na2s2O3, can be titrated... show more a) a solution of sodium oxalate, Na2C2O4 was titrated by 30 ml of .02 M potassium permanganate in acidic solution. Balance the redox reaction: C2O4-2 + MnO4- -----> CO2 + Mn 2+
and determine the mass of sodium oxalate in the unknown sample.

b)A solution of sodium thisosulfate Na2s2O3, can be titrated using a solution of iodine:
S2O3-2 + I2 -----> I- + S4O6-2

Balance the above redox equation and find the molarity of an unknown sodium thiosulfate solution, if 35mL of a .02 M iodine solution was used to titrate a 45.0 mL sample of sodium thisosulfate.

Please help. I have no idea where to start! I have an idea, but I'm afraid if I do some of the starting steps wrong I won't get any of it.
Update: That's not all of my question. I'm not even sure what part that is..? I'm even more confused now I think
Update 2: For the first problem I wasn't given to volumes though. I reviewed what I typed and there isn't anything I can find missing from what I was given. I don't know how to determine it from there. Really the balancing the redox reactions part is what really getting me confused. If I can figure out the... show more For the first problem I wasn't given to volumes though. I reviewed what I typed and there isn't anything I can find missing from what I was given. I don't know how to determine it from there. Really the balancing the redox reactions part is what really getting me confused. If I can figure out the reaction, I think I can get the rest. I was under the impression that I was suppose to add h2o to balance a redox reaction when it is titrated.
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