Write two balanced half reactions for the titration of iodin

Write two balanced half reactions for the titration of iodine with sodium thiosulfate. Indicate what is being oxidized and what is being reduced. Show the equivalent wt. of I2 = 126.9.

I2   +   2 Na2S2O3 ----->   2 NaI   +   Na2S2O6

The above reaction is not the answer. I\'m not sure what two half reactions are. Also, what is oxidized and what is reduced? and Finally, how can I show the equivalent wt. of I2 = 126.9. Complete answer plz.

Solution

I2 + 2e- ---->2I-

2S2O3 2- ----> S4O6 2- +2e-

SO,

I2 + 2Na2S2O3 --->Na2S4O6+ 2NaI

EQUIVALENT Weight if I2=127/2

=63.5

reduced= I2 (since it gains electrons)

oxidised= S2O3 2- (since it loses electrons)