# To an aqueous solution of Na2SO3 added 25 ml of 0.1n of I2 solution.4 ml of 0.09 n Na2S2O3 solution was used for the titration of excess I.Find the mass of Na2SO3

Answer from: **Milena Egorova:***1,7 K...*

I2+2Na2S2O3=2NaI+Na2S4O6

Cn1V1=Cn2V2

Cn(I2)=(C(Na2S2O3)*V(Na2S2O3)):(V(I2))=(10,25*0,1):10=1,025:10=0,1025.

The mass is 0.1025

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