The reduction of peroxydisulphate ion by `I^(-)` ion is expressed by `S_(2)O_(8)^(2-) + 3 I^(-) rarr 2SO_(4)^(2-) + I_(3)^(-)` ,If rate of disappearance of `I^(-)` is `9//2xx10^(-3)` mol `L^(-1) S^(-1)`, what is the rate of formation of `SO_(4)^(2-)` during same time ?

Options

A. `10^(-3) "mol"//L^(-1)s^(-1)`
B. `2 xx 10^(-3) "mol"//L^(-1)s^(-1)`
C. `3 xx 10^(-3) "mol"//L^(-1)s^(-1)`
D. `4 xx 10^(-3) "mol"//L^(-1)s^(-1)`

Answer

C

Explanation

`(1)/(2)(d[SO_(4)^(2-)])/(d t) = (1)/(3) (-(d[I^(-)])/(d t))`
`(1)/(2) xx (d[SO_(4)^(2-)])/(d t) = (1)/(3) xx (9)/(2)`
`:. (d[SO_(4)^(2-)])/(d t) = 3 mol L^(-1)s^(-1)`.