The reaction `S_(2)O_(8)^(2-) + 3I^(ɵ) rarr 2SO_(4)^(2-) + I_(3)^(ɵ)` is of first order both with
Channel: Doubtnut
Date: 2020-07-12

The reaction `S_(2)O_(8)^(2-) + 3I^(ɵ) rarr 2SO_(4)^(2-) + I_(3)^(ɵ)` is of first order both with respect to persulphate and iofide ions. Taking the initial concentration as `a` and `b`, respectively, and taking `x` as the concentration of the triofide at time `t`, a differential rate equation can be written.  Two suggested mechanism for the reaction are:  I. `S_(2)O_(8)^(2-)+I^(ɵ) hArr SO_(4)I^(ɵ)+SO_(4)^(2-) ("fast")`  `I^(ɵ)+SO_(4)I^(ɵ) overset(k_(1))rarrI_(2) + SO_(4)^(2-)` (show)  `I^(ɵ) + I_(2) overset(k_(2))rarr I_(3)^(ɵ) ("fast")`  II. `S_(2)O_(8)^(2-) + I^(ɵ) overset(k_(1))rarr S_(2)O_(8) I^(2-)  (slow)`  `S_(2)O_(8)I^(3-) overset(k_(2))rarr2SO_(4)^(2-)+I^(o+) ("fast")`  `I^(o+) + I^(ɵ) overset(k_(3)) rarr I_(2) ("fast")`  `I_(2) + I^(o+) overset(k_(4))rarr I_(3)^(ɵ) ("fast")`  The general difference equation for the above reaction is