The oxidation of iodide ion by peroxydisulfate ion is described by the equation,

3I-

(aq) + S2O8

2-

(aq) → I3

-

(aq) + 2SO4

2-

If −∆[28

2−]

∆

⁄ = 1.5 × 10-3 mol. dm-3

s

-1

, what is the rate of consumption of I-

and formation of 3

− and 4

2−?