Dr. Ken Etticks investigates the oxidation of iodide ion by arsenic acid in aqueous solution. The reaction is:
3(aq) + H₃AsO₄(aq) + 2 H+ (aq) → 15 (aq) + H₃}AsO₃(aq) + H₂O(l)
During his experiment the following data were collected:
[I] = 2.78×10² M at t = 60.0 s, and
[I] = 1.42×10² M at t = 80.0 s.
Calculate the average rate of reaction during this time interval._______M/s