Chlorine dioxide oxidizes iodide ion in aqueous solution to iodine; chlorine dioxide is reduced to chlorite ion.
2ClO2(aq)+ 2I(aq) →2ClO2(aq) + I2(aq)
The order of the reaction with respect to ClO2 was determined by starting with a large excess of I, so that its concentration was essentially constant. Then
Rate = k[ClO2]m[I]n = kʹ [ClO2]m
where kʹ = k[I]n. Determine the order with respect to ClO2 and the rate constant k by plotting the following data assuming firstand then second-order kinetics. [Data from H. Fukutomi and G. Gordon, J. Am. Chem. Soc., 89, 1362 (1967).]
Time (s) [ClO2] (mol/L)
0.00 ........................ 4.77 × 104
1.00........................ 4.31 × 104
2.00........................ 3.91 × 104
3.00........................ 3.53 × 104
5.00........................ 2.89 × 104
10.00....................... 1.76 × 104
30.00....................... 2.4 × 105
50.00........................ 3.2 × 106