Question

b. You have at your disposition the following solutions: [I-] = 0.2M, [I-] = 0.15M, [I-] = 0.1M, [ClO2] = 4.77x10-4M. What kind of experiment can you do to determine the order of the reaction (n) with respect to I-? Briefly describe the experiments and necessary calculations.

Answer 1

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)

to determine the order of the reaction we do 2 experiments

0.2 M I- and [ClO2] = 4.77x10-4M .. and determine the rate by observing the appearance of I2
the second experiment is done with [I-] = 0.15M and [ClO2] = 4.77x10-4M

the ClO2 is constant but the [ ] of the I- is decreased by 25 % and we compare this change to the change in the rate. If it drops by 25% the reaction is first order with respect to I-