Question

What is the rate law for the reaction of iodide ion with persulfate ion?

1) Rate = k[I-][S2O8²-]
2) Rate = k[I-]²[S2O8²-]
3) Rate = k[I-][S2O8²-]²
4) Rate = k[I-]²[S2O8²-]²

Answer 1

The rate law for the reaction between iodide ions and persulfate ions is rate = k[I-][S2O8²-], indicating that the reaction is first-order with respect to each reactant.

Step-by-step explanation:

The rate law for the reaction of iodide ion with persulfate ion is determined by experimental data which suggests that the reaction is first order with respect to both reactants. Based on the given information that the rate law agrees with the experimentally determined rate law and the description of a first-order reaction in each reactant, the correct rate law for the reaction can be described as: rate = k[I⁻][S2O8²⁻]. This means that the reaction rate is directly proportional to the concentration of iodide ions and the concentration of persulfate ions. Any catalyst such as iron ions would not appear in the rate law as they are not consumed in the reaction.