Iodide ion catalyzes the decomposition of hydrogen peroxide. The reaction is first-order in H2O2. What is the value of the rate constant, k, if the initial rate is 0.00842 mol/(L·s) and the initial concentration of H2O2 is 0.500 mol/L.

0.01684 s⁻¹

Explanation:

In a first-order reaction, the rate is proportional to the concentration of only one reactant (raised by 1). In this case, the reactant is H₂O₂. Thus, the rate law is the following:

rate = k [H₂O₂]

We have the following data for the initial rate:

rate = 0.00842 mol/(L·s)

[H₂O₂] = 0.500 mol/L

So, we introduce the data in the expression for the rate law to calculate k:

k = rate/[H₂O₂] = (0.00842 mol/L·s)/0.500 mol/L = 0.01684 s⁻¹