Final answer:
The initial rate of reaction is higher than the rate at later stages, calculated by dividing the change in concentration by the time interval for each respective period.
Step-by-step explanation:
To determine how the initial rate of reaction of hydrogen peroxide decomposition differs between time 0 and 300 seconds and time 1800 to 3000 seconds, we must calculate the rate at which the concentration of H2O2 changes during these intervals. For the initial rate, between 0 and 300 seconds, the concentration decreases from 2.0 M to 1.6 M. The rate can be found by dividing the change in concentration (2.0 M - 1.6 M = 0.4 M) by the time interval (300 s).
For the latter rate, between 1800 and 3000 seconds, the concentration decreases from 0.72 M to 0.15 M. Similarly, the rate is the change in concentration (0.72 M - 0.15 M = 0.57 M) divided by the time interval (3000 s - 1800 s = 1200 s).
Comparing these two rates will show that the initial rate is generally higher than the rate towards the end of the reaction, consistent with the characteristics of first-order reactions, where the rate decreases as the concentration of the reactant decreases.