When the concentrations of reactant molecules are increased, the rate of the reaction increases. The best explanation for this phenomenon is that as the reactant concentration increases:
A. the average kinetic energy of molecules increases
B. the activation energy increases
C. the frequency of molecular collisions increases
D. the rate constant increases
E. the order of reaction increases
Solution: Let's look at all the answer choices.
A: average kinetic energy is connected to temperature which did not change in this case and is not the answer
B: Increasing concentration of reactants does not increase the activation energy.
C: When there is an increased concentration of reactant molecules, the frequency of their collisions increases as well leading to a higher rate of the reaction. Choice C is the CORRECT answer.
D. the rate constant does not change with increased concentration
E. the order of reaction does not change with increased concentration