In kinetics, what primarily determines the rate of reaction?

The rate of a chemical reaction is primarily determined by the concentration of the reactants involved in the rate-determining step, which is often the slowest step in a reaction mechanism. In a multi-step reaction, the slowest step governs how quickly the entire reaction can proceed. This is because the rate of the slow step effectively sets the pace for the reaction as a whole, and its rate can often be expressed in terms of the concentrations of the reactants involved in that step.

When the concentrations of the reactants increase, the likelihood of collision between the molecules of those reactants increases, leading to a higher rate of reaction—as long as those reactants are part of the rate-determining step. This is rooted in the principles of collision theory and the fact that more reactant molecules in a given volume facilitate more frequent collisions, thereby increasing the chance of the necessary activation energy being met for the reaction to proceed.

In contrast, other choices discuss factors that are not the primary determinants of reaction rates: the concentration of products does not affect the rate of the forward reaction under typical conditions. While catalysts can influence reaction rates by lowering activation energies, their presence alone does not solely define the rate; they simply modify it. Temperature does influence reaction rates