Overview of Chemical Kinetics
A reaction rate is the speed at which reagents are consumed and products are created. Chemical Kinetics is the study of the rate of chemical reactions. Because the rate of a chemical reaction depends on its pathway, different kinetics may apply for the same overall transformation if it can occur through a variety of mechanisms. Path dependence fundamentally distinguishes the propositions of Chemical Kinetics from those of Chemical Thermodynamics. Chemical Thermodynamics depends solely on the comparison of the initial and final state of the system and surroundings, without recourse to discussion of the reaction pathway, unlike Chemical Kinetics. The use of a catalyst, for example, will change the kinetics of a reaction, but it will not change the position of equilibrium, which is a thermodynamic function.
Chemical Kinetics on the MCATChemical Kinetics problems involving number crunching are rare on the MCAT. However, conceptual questions involving Chemical Kinetics are very common on the test. Chemical kinetics lends itself especially well to the MCAT passage format where passages presenting data can lead to questions involving inference of reaction order, for example, or where the application of kinetics principles allows one to judge among various reaction mechanisms. In the construction of multiple choice questions, the MCAT writers are also fond of questions that make sure students don't confuse the propositions of Chemical Kinetics, which depend on the reaction pathway, with the concepts of Chemical Thermodynamics, which do not depend on the mechanism.