Defination of Terms Used in Reaction Kinetics Chapter

Activation Energy  -  The difference in energy between the reactants and the transition state that is the energy barrier the reactants must overcome to achieve a chemical reaction.

Catalyst  -  A substance that lowers the activation energy for a chemical reaction without being chemically altered by the reaction.

Elementary Step  -  A reaction that represents a single collision or intramolecular step in a reaction mechanism.

Integrated Rate Law  -  The integral (a calculus operation) of the rate law, this form of the rate law shows the dependence of the concentration of reactants on time of reaction.

Intermediate  -  A species that is both produced and consumed in a chemical reaction. An intermediate does not appear in the overall reaction expression but is proposed to be produced in one elementary step and consumed in another.

Kinetics  -  The study of the rates and mechanisms of chemical reactions.

Mechanism  -  The series of elementary steps that combine to produce the path molecules take from reactant(s) to product(s) in a chemical reaction.

Method of Initial Rates  -  A series of experiments wherein the concentration of one reagent at a time is varied and the initial rate (rate at time zero) of the reaction is measured. By comparing the change in concentration to the change in rate, it is possible to determine the order of each reagent in a reaction.

Order  -  In the rate law of a reaction, the power to which the concentration of a reagent is raised. Or, the sum of the powers on the concentration terms in the rate law.

Rate  -  The speed of a reaction measured in amount of reagent consumed or product produced per unit time.

Rate Law  -  An expression of the dependence of the rate of a reaction on the concentrations of reactants.

Reaction Coordinate Diagram  -  A plot of free energy versus the reaction coordinate for a reaction that provides a pictorial representation of the lowest energy path from reactants to products.

Transition State  -  The species with the highest energy between reactant and product on a reaction coordinate diagram, it is a short-lived species that represents a combination of product-like and reactant-like properties.