activated complex
intermediate configuration of atoms during a chemical reaction with high potential energy
activation energy
minimum energy needed for a chemical reaction to initiate
Arrhenius equation
equation that relates temperature to the rate constant; given as
bimolecular reaction
elementary reaction that occurs between two reactants
catalyst
substance that causes the rate of a chemical reaction to increase
chemical kinetics
field that studies the rates of chemical reactions
collision theory
theory that describes how chemical reactions occur through molecular collisions and why reaction rates vary between reactions
elementary reaction
reaction that takes place in a single step
enzyme
biological molecule that catalyzes a biological reaction
first-order reaction
reaction in which the rate is dependent on the concentration of one of the reactants, raised to the power of one; given as a rate law with the form
heterogeneous catalyst
catalyst that is in a different phase than that of the reactants
homogeneous catalyst
catalyst that is in the same phase as that of the reactants and is present in the reaction medium
instantaneous rate
rate of a chemical reaction at a particular moment
integrated rate law
rate law that defines concentration as a function of time
intermediate
species that is produced in one step and consumed in another step of a chemical reaction
molecularity
number of molecules that participate in the rate-determining step of a chemical reaction
rate constant (k)
constant relating reaction rate to concentrations of reactants
rate expression
mathematical expression that relates rate with a rate constant and concentrations of the reactants; given as the general form
rate-determining step
slowest reaction in a multistep reaction that determines the overall rate
reaction half-life
time it takes for a reactant to drop to half its starting concentration during a chemical reaction
reaction mechanism
exact step or steps required to convert reactants into products
reaction order
sum of the powers that the reactant concentrations are raised to in the rate expression
reaction rate
speed at which a reaction occurs
second-order reaction
reaction in which the sum of the powers that the reactant concentrations are raised to in the rate expression is equal to two; given as a rate law with the form or
termolecular reaction
elementary reaction that occurs between three reactants
unimolecular reaction
elementary reaction with one reactant
zero-order reaction
reaction in which rate is not dependent on reactant concentrations; given as a rate law with the form