Kinetics Definitions Flashcards
Rate of reaction
The speed at which reactants are used up or products are formed
Or…
The change in concentration of reactants or products per unit time
Collision theory
A reaction can occur only when two particles collide in the correct orientation and with E> or equal to activation energy
Activation energy
The minimum energy that colliding particles must have before collision results in a chemical reaction
Transition state
The highest energy species on the reaction pathway between reactants and products; the highest point on a potential energy profile
Maxwell-Boltzmann distribution
A graph showing the distribution of molecular kinetic energies in a sample of gas at a particular temperature
Catalyst
A substance that increases the rate of a chemical reaction without itself being used up in the reaction
Rate equation
An experimentally determined equation relating the rate of reaction to the concentration of substances in the reaction mixture
Rate constant
A constant of proportionality relating the concentrations in the experimentally determined rate equation to the rate of a chemical reaction
Order of reaction
The power of the reactant’s concentration in the experimentally determined rate equation
Overall order of reaction
The sum of the powers of concentration terms in the experimentally determined rate equation
Reaction mechanism
A series of steps that make up a more complex reaction. Each step involves a maximum of two molecules colliding
Rate determining step
The slowest step in a reaction mechanism
Molecularity
The number of ‘molecules’ that react in a particular step (usually the rate determining step)
Arrhenius equation
An equation showing the variation of rate constant with temperature:
k= Ae to the power of -Ea/RT
