Chapter 7 Rate of chemical reactions Flashcards
Acid rain
Rainwater which has reacted with acidic emissions from industry and vehicles and which has a pH of less than 5.5.
Activation energy
The minimum energy required by reactants for a chemical reaction to occur, symbol Ea. This energy is required to break the bonds between atoms in the reactants to allow products to form.
Adsorption
The attraction and binding or sticking of molecules or particles of one substance to the surface of another.
Catalysis
The increase in the rate of a chemical reaction because of the presence of a catalyst.
Catalyst
A substance which increases the rate of a chemical reaction but which is not consumed in the reaction. The catalyst provides an alternative reaction pathway with a lower activation energy.
Collision theory
A theoretical model which accounts for the rates of chemical reactions in terms of collisions between particles occurring during a chemical reaction.
Energy profile diagram
A diagram which shows the energy changes during the course of a chemical reaction.
Heterogenous catalyst
A catalyst which has a different physical state (phase) from the reactants and products.
Homogenous catalyst
A catalyst which has the same physical state (phase) as the reactants and products.
Kinetic energy
The energy that a particle or body has due to its motion. (KE = 1/2 mv^2)
Maxwell-Boltzmann distribution curve
A graph of kinetic energy against number of particles that shows the range of energies in a sample of a gas or a liquid at a given temperature. Also known as a kinetic energy distribution diagram.
Photochemical smog
Atmospheric pollution produced through the action of sunlight on nitrogen oxides and unburned hydrocarbons to form ozone and other pollutants. The nitrogen oxides are formed at high temperature reactions such as those that occur in car and engines and lightning strikes.
Reaction pathway
A series of chemical reactions which converts a starting material into a product in a number of steps.
Transition state
An intermediate arrangement of atoms in a reaction which occurs when sufficient energy is absorbed for the activation energy to be reached. It represents the stage of maximum potential energy in the reaction. Bond breaking and bond forming are both occurring at this stage, and the arrangement of atoms is unstable.
