Orders of reaction

Orders of reaction

• how concentration of a reactant affects rate

Half life

• the half life of a reaction is the time taken from concentration to decrease by a half

• the second half life is the time taken from the end of the first half life

Zero order reaction

• as the concentration of the reactant decreases the rate of reaction remains constant and the reactant decreases at a constant value

• rate = k

• 

First order reaction

• as the concentration of the reactant decreases the rate of change of [R] decreases

• rate = k[R]

• half lives are identical

• 

Second order reaction

• as the concentration of the reactant decreases the rate of reaction changes rapidly

• rate = k[R]²

• 

• 

Rate equation

• for A + B + C —> products

• rate is directly proportional to [A] which is directly proportional to [B] which is directly proportional to [C]

• rate = k[A]^0 x [B]^1 x [C]²

• k = rate constant

• where the order is determined experimentally from reactant rate/concentration graph