CHEM1312H - Effect of Concentration on Reaction Rates

the concentration of the reactant particles

the greater the concentration/number of particles the greater the number of collisions per unit time the greater the reaction rate

the temperature of the reactant mixture

at high temperatures many collisions occur with enough energy to break the bond between reactants causing the reaction rate to be fast

collision theory

the structure and orientation of the colliding particles

the physical state of the reactants

a reaction is limited by the phase of the reactants and the surface area of solids (the presence of a catalyst; dk why this is important so figure out later)

rate laws (rate equations)

mathematical expressions that describe the relationship between the rate of a chemical reaction and the concentration of its reactants

differential rate law

where the rate of a reaction is directly proportional to the concentration of each reactant raised to a power

integrated rate law

describes the change in the concentrations of one or more reactants as a function of time

rate equations

-the rate of a reaction is directly proportional to the concentration of each reactant raised to a power

-ex: rate = k[A]^m[B]ⁿ

-m and n: reaction order of reaction with respect to A and B

-overall order of the reaction = m + n

reaction order

usually an integer (can be a decimal and can be positive or negative), determines how the rate depends on the concentration of the reactant (rate = k[A]ⁿ

the order of a reaction

-if the reaction is zero-order (n = 0), the rate is independent of the concentration of A

-if the reaction is first-order (n = 1), the rate is directly proportional to the concentration of A

-if the reaction is second-order (n = 2), the rate is proportional to the square of the concentration of A

the rate constant, k

-specific for a particular reaction at a particular temperature

-independent of reactant concentrations

units of k

-for zero-order reactions, rate = k[A]⁰ = k (units = M/sec)

-for first-order reactions, rate = k[A]¹ (units = sec^-1)

-for second-order reactions, rate = k[A]² (units = M^-1 x sec^-1)