Reactivity 2 / IB Chemistry / Reactivity 2.2 (Including HL and Worksheets )

Reactivity 2.2—How fast? The rate of chemical change

Reactivity 2.2.1—The rate of reaction is expressed as the change in concentration of a particular reactant/product per unit time.
Reactivity 2.2.2—Species react as a result of collisions of sufficient energy and proper orientation.
Reactivity 2.2.3—Factors that influence the rate of a reaction include pressure, concentration, surface area, temperature and the presence of a catalyst.
Reactivity 2.2.4—Activation energy, Ea, is the minimum energy that colliding particles need for a successful collision leading to a reaction.
Reactivity 2.2.5—Catalysts increase the rate of reaction by providing an alternative reaction pathway with lower Ea.

Reactivity 2.2.6—Many reactions occur in a series of elementary steps. The slowest step determines the rate of the reaction.
Reactivity 2.2.7—Energy profiles can be used to show the activation energy and transition state of the rate-determining step in a multistep reaction.
Reactivity 2.2.8—The molecularity of an elementary step is the number of reacting particles taking part in that step.
Reactivity 2.2.9—Rate equations depend on the mechanism of the reaction and can only be determined experimentally.
Reactivity 2.2.10—The order of a reaction with respect to a reactant is the exponent to which the concentration of the reactant is raised in the rate equation.
The order with respect to a reactant can describe the number of particles taking part in the rate-determining step.
The overall reaction order is the sum of the orders with respect to each reactant.
Reactivity 2.2.11—The rate constant, k, is temperature dependent and its units are determined from the overall order of the reaction.
Reactivity 2.2.12—The Arrhenius equation uses the temperature dependence of the rate constant to determine the activation energy.
Reactivity 2.2.13—The Arrhenius factor, A, takes into account the frequency of collisions with proper orientations.