Kinetics Rapid Review for AP Chemistry

By — McGraw-Hill Professional
Updated on Feb 9, 2011

For a more thorough review, refer to these concepts:

Rapid Review

  • Kinetics is a study of the speed of a chemical reaction.
  • The five factors that can affect the rates of chemical reaction are the nature of the reactants, the temperature, the concentration of the reactants, the physical state of the reactants, and the presence of a catalyst.
  • The rate equation relates the speed of reaction to the concentration of reactants and has the form: Rate = k[A]m[B]n … where k is the rate constant and m and n are the orders of reaction with respect to that specific reactant.
  • The rate law must be determined from experimental data. Review how to determine the rate law from kinetics data.
  • When mathematically comparing two experiments in the determination of the rate equation, be sure to choose two in which all reactant concentrations except one remain constant.
  • Rate laws can be written in the integrated form.
  • If a reaction is first order, it has the rate law of Rate = k[A]; ln [A]t –ln [A]0 = –kt; a plot of ln[A] versus time gives a straight line.
  • If a reaction is second order, it has the form of (integrated rate law); a plot of versus time gives a straight line.
  • The reaction half–life is the amount of time that it takes the reactant concentration to decrease to one–half its initial concentration.
  • The half–life can be related to concentration and time by these two equations (first and second order, respectively): and t1/2 = 1/k[A]0 to apply these equations.
  • The activation energy is the minimum amount of energy needed to initiate or start a chemical reaction.
  • Many reactions proceed from reactants to products by a series of steps called elementary steps. All these steps together describe the reaction mechanism, the pathway by which the reaction occurs.
  • The slowest step in a reaction mechanism is the rate–determining step. It determines the rate law.
  • A catalyst is a substance that speeds up a reaction without being consumed in the reaction.
  • A homogeneous catalyst is in the same phase as the reactants, whereas a heterogeneous catalyst is in a different phase from the reactants.
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