# 14: Chemical Kinetics

• 14.1: The Rate of a Chemical Reaction
In this Module, the quantitative determination of a reaction rate is demonstrated. Reaction rates can be determined over particular time intervals or at a given point in time. A rate law describes the relationship between reactant rates and reactant concentrations.
• 14.2: Measuring Reaction Rates
The method for determining a reaction rate is relatively straightforward. Since a reaction rate is based on change over time, it must be determined from tabulated values or found experimentally. With the obtained data, it is possible to calculate the reaction rate either algebraically or graphically.
• 14.3: Effect of Concentration on Reaction Rates: The Rate Law
Typically, reaction rates decrease with time because reactant concentrations decrease as reactants are converted to products. Reaction rates generally increase when reactant concentrations are increased. This section examines mathematical expressions called rate laws, which describe the relationships between reactant rates and reactant concentrations. Rate laws are mathematical descriptions of experimentally verifiable data.
• 14.4: Zero-Order Reactions
The rates of zero-order reactions is apparently independent of reactant concentrations. This means that the rate of the reaction is equal to the rate constant, k, of that reaction, but clearly a zero-order process cannot continue after a reactant has been exhausted. Just before this point is reached, the reaction will revert to another rate law instead of falling directly to zero  Situations which are apparently zero order occur when a reaction is catalyzed by attachment to a solid surface (hete
• 14.5: First-Order Reactions
In a first-order reaction, the reaction rate is directly proportional to the concentration of one of the reactants. First-order reactions often have the general form A → products.
• 14.6: Second-Order Reactions
The simplest kind of second-order reaction is one whose rate is proportional to the square of the concentration of one reactant. These generally have the form 2A → products. A second kind of second-order reaction has a reaction rate that is proportional to the product of the concentrations of two reactants. Such reactions generally have the form A + B → products.
• 14.7: Reaction Kinetics: A Summary
For a zeroth-order reaction, a plot of the concentration of any reactant versus time is a straight line with a slope of −k. For a first-order reaction, a plot of the natural logarithm of the concentration of a reactant versus time is a straight line with a slope of −k. For a second-order reaction, a plot of the inverse of the concentration of a reactant versus time is a straight line with a slope of k.
• 14.8: Theoretical Models for Chemical Kinetics
• 14.9: The Effect of Temperature on Reaction Rates
• 14.10: Reaction Mechanisms
• 14.11: Catalysis
• 14.E: Exercises