The Foundations of Chemistry

16

OUTLINE

16-1 The Rate of a Reaction

Factors That Affect Reaction Rates

16-2 Nature of the Reactants

16-3 Concentrations of Reactants:

The Rate-Law Expression

16-4 Concentration versus Time:

The Integrated Rate Equation

16-5 Collision Theory of Reaction

Rates

16-6 Transition State Theory

16-7 Reaction Mechanisms and the

Rate-Law Expression

16-8 Temperature: The Arrhenius

Equation

16-9 Catalysts

OBJECTIVES

After you have studied this chapter, you should be able to

• Express the rate of a chemical reaction in terms of changes in concentrations of

reactants and products with time

• Describe the experimental factors that affect the rates of chemical reactions


• Use the rate-law expression for a reaction—the relationship between concentration and

rate

• Use the concept of order of a reaction


• Apply the method of initial rates to find the rate-law expression for a reaction


• Use the integrated rate-law expression for a reaction—the relationship between

concentration and time

• Analyze concentration-versus-time data to determine the order of a reaction


• Describe the collision theory of reaction rates


• Describe the main aspects of transition state theory and the role of activation energy in

determining the rate of a reaction

• Explain how the mechanism of a reaction is related to its rate-law expression


• Predict the rate-law expression that would result from a proposed reaction mechanism


• Identify reactants, products, intermediates, and catalysts in a multistep reaction

mechanism

• Explain how temperature affects rates of reactions


• Use the Arrhenius equation to relate the activation energy for a reaction to changes in

its rate constant with changing temperature

• Explain how a catalyst changes the rate of a reaction


• Describe homogeneous catalysis and heterogeneous catalysis

A burning building is an example

of a rapid, highly exothermic

reaction. Firefighters use basic

principles of chemical kinetics to

battle the fire. When water is

sprayed onto a fire, its evaporation

absorbs a large amount of energy;

this lowers the temperature and

slows the reaction. Other common

methods for extinguishing fires

include covering them with CO 2 (as

with most household extinguishers),

which decreases the supply of

oxygen, and backburning (for grass

and forest fires), which removes

combustible material. In both cases,

the removal of a reactant slows (or

stops) the reaction.