http://www.ck12.org Chapter 18. Kinetics
FIGURE 18.7
The addition of a catalyst to a reaction lowers the activation energy, increasing the rate of the reaction. The
activation energy of the uncatalyzed reaction is shown by Ea, while the catalyzed reaction is shown by Ea’. The
heat of reaction (∆H) is unchanged by the presence of the catalyst.- The progress of a chemical reaction can be shown with a potential energy diagram.
- The rate of a chemical reaction can be increased by increasing the concentration, gas pressure, or surface area
of the reactants, increasing the temperature of the reaction, or by the addition of a catalyst.
Lesson Review Questions
Reviewing Concepts
- In what unit is the rate of a chemical reaction typically expressed?
- Does every collision between reacting particles lead to the formation of products? Explain.
- What two conditions must be met in order for a collision to be effective?
- Explain why the activation energy of a reaction is sometimes referred to as a barrier.
- Why is it difficult to study activated complexes?
- Reaction rates can be affected by changes in concentration, pressure, or surface area. Use collision theory to
explain the similarities between the effects that each of these factors has on reaction rate. - What is the effect of a catalyst on the rate of a reaction? Explain how the presence of a catalyst affects the
activation energy of a reaction.
Problems
- A 2.50 M solution undergoes a chemical reaction. After 3.00 minutes, the concentration of the solution is 2.15
M. What is the rate of the reaction in M/s? - Zinc metal reacts with hydrochloric acid. Which of the following would result in the highest rate of reaction?
a. A solid piece of zinc in 1 M HCl