http://www.ck12.org Chapter 18. Kinetics
18.2 Rate Laws
Lesson Objectives
- Use a rate law to describe the concentration dependence of a reaction rate.
- Determine the rate law for a reaction by analysis of experimental data.
- Calculate the specific rate constant from experimental data.
Lesson Vocabulary
- first-order reaction
- rate law
- specific rate constant
Check Your Understanding
Recalling Prior Knowledge
- What is a reaction rate?
- Why does the rate of a reaction depend on the concentrations of the reactants?
The rate of a chemical reaction increases as the concentrations of the reactants increase. The specific relationships
between each concentration and the reaction rate are given by a rate law. In this lesson, you will learn how to write
and analyze rate laws for various reactions.
Rate Law Concept
Consider a simple chemical reaction in which reactant A is converted into product B according to the equation below.
A→B
As seen in the last lesson, the rate of reaction is given by the change in concentration of A as a function of time. If
this reaction proceeds by a single-step mechanism, which we will explain more completely later in this chapter, the
rate of disappearance of A is also proportional to the concentration of A.
−
∆[A]
∆t