# 2.5.2: The Rate of a Chemical Reaction


The rate of a chemical reaction is the change in concentration over the change in time.

## Introduction

The rate of a chemical reaction is the change in concentration over the change in time and is a metric of the "speed" at which a chemical reactions occurs and can be defined in terms of two observables:

1. The Rate of Disappearance of Reactants $-\dfrac{\Delta[Reactants]}{\Delta{t}} \nonumber$ Note this is negative because it measures the rate of disappearance of the reactants.
2. The Rate of Formation of Products $\dfrac{\Delta{[Products]}}{\Delta{t}} \nonumber$ This is the rate at which the products are formed.

They both are linked via the balanced chemical reactions and can both be used to measure the reaction rate.

## References

1. Petrucci et al. General Chemistry: Principles & Modern Applications, 9th Edition. New Jersey: Prentice-Hall Inc., 2007.
2. Connors, Kenneth. Chemical Kinetics: The Study of Reaction Rates in Solution. New York City: VCH Publishers, Inc., 1990.

## Problems

1. Consider the reaction $$2A + B \longrightarrow C$$. The concentration of [A] is 0.54321M and the rate of reaction is $$3.45 \times 10^{-6} M/s$$. What Concentration will [A] be 3 minutes later?
2. Consider the reaction $$A + B \longrightarrow C$$. The rate of reaction is 1.23*10-4. [A] will go from a 0.4321 M to a 0.4444 M concentration in what length of time?
3. Write the rate of the chemical reaction with respect to the variables for the given equation. $2A+3B \rightarrow C+2D \nonumber$
4. True or False: The Average Rate and Instantaneous Rate are equal to each other.
5. How is the rate of formation of a product related to the rates of the disappearance of reactants.

## Contributors

• Albert Law, Victoria Blanchard, Donald Le

2.5.2: The Rate of a Chemical Reaction is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.