Overall reaction order

Definition

Overall reaction order is the sum of the exponents of the concentration terms in a rate law equation. It indicates how the rate of reaction depends on the concentration of reactants.

5 Must Know Facts For Your Next Test

1. The overall reaction order is determined by adding up the individual orders with respect to each reactant.
2. A reaction can have an overall order that is zero, fractional, or even negative.
3. The units of the rate constant vary depending on the overall reaction order.
4. Knowing the overall reaction order helps predict how changes in concentrations affect the reaction rate.
5. Determining the overall reaction order often requires experimental data and cannot always be deduced from just a balanced equation.

Review Questions

• What does the overall reaction order represent in a rate law equation?
• How do you calculate the overall reaction order for a given rate law?
• What are some possible values (e.g., zero, fractional) for an overall reaction order?

Related terms

Rate Law: An equation that relates the rate of a chemical reaction to the concentration of its reactants.

Reaction Order: The exponent to which a reactant concentration is raised in a rate law equation.

Rate Constant: A proportionality constant in the rate law equation that is specific to a particular reaction at a given temperature.