Average rate
Definition
The average rate of a chemical reaction is the change in concentration of a reactant or product per unit time over a specific time interval. It gives an overall sense of how quickly the reaction proceeds during that period.
5 Must Know Facts For Your Next Test
- The average rate can be calculated using the formula: $\text{Average Rate} = \frac{\Delta [\text{Reactant or Product}]}{\Delta t}$, where $\Delta$ signifies change and $t$ is time.
- It is typically expressed in units such as Molarity per second (M/s).
- Average rate decreases as the reaction progresses due to the consumption of reactants.
- In a graph of concentration versus time, the average rate corresponds to the slope of the line connecting two points on the curve.
- For reactions with multiple steps, each step has its own average rate and these can vary significantly.
Review Questions
- How do you calculate the average rate of a reaction?
- What units are commonly used for expressing the average rate?
- Why does the average rate generally decrease as a reaction proceeds?
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Related terms
Instantaneous Rate: The instantaneous rate is the change in concentration at a specific moment in time, typically determined by taking the derivative of concentration with respect to time.
Rate Law: A mathematical expression that describes the relationship between the concentrations of reactants and the reaction rate.
Reaction Order: An exponent in the rate law that indicates how sensitive the reaction rate is to changes in reactant concentration.
