Multiple Choice
In a chemical reaction where A is being converted to B, if the concentration of [A] at t₀ = 0.325 M and 35 seconds later [A] = 0.145 M, what is the average rate of reaction over the 35-second time interval?
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15. Chemical Kinetics
Average Rate of Reaction
Multiple Choice
Which of the following best describes the difference between the average rate of reaction and the instantaneous rate of reaction?
A
The average rate is measured over a time interval, while the instantaneous rate is measured at a specific moment.
B
The average rate is measured only at the start of the reaction, while the instantaneous rate is measured at the end.
C
The average rate uses only the final concentration, while the instantaneous rate uses only the initial concentration.
D
The average rate is always greater than the instantaneous rate.
Verified step by step guidance1
Understand that the rate of a chemical reaction describes how fast reactants are converted into products over time.
Recognize that the average rate of reaction is calculated by measuring the change in concentration of a reactant or product over a specific time interval. Mathematically, it is expressed as \(\text{Average Rate} = -\frac{\Delta [\text{Reactant}]}{\Delta t}\) or \(\frac{\Delta [\text{Product}]}{\Delta t}\), where \(\Delta\) indicates change over the time interval \(\Delta t\).
Know that the instantaneous rate of reaction refers to the rate at a particular moment in time. It is found by taking the derivative of concentration with respect to time, written as \(\text{Instantaneous Rate} = -\frac{d[\text{Reactant}]}{dt}\) or \(\frac{d[\text{Product}]}{dt}\).
Compare the two: the average rate gives an overall rate between two points in time, while the instantaneous rate gives the exact rate at a single point in time.
Conclude that the key difference is that the average rate is measured over a time interval, whereas the instantaneous rate is measured at a specific moment.
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