Question detail
What is the rate equation for a reaction that is first order with respect to reactant A?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Rate equations (A-level only)
Question
- A. Rate = k[A]
- B. Rate = k[A]^2
- C. Rate = k[A][B]
- D. Rate = k[A]^3
Answer
Rate = k[A]
Explanation
The rate equation for a first-order reaction is directly proportional to the concentration of the reactant raised to the power of one. Therefore, the correct form is Rate = k[A].
Common mistake
Incorrect Rate Equation Formation
Students often confuse the order of reaction with the coefficients in the balanced equation when writing rate equations.
To write the correct rate equation, identify the order of each reactant based on experimental data, not the coefficients. For example, if the rate law is rate = k[A]^2[B]^1, this indicates that the reaction is second order with respect to A and first order with respect to B. Ensure to use the correct orders derived from initial rate data.
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