The correct difference between first- and second-order reactions is that
easy
ChemicalKinetics
2018
chemistry
A first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed
The half-life of a first-order reaction does not depend on [A]0ā; the half-life of a second-order reaction does depend on [A]0ā
The rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations
The rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations
Explanation
To solve this problem, we need to understand the characteristics of first-order and second-order reactions.Let's analyze each option:ā¢ Option 1: A first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed. This statement is incorrect. Both first-order and second-order reactions can be catalyzed.ā¢ Option 2: The half-life of a first-order reaction does not depend on [A]0ā;
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the half-life of a second-order reaction does depend on
[A]0ā.
This statement is correct.
- For a first-order reaction, the half-life
(t1/2ā)
is given by
t1/2ā=kln2ā,
which is independent of the initial concentration
[A]0ā.
- For a second-order reaction, the half-life
(t1/2ā)
is given by
t1/2ā=k[A]0ā1ā,
which depends on the initial concentration
[A]0ā.
ā¢ Option 3: The rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations.
This statement is incorrect.
- The rate of a first-order reaction is directly proportional to the concentration of the reactant.
- The rate of a second-order reaction is also dependent on the concentration of the reactants.
ā¢ Option 4: The rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations.
This statement is incorrect.
- Both first-order and second-order reactions have rates that depend on reactant concentrations.
Therefore, the correct option is Option 2, which accurately describes the difference in half-life dependency on initial concentration between first-order and second-order reactions.