Question

The correct difference between first and second order reactions is that:

• A. A first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed
• B. The half-life of a first-order reaction does not depend on $[A{]}_0$; the half-life of a second-order reaction depends on $[A{]}_0$
• C. The rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction depends on reactant concentrations
• D. The rate of a first-order reaction depends on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations

Answer 1

The correct option is B The half-life of a first-order reaction does not depend on $[A{]}_0$; the half-life of a second-order reaction depends on $[A{]}_0$

For a first order reaction, $t_{1/2}$= $\frac{0.693}{k}$, which is independent of the initial concentration of the reactant.
For a second order reaction, $t_{1/2}$= $\frac{1}{k[A{]}_o}$, which depends on the initial concentration of the reactant.