Question

The correct difference between first and second order reactions is that

• A. A first-order reaction can catalyze; a second-order reaction cannot be catalyzed
• B. The half-life of a first-order reaction does not depend on $\left[\right.A\left]\right._{0}$ ; the half-life of a second-order reaction does depend on $\left[\right.A\left]\right._{0}$
• C. 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
• D. 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

Answer 1

Answer: (B)

For first order reaction, $t_{1 / 2}=\frac{0.693}{k},$ which is independent of initial concentration of reactant. $\left(\right.t_{1 / 2}\cancel{ \propto }a\left.\right)$
For second order reaction, $t_{1 / 2}=\frac{1}{k \left[\right. A_{0} \left]\right.},$ which depends on initial concentration of reactant $\left(t_{1 / 2} \propto \frac{1}{a}\right)$