Q75 / 180 · NEET 2018 · Chemistry

What is the correct difference between first and second order reactions?

A
A first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed.
Correct answer
B
The half-life of a first-order reaction does not depend on ${[A]}_{0}$ ; the half-life of a second-order reaction does depend on ${[A]}_{0}$ .
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.

Solution

\Rightarrow

(t_{\frac{1}{2}}) \propto {(Initial concentration)}^{1 - order of Reaction}

(t_{\frac{1}{2}}) for 1^{st}

order = Independent of Concentration

(t_{\frac{1}{2}}) for 2^{nd}

order

\propto \frac{1}{{[A]}_{0}}

\Rightarrow

Rate of first order reaction

\propto {(A_{0})}^{1}

Rate of second order reaction

\propto {(A_{0})}^{2}

rate of first order reaction and second order reaction depends on initial concentration.

Hence, the correct answer is option: 'B'.