Question

The rate of the reaction is given by rate, $r=k[H^{+}{]}^n$ If the rate becomes $100$ times when the pH changes from $2$ to $1$ the order of the reaction is

• A. 0
• B. 1
• C. 2
• D. 3

Answer 1

Answer: (C)

$r=k{\left[H^{+}\right]}^n$
Exp .(l) $r_1=k{\left[10^{-2}\right]}^n$
(If $pH=2$ then $\left[H^{+}\right]=10^{-2}$ )
Exp. (II) $100r_1=k{\left[10^{-1}\right]}^n$
(If $pH=1$ then $\left[H^{+}\right]=10^{-1}$ )
$\frac{\text{Exp}.(II)}{\text{Exp}.(II)}=\frac{100r_1}{r_1}$
$=\frac{k[0.1{]}^n}{k[0.01{]}^n}=\frac{100}{1}$
$={\left[\frac{10}{1}\right]}^n$ or $n=2$
Order of reaction is $2$ .