Question

The hydrolysis of an ester was carried out with 0.1 M $H_{2}S{O}_4$ and 0.1 M HCl separately. Which of the following expressions between the rate consists is expected? The rate expression being rate = $k\left[H^{\oplus }\right]\left[ester\right]$

• A. $k_{HCl}=k_{H_{2}S{O}_4}$
• B. $k_{HCl}>k_{H_{2}S{O}_4}$
• C. $k_{HCl}<k_{H_{2}S{O}_4}$
• D. $k_{H_{2}S{O}_4}=k_{HCl}$

Answer 1

Answer: (B)

$k_{HCl}>k_{H_{2}S{O}_4}$

$\left[H_{2}S{O}_4\right]=0.1M=0.1\times 2=0.2N$

$\left[HCl\right]$ = $0.1N$

In case of $\left[H_{2}S{O}_4\right]$

$r_1=k\left[H^{\oplus }\right]\left[Ester\right]$

$k_{H_{2}S{O}_4}=\frac{r_1}{2N\times \left[Ester\right]}$

In case of HCl, $r_1=k\left[H^{\oplus }\right]\left[Ester\right]$

$k_{HCl}=\frac{r_2}{1N\left[Ester\right]}$

Hence $K_{HCl}>K_{H_{2}S{O}_4}$