Question

Consider the following reactions at 300 K.

A$\rightarrow$B

(uncatalysed reaction)

$A\overset{\quad catalyst\quad}{\rightarrow}B$ (catalyst reaction)

The activation energy is lowered by 8.314 KJ mol–1 for the catalysed reaction. How many times the rate of this catalysed reaction greater than that of uncatalysedreaction ? (Given e3.33 = 28)

• A. 15 times
• B. 38 times
• C. 22 times
• D. 28 times

Answer 1

Answer: (D)

28 times

Answer 2

A ® B (uncatalysed reaction) $A \rightarrow B$

(catalyst reaction)

$\text{K = A }\text{e}^{\text{-Ea/RT}}$

$K_{\text{cat}}\text{. = A}e^{\text{-Ea}\left( \text{cat} \right)/RT}$

$\frac{K_{cat}}{K} = e^{\frac{8.314 \times 10^{3}}{8.314 \times 300}} = e^{3.33} = 28times$