Question

For a chemical reaction $A \longrightarrow $ Products, the rate of disappearance of $A$ is given by:
$-\frac{d C_{ A }}{d t}=\frac{K_{1} C_{ A }}{1+K_{2} C_{ A }}$ At very low $C_{ A }$, the reaction is of the ...... order with rate constant ....... :
(Assume $K_{1}$ and $K_{2}$ are lesser than 1 )

• A. $I , K_{1} / K_{2}$
• B. $I , K_{1}$
• C. $II , K_{1} / K_{2}$
• D. $ II, K_{1} / K_{1}+K_{2}$

Answer 1

Answer: (B)

$-\frac{d C_{A}}{d t}=\frac{K_{1} C_{A}}{1+K_{2} C_{A}}$

At very low $C_{A}: 1 \gg K_{2} C_{A} ;\left(1+K_{2} V_{A}\right) \approx 1$

$\therefore $ rate $=-\frac{d C_{A}}{d t}=K_{1} C_{A} ;$ Rate constant $=K_{1}$

order $=1$