Question

For the following mechanism, $P + Q \xrightleftharpoons[K_{B}]{K_{A}} PQ \xrightleftharpoons[K_{D}]{K_{C}} R$ at equilibrium $\frac{[R]}{[P][Q]}$ is
[k represents rate constant]

• A. $\frac {K_{A} . K_{B}}{K_{C} .K_{D}}$
• B. $\frac {K_{A}. K_{B}}{K_{B}. K_{C}}$
• C. $\frac {K_{B}. K_{D}}{K_{A}. K_{C}}$
• D. $\frac {K_{A} .K_{C}}{K_{B}. K_{D}}$

Answer 1

Answer: (D)

$\frac{K_{A}}{K_{B}} =\frac {[PQ]}{[P][Q]} \,\,\,\,\,\,.......(i)$
$\frac {K_{C}}{K_{D}}=\frac{[R]}{[PQ]} \,\,\,\,\,\,\,\,.........(ii)$
On multiply equations (i) and (ii) we get
$\frac {K_{A}K_{C}}{K_{B}K_{D}} =\frac {[R]}{[P][Q]}$