Question

For a reaction scheme, $A\stackrel{k_1}{\to }B\stackrel{k_2}{\to }C$, if the rate of formation of $B$ is set to be zero then the concentration of $B$ is given by:

• A. $k_1{k}_2\left[A\right]$
• B. $\frac{k_1}{k_2}\left[A\right]$
• C. $(k_1-k_2)\left[A\right]$
• D. $k_1+k_2\left[A\right]$

Answer 1

The correct option is B $\frac{k_1}{k_2}\left[A\right]$

$A\stackrel{k_1}{\to }B\stackrel{k_2}{\to }C$
Rate of formation of $B$ is:
$\frac{d\left[B\right]}{dt}=k_1\left[A\right]-k_2\left[B\right]$
Given,
$\frac{d\left[B\right]}{dt}=0$
$\Rightarrow 0=k_1\left[A\right]-k_2\left[B\right]$
$\Rightarrow k_1\left[A\right]=k_2\left[B\right]$
$\Rightarrow \left[B\right]=\frac{k_1}{k_2}\left[A\right]$