Question

For an equilibrium reaction involving gases, the forward reaction is first order while the reverse reaction is second order. The units of $K_p$ for forward equilibrium is:

• A. $atm$
• B. ${atm}^2$
• C. ${atm}^{-1}$
• D. ${atm}^{-2}$

Answer 1

The correct option is A $atm$

We know that,

$K_{eq}=\frac{K_f}{K_b},K_f\to$ rate constant of forward reaction

$K_b\to$ rate constant of backward reaction

Now, forward reaction is of shift order, so unit of $K_f$ is $\frac{1}{sec}$

$K_b$ is $\frac{1}{atmsec}$

Now, unit of $K_{eq}=\frac{1}{sec}\times atmsec=atm$