Question

Consider the following reaction system which is taking place in a closed vessel at constant temperature.
$A\left(g\right)+B\left(g\right)\rightleftharpoons AB\left(g\right)$
Which of the following is NOT true about this system at equilibrium?

• A. Increasing the volume will produce more $AB$
• B. Increasing the volume will produce less $AB$
• C. Increasing the pressure will produce more $AB$
• D. There is no effect of increasing pressure or volume.

Answer 1

The correct option is A Increasing the volume will produce more $AB$

Change in gaseous moles for this reaction:
$\Delta n_g=1-2=-1$

When pressure is increased , $\frac{n_g}{V}\uparrow$ , the reaction goes where $n_g$ decreases. For $\Delta n_g<0$, it decreases in the forward direction.
So when $\Delta n_g<0$, and $P\uparrow$, the reaction goes in forward direction.

When volume is increased , $\frac{n_g}{V}\downarrow$ , the reaction goes where $n_g$ increases. For $\Delta n_g<0$, it increases in the backward direction.

So when $\Delta n_g<0$, and $V\uparrow$, the reaction goes in backward direction.

Hence we can see that from given options, (a) is correct.