Question

A mixture of Nitrogen and Hydrogen is at an initial pressure of $200atm$. If $20\%$ of the mixture reacts by the times equilibrium is reached, the equilibrium pressure of the mixture is:

• A. $160atm$
• B. $180atm$
• C. $170atm$
• D. data insufficient

Answer 1

The correct option is B $180atm$

$N_2+3H_2\rightleftharpoons 2N{H}_3$

$x$ mol $3x$ mol $\to 2x$ mol

$\therefore \Delta n=-2x$ mol.

$\therefore$ If $20\%$ i.e. 40 atm of mixture reacted then the pressure of $N{H}_3$ formed will be only 20 atm.

So, there will be a drop of 20 atm in pressure.

So, final pressure is 180 atm.