Question

For the reversible reaction:

$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)+heat$

The equilibrium shifts in forward direction:

• A. by increasing the concentration of $N{H}_3\left(g\right)$
• B. by decreasing the pressure
• C. by decreasing the concentrations of $N_2\left(g\right)$ and $H_2\left(g\right)$
• D. by increasing pressure and decreasing temperature

Answer 1

The correct option is D by increasing pressure and decreasing temperature

For the reversible reaction:

$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)+heat$ The equilibrium shifts in forward direction by increasing pressure and decreasing temperature.

According to Le-Chatalier principle when equilibrium is disturbed by a change, the system will try to nullify the effect of change to restore the equilibrium.

Thus, when pressure is increased, the equilibrium will shift in a direction in which there is a decrease in the number of moles of gaseous substances. This will nullify the effect of increased pressure. This happens in the forward direction.

Similarly for an exothermic reaction, when the temperature is decreased, the equilibrium shifts in the forward direction.