Question

For each of the following systems at equilibrium, predict whether the reaction will shift to the right, left, or not be affected by a decrease in the reaction container volume.
A) PCl3(g) + Cl2(g) ⇌ PCl5(g) 1. no shift
2. right shift
3. left shift B) 2 NO(g) ⇌ N2(g) + O2(g)
1. no shift 2. right shift3. left shift C) 2 NO2(g) ⇌ N2O4(g)
1. no shift 2. right shift3. left shift

Answer 1

Answer:

A - right shift

B - no shift

C - right shift

Explanation:

According to Le Chatelier's principle, when a reaction is in equilibrium and one of the factors affecting the rate of reaction is introduced, the equilibrium will shift so as to annul the effects of the constraint.

In this case, decreasing the volume of the reaction's container is equivalent to increasing the pressure of the reaction. When pressure is increased, the reaction will shift towards the side with a lower number of moles.

In A, the total number of moles on the left-hand side of the reaction is two while it is one on the right-hand side. An increase in pressure will, therefore, see the equilibrium shifting to the right-hand side.

In B, the total number of moles on both the right and the left-hand side is two each. An increase in the pressure will have no effect on the equilibrium.

In C, the total number of moles on the left-hand side is two while it is one on the right-hand side. Hence, an increase in the pressure of the reaction will cause a shift in the equilibrium to the right.