Question

Suppose the reaction system

UO₂(s) + 4HF(g) UF₄(g) + 2H₂O(g)

has already reached equilibrium. Predict the effect that each of the following changes will have on the equilibrium position. Tell whether the equilibrium will shift to the right, will shift to the left, or will not be affected.

a. More UO₂(s) is added to the system.

b. The reaction is performed in a glass reaction vessel; HF(g) attacks and reacts with glass.

c. Water vapor is removed.

Short answer

a. The equilibrium will not be affected.

b. The equilibrium will shift to the left.

c. The equilibrium will shift to the right.

Step-by-step solution

Explanation for a

According to Le Châtelier's Principle, the addition of pure liquids and solids to the system has no effect on the equilibrium. Hence, the equilibrium will not be affected when more UO₂(s) are added to the system.

Explanation for b

By reacting with the glass, HF will be eliminated. When HF is removed from the reaction, the equilibrium shifts to the left, generating more HF. Therefore, the equilibrium will shift to the left when the reaction is performed in a glass reaction vessel.

Explanation for c

When water vapor (the product) is taken from the reaction, the reaction will generate more water vapor. As a result, the equilibrium will shift to the right.