For the following reaction system at equilibrium, which one of the changes below would cause the equilibrium to shift to the right?

Question

Br2(1) + 2
0(g) = 2NOBr(g) + heat
• Add some NOBr.
• Add some Br2.
• Increase the volume of the reaction vessel.
Remove some NO.
Decrease the temperature.

Answer 1

To determine which change would shift the equilibrium of the reaction

\[ \text{Br}_2(g) + 2\text{NO}(g) \rightleftharpoons 2\text{NOBr}(g) + \text{heat} \]

to the right, we can apply Le Chatelier's principle, which states that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change.

Here are the effects of the proposed changes:

1. Add some NOBr: Adding a product will shift the equilibrium to the left to produce more reactants, so this does not shift it to the right.

2. Add some Br2: Adding a reactant will shift the equilibrium to the right to produce more products. This change will shift the equilibrium to the right.

3. Increase the volume of the reaction vessel: Increasing the volume of the reaction vessel decreases the pressure of the system. The equilibrium will shift toward the side with more moles of gas to counteract the change. In this case, there are 3 moles of gas on the reactants' side (1 Br2 + 2 NO) and 2 moles of gas on the products' side (2 NOBr). Thus, this will shift to the left, not the right.

4. Remove some NO: Removing a reactant will cause the equilibrium to shift to the left to produce more reactants, so this does not shift it to the right.

5. Decrease the temperature: Since the reaction produces heat (exothermic), decreasing the temperature will shift the equilibrium to the right to produce more heat. This change will also shift the equilibrium to the right.

In summary, the changes that would shift the equilibrium to the right are:

• Add some Br2.
• Decrease the temperature.

The correct answers are "Add some Br2" and "Decrease the temperature."