Final answer:
Adding Br₂ to the equilibrium mixture of 2 BrNO(g) ↔ 2 NO(g) + Br₂(g) will cause the equilibrium to shift towards the reactants, decreasing the concentration of NO and increasing the concentration of BrNO, according to Le Chatelier's Principle.
Step-by-step explanation:
Adding Br₂ to the reaction mixture of 2 BrNO(g) ↔ 2 NO(g) + Br₂(g) will affect the equilibrium according to Le Chatelier's Principle. This principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change. In this case, adding more Br₂ will shift the equilibrium towards the reactants to reduce the concentration of added Br₂, resulting in the increased production of BrNO and decreased production of NO.
Le Chatelier's Principle can be used to predict the effect of changes in concentration, temperature, or pressure on a system at equilibrium. For the given reaction, when Br₂ is added, the system will respond by shifting the equilibrium to the left (towards reactants).