Question

"Consider the reaction shown in Equation 1 at equilibrium. Would the concentration of [Cu(NH₃)₄]₂+ increase if the equilibrium were disturbed by adding hydrochloric acid?

A. Yes, because the equilibrium in Equation 1 would shift to the left
B. No, because the equilibrium in Equation 1 would shift to the left
C. Yes, because the equilibrium in Equation 1 would shift to the right
D. No, because the equilibrium in Equation 1 would shift to the right

[Cu(H₂O)₄]₂+(aq) + 4NH₃(aq) [Cu(NH-3)₄]₂+(aq) + 4H₂O(l)"

Answer 1

Adding HCl to the equilibrium system will cause a shift to the left due to Le Chatelier's Principle, leading to a decrease in the concentration of [Cu(NH3)4]2+, hence the correct answer is B.

Step-by-step explanation:

When hydrochloric acid (HCl) is added to the equilibrium described in Equation 1, the concentration of hydrogen ions ([H+]) increases. According to Le Chatelier's Principle, the system will try to counteract this increase by shifting the equilibrium in a way that consumes the excess hydrogen ions.

In this case, the added H+ ions will combine with the NH3 to form NH4+, thus reducing the free NH3 concentration. Equilibrium will then shift to the left to produce more NH3, which involves dissociation of [Cu(NH3)4]2+. Consequently, the concentration of [Cu(NH3)4]2+ will decrease, not increase. So the correct answer is B. No, because the equilibrium in Equation 1 would shift to the left.