For the reaction Ag2S(s) ⇌ 2 Ag+ (aq) + S2- (aq), what happens to the equilibrium position if ammonium sulfate is added?
A) doubles
B) shifts to the left
C) does nothing
D) shifts to the right
E) halves
I don't think it will change the position at all although your prof may be expecting an answer of D. To make it shift to the left you must add Ag+ or S2- and neither is present in (NH4)2SO4. To shift to the right you must add something that reacts with either product but (NH4)2SO4 will do neither. Some may think adding (NH4)2SO4 will make it go to the right because of the formation of Ag2SO4; however, Ag2SO4 is more soluble than Ag2S (by far); for that reason the Ag2S solubility is the one that prevails.
To determine what happens to the equilibrium position when ammonium sulfate (NH4)2SO4 is added, we need to consider the ionic species involved.
Ammonium sulfate dissociates in solution to release ammonium ions (NH4+) and sulfate ions (SO4^2-). Since neither of these ions are involved in the original equilibrium reaction, their addition will not directly affect the equilibrium position.
Therefore, the answer is option C) does nothing.
To determine the effect of adding ammonium sulfate on the equilibrium position of the given reaction, we need to consider the reaction stoichiometry and the common ion effect.
In the equation: Ag2S(s) ⇌ 2 Ag+ (aq) + S2- (aq), Ag2S dissociates to form Ag+ and S2-. When ammonium sulfate (NH4)2SO4 is added, it dissociates into NH4+ and SO4^2- ions. The NH4+ ion is a common ion with Ag+, while the SO4^2- ion is a common ion with S2-.
The common ion effect states that if a solution already contains one of the ions involved in a reversible reaction, the equilibrium will shift to decrease the concentration of that ion.
In this case, adding ammonium sulfate introduces the common ions, NH4+ and SO4^2-, which are in equilibrium with Ag+ and S2- ions. Therefore, the equilibrium will shift to the left (option B) to reduce the concentration of NH4+, Ag+, and S2- ions.
Thus, the correct answer is B) shifts to the left.