If 8.0 g of NH4HS (s) is placed in a sealed vessel with a volume of 1.0 L and heated to 200 ∘C the reaction NH4HS (s) ⇌ NH3 (g) + H2S (g) will occur. When the system comes to equilibrium, some NH4HS (s) is still present. Which of the following changes will lead to a reduction in the amount of NH4HS (s) that is present, assuming in all cases that equilibrium is re-established following the change?

Adding more H2S (g) to the vessel

Adding more NH3 (g) to the vessel

Decreasing the volume of the vessel

Adding more NH4HS (s) to the vessel

Increasing the volume of the vessel

Increasing the volume of the vessel

Explanation:

By the Le Chatelier's principle, if a system in equilibrium suffer a variation that disturbs the equilibriu, the reaction shift in the way to minimize the pertubation and re-establish the equilibrium.

For a variation in pressure, when it increases, the reaction shift for the smallest of gas volume, and if decreases, the reaction will shift for the large gas volume. So, for the reaction given, the products have the large amount of gas, so by decreasing the pressure, more products will be formed, and the amount of NH₄HS will reduce. To decrease the pressure, we can increase the volume of the vessel: for the ideal gas equation (PV = nRT), pressure and volume are indirectly proportional.