NH4HS(s )<=>NH3(g)+ H2S(g) ∆H = +93 kilojoues
The equilibrium,above is established by placing solid NH4HS in an evacuated container at 25degreesC. At equilibrium, some solid NH4HS remains in the container. Predict and explain the following.
The effect on the equilibrium partial presure of NH3 gas when additional gas H2S is introduced into the container
if you add H2S, increasing its concentration, the reaction will go to the left to reduce the H2S concentration.
To predict and explain the effect on the equilibrium partial pressure of NH3 gas when additional gas H2S is introduced into the container, we need to first understand Le Chatelier's principle. According to this principle, if a stress is applied to a system at equilibrium, the system will shift in a way that reduces the stress.
In this case, adding additional gas H2S would increase the concentration of one of the product gases. Since the forward reaction (NH4HS → NH3 + H2S) consumes H2S and produces NH3, adding more H2S would cause the equilibrium to shift to the right in order to decrease the concentration of H2S and increase the concentration of NH3. This means that more NH3 gas would be formed as a result.
Therefore, the introduction of additional gas H2S would increase the equilibrium partial pressure of NH3 gas in the container.