Solid ammonium hydrogen sulfide partially decomposes in a closed container according to the equilibrium
NH4HS(s) ⇌ NH3(g) + H2S(g)
Although the solid is present in excess, an inert gas was mistakenly added, raising the total pressure but not altering the amounts of NH3 and H2S present. Immediately after the addition, the partial pressures of NH3 and H2S were measured to be 0.210 atm and 0.180 atm, respectively. At 298 K the equilibrium constant in terms of pressure is Kp = 0.11.
Answer the questions below.
(a) Using the measured partial pressures, calculate the reaction quotient Qp for the gaseous species.
(b) Based on the calculated Qp and the given Kp, indicate the direction in which the reaction will proceed to re-establish equilibrium.
(c) Explain why the presence of excess solid ammonium hydrogen sulfide does not appear in the expression for Qp or Kp.