Consider the heterogeneous equilibrium in a closed containerNH4HS(s)  ⇌  NH3(g)  +   H2S(g)If more NH4HS is added to the equilibrium

NH4HS(s)  ⇌  NH3(g)  +   H2S(g)KP=NH3(g)  ×  H2S(g)Partial pressures of NH3 and H2O do not affect NH4HS(s) because NH4HS(s) is solid for solid active mass unity.