Ammonium hydrogen sulphide dissociates as : NH4HS(s)⇌NH3(g) +H2S(g). Solid NH4HS is heated to a temperature TK in a closed vessel containing NH3 at 0.1 atm.  If the equilibrium pressure is 0.5 atm. The equilibrium constant Kp for the dissociation reaction is:

NH4HS(s)⇌NH3(g)         +        H2S(g)                                  0.1  atoms                 0  atoms                                  0.1fx atoms            x  atoms                                   0.1 + x atm          x atm Given: 0.1+x+x=0.5, x=0.2 atm; Kp==PNH3×pH2S=(0.1+x)×x=0.3×0.2  atm=0.06 atm2