5.1 g NH4SH is introduced in 3.0 L evacuated flask at 327oC. 30% of the solidNH4SH decomposed to NH3 and H2S as gases. The KP of the reaction at 327oC is
(R=0.082 L atm mol−1,
molar mass of S=32 g mol−1,
molar mass N=14 g mol−1.
0.242atm2
Moles of NH4SH=5.151=0.1 mol
NH4SH(s)⇌NH3(g)+H2S(g)
Initially 0.1 0 0
At equil 0.1(1−α)0.1α 0.1α
α=30%=0.3
So, number of moles equilibrium due to gaseous product
=0.1×0.3+0.1×0.3
=0.03+0.03
Now use PV = nRT
At equlibrium,
Ptotal×3lit=(0.03+0.03)×.082×600
Ptotal=0.984 atm
At equilibrium,
PNH3=PH2S=Ptotal2=0.492
Kp=PNH3×PH2S=0.492×0.492
Kp=0.242 atm2