Chapter 15, Problem 15.92QP

The decomposition of ammonium hydrogen sulfide

${\text{NH}}_{\text{4}}\text{HS}\left(s\right)\rightleftarrows {\text{NH}}_{\text{3}}\left(g\right)+{\text{H}}_{\text{2}}\text{S}\left(g\right)$

is an endothermic process. A 6.1589-g sample of the solid is placed in an evacuated 4.000-L vessel at exactly 24°C. After equilibrium has been established, the total pressure inside is 0.709 atm. Some solid NH₄HS remains in the vessel. (a) What is the K_p for the reaction? (b) What percentage of the solid has decomposed? (c) If the volume of the vessel were doubled at constant temperature, what would happen to the amount of solid in the vessel?