A sample of solid NH 4HS is placed in a closed vessel and allowed to equilibrate. Calculate the equilibrium partial pressure (atm) of ammonia, assuming that some solid NH 4HS remains.

The answer to the question is

The equilibrium partial pressure (atm) of ammonia, assuming that some solid NH₄HS remains 0.26 atm.

Explanation:

To solve the question, we write out the chemical equation as follows

NH₄HS (s) ⇄ NH₃ (g) + H₂S (g)

From the above equation, it is observed that only the gaseous products contribute to the partial pressure

Kp = PNH₃·PH₂S where at Kp = 0.070 and PNH₃, PH₂S are the partial pressures of the gases

However since the number of moles of both gases are equal, therefore by Avogadro's law PNH₃ = PH₂S

Then PNH₃ = √ (0.07) = PH₂S = 0.2645 atm. ≅ 0.26 atm.