The value of \( K_{ p } \) for the equilibrium \( NH _{4} H S_{(s)} \rightleftharpoons NH _{3(g)}+ H _{2} S _{(g)} \) at a certain temperature and total 2 atm pressure at equilibrium will be _____\( atm ^{2} \)
We have given,
Total pressure at equilibrium = 2 atm.
Constant temperature = NH4HS(s) \(\rightleftharpoons\)NH3(g) + H2S(g)
Kp = \(\frac{P_{NH_3}\times P_{H_2S}}{P_{NH_4HS}}\)
∵ Partial pressure of solid substance is considered to be 1.
∴ Kp = \(P_{NH_3}\times P_{H_2S}\)
Kp = \((P_{NH_3})^2\)
(From the stoichiometry of reaction)
∵ Total pressure = 2 atm
∴ \(P_{NH_3}\) = \(\frac{2\,atm}{2}\) = 1 atm
\(P_{H_2S}\) = \(\frac{2\,atm}{2}\) = 1 atm
∴ Kp = (1)2
Kp = 1atm2
Hence, the equilibrium constant Kp = 1atm2