Final answer:
The equilibrium constant (Kp) for the decomposition of ammonium chloride into ammonia and hydrochloric acid at the given temperature is 3.0625 atm^2.
Step-by-step explanation:
To determine the value of the equilibrium constant (Kp) for the decomposition of ammonium chloride into ammonia and hydrochloric acid gases, we can use the given pressure of NH3 at equilibrium and infer that the pressure of HCl will be the same due to stoichiometry (since they are produced in a 1:1 ratio). Given the decomposition reaction NH4Cl(s) = NH3(g) + HCl(g), assume that the initial pressures of NH3 and HCl are both 0 (since NH4Cl is a solid), and at equilibrium the pressures are both 1.75 atm.
The equilibrium expression for Kp for this reaction is Kp = (PNH3)(PHCl) since there are no gaseous reactants. Plugging in the equilibrium pressures, Kp = (1.75 atm)(1.75 atm) = 3.0625 atm^2.