In a vessel of 1.0 L capacity, O₂(g) at 0.25 atm pressure and HCl(g) at 1.0 atm pressure are allowed — Chemical Equilibrium Chemistry Question
Question
In a vessel of 1.0 L capacity, O₂(g) at 0.25 atm pressure and HCl(g) at 1.0 atm pressure are allowed to react in presence of liquid water at 57°C.<br>4HCl(g) + O₂(g) ⇌ 2Cl₂(g) + 2H₂O(g); K_p = 5.0 × 10¹² atm⁻¹.<br>The volume occupied by liquid water is negligible but it is sufficient to achieve equilibrium with water vapour. The vapour pressure of water at 57°C is 0.4 atm. Select the correct statement(s) regarding the equilibrium mixture.
💡 Solution & Explanation
The presence of liquid water maintains the partial pressure of water vapour constant at 0.4 atm. Due to the very high K_p, the reaction almost reaches completion. 0.25 atm O₂ reacts with 1.0 atm HCl (stoichiometric) to form approx 0.5 atm Cl₂. Let remaining O₂ = x, HCl = 4x. K_p = (0.5)²(0.4)² / [(4x)⁴(x)] = 5 × 10¹². Solving gives x = 5.0 × 10⁻⁴ atm (P_O₂). P_HCl = 4x = 2.0 × 10⁻³ atm. Therefore, correct answer is A,B,C,D.