At equilibrium, the partial pressure of HCl will be

Question

Quizplus · Accepted Answer

According to the given chemical equation, one mole of HCl reacts with one mole of O2 to form one mole of Cl2 and one mole of H2O. Therefore, if x moles of HCl reacts, x moles of O2 will also react, and x moles of Cl2 and H2O will be formed each. At equilibrium, the number of moles of HCl, Cl2, and H2O will be constant. Therefore, the sum of the partial pressures of HCl, Cl2, and H2O will be constant at equilibrium. Since Cl2 and H2O are gases, they will contribute to the total pressure of the system. However, HCl is not a gas at room temperature and will not contribute to the total pressure. Therefore, the partial pressure of HCl will be zero at equilibrium, and the sum of the partial pressures of Cl2 and H2O will be equal to the total pressure of the system. Since HCl is completely consumed in the reaction, its partial pressure will be less than 2 atm, which is the initial pressure of HCl in the system. Hence, the correct answer is B.

At Equilibrium, the Partial Pressure of HCl Will Be