Q. For the reaction, CH₄(g) + 2O₂(g) ⇌ CO₂(g) + 2H₂O(l), ΔrH = −170.8 kJ mol⁻¹ Which of the following statements is not true ?
A) At equilibrium, the concentrations of CO₂(g) and H₂O(l) are not equal
B) The equilibrium constant for the reaction is given by Kp = [CO₂]/[CH₄][O₂]
C) Addition of CH₄(g) or O₂(g) at equilibrium will cause a shift to the right
D) The reaction is exothermic
Explanation
[Solution from source] The correct expression excludes the pure liquid H₂O and raises O₂ to its coefficient: Kp = p(CO₂)/[p(CH₄)·p(O₂)²]. The given Kp = [CO₂]/[CH₄][O₂] omits the square on O₂, so it is the false statement. Adding a reactant shifts the equilibrium right, and a negative ΔrH means exothermic. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.