MDCAT Chemistry MCQ #2242

The equilibrium constant Kc for the reaction PCl5 ⇌ PCl3 + Cl2 has specific units. These units differ from the H2 + I2 ⇌ 2HI reaction because:

MDCAT Chemistry MCQ #2242

  1. Question 1

    Q1. The equilibrium constant Kc for the reaction PCl5 ⇌ PCl3 + Cl2 has specific units. These units differ from the H2 + I2 ⇌ 2HI reaction because:

    • A) Kc has no units for this reaction
    • B) The units are mol^2/dm^6
    • C) The units are mol/dm^3
    • D) The units are dm^3/mol

    Answer: The units are mol/dm^3

    Explanation: Units of Kc depend on the difference in moles (Δn); for PCl5 dissociation, Δn is 1, resulting in mol/dm3, unlike Δn=0 reactions.