MDCAT Chemistry MCQ #2229

The decomposition of calcium carbonate (CaCO3 ⇌ CaO + CO2) is a heterogeneous equilibrium. This differs from the homogeneous N2O4 ⇌ 2NO2 system because:

MDCAT Chemistry MCQ #2229

  1. Question 1

    Q1. The decomposition of calcium carbonate (CaCO3 ⇌ CaO + CO2) is a heterogeneous equilibrium. This differs from the homogeneous N2O4 ⇌ 2NO2 system because:

    • A) The concentration of CaCO3 is doubled in the expression
    • B) Pure solids like CaCO3 are omitted from the Kc expression
    • C) The pressure of solids affects the equilibrium position
    • D) Only the liquid phase is considered in the calculation

    Answer: Pure solids like CaCO3 are omitted from the Kc expression

    Explanation: In heterogeneous equilibria, the concentration of pure solids is taken as unity, unlike homogeneous systems where all species appear in Kc.