Question

In a closed system, how will a decrease in pressure affect the following reaction: N2O4(g) ⇌ 2NO2(g)?

Answer 1

Answer:

Answer 'A'

Explanation:

In general, if the Σmolar volumes(g) reactants ≠ Σmolar volumes(g) products, a change in atmospheric pressure will shift the reaction equilibrium. If the pressure is increased, the rxn will shift toward the LOWER molar volume side of the rxn or if the pressure is decreased the rxn will shift toward the HIGHER molar volume side. For the reaction N₂O₄(g) ⇄ 2NO₂(g), Vm(N₂O₄(g)) < Vm(NO₂(g)) so, a decrease in atmospheric pressure would shift rxn toward the NO₂(g) side of the equation increasing the moles of NO₂(g). Also, note that if the Σmolar volumes(g) reactants = Σmolar volumes(g) products, no shift in equilibrium will occur regardless of changes in atmospheric pressure.