Consider the gaseous equilibrium 2NO₂(g) ⇌ N₂O₄(g) at constant temperature
CHEMISTRY · Single correct · AP · Chemistry · Equilibrium · Equilibrium
Problem
Consider the gaseous equilibrium 2NO₂(g) ⇌ N₂O₄(g) at constant temperature. Once equilibrium is attained, which statement best accounts for the observation that the partial pressures of both gases remain constant over time even though their stoichiometric coefficients differ?
(a) At equilibrium the partial pressure of NO2 is exactly twice that of N2O4, matching the 2:1 stoichiometric ratio and preventing any further change.
(b) The forward and reverse reactions proceed at equal rates, so the amounts of NO2 and N2O4 do not change macroscopically.
(c) Since N2O4 is thermodynamically more stable, the forward reaction runs to completion and then stops, leaving the pressures of both gases unchanged.
(d) Because there are twice as many NO2 molecules in the balanced equation, their more frequent collisions automatically keep its partial pressure constant.