Dinitrogen tetroxide interconverts with nitrogen dioxide according to the balanced equation
N2O4(g)⇌2NO2(g)
At 298 K the equilibrium constant for this reaction is Kc=4.7×10−3. A closed 1.0 L flask at 298 K is charged with 1.0×10−3mol of N2O4(g) and 1.0×10−5mol of NO2(g), after which it is quickly sealed.
(a) Using only the numerical comparison between Qc and Kc (no detailed calculation required), identify whether the mixture is at equilibrium at the moment the flask is sealed.
(b) Explain, in terms of the relative amounts of reactants and products, the direction in which the reaction will proceed spontaneously to reach equilibrium.
(c) State the sign of ΔG for the reaction at the instant the flask is sealed, and justify your answer without performing any Gibbs free-energy calculations.
(d) The brown color observed in the flask is due to NO2(g). Describe qualitatively how the color intensity will change over time as the system moves toward equilibrium, and relate this observation to the microscopic changes in concentration.