Consider the equilibrium reaction of nitrogen monoxide and oxygen forming nitrogen dioxide:
2NO(g)+O2(g)⇌2NO2(g)
At 350 K, Kp=5.9×103.
A 4.00 L rigid vessel at 350 K initially contains 0.600 mol NO, 0.200 mol O2, and 0.800 mol NO2. The mixture is allowed to reach equilibrium.
Two separate experiments are then carried out starting from this equilibrium mixture:
• Experiment I: An additional 0.300 mol of NO is injected; the volume and temperature remain unchanged.
• Experiment II: An inert gas is introduced until the total pressure doubles while the volume is kept constant.
Respond to the following prompts.
(a) For the original mixture before any disturbance, calculate the equilibrium partial pressures of all species.
(b) In Experiment I, determine the numerical value of Qp immediately after the NO injection and state the direction in which the reaction will proceed to re-establish equilibrium.
(c) For Experiment I, derive expressions for the new equilibrium partial pressures in terms of a single symbolic variable, then calculate their numerical values.
(d) In Experiment II, predict whether the equilibrium partial pressures of the reacting species will change. Support your prediction with quantitative or qualitative reasoning based on Qp and Kp.
(e) If the equilibrium composition in Experiment II were instead achieved by doubling the vessel volume (constant temperature, no inert gas added), qualitatively compare the shifts in equilibrium among the three scenarios: original, Experiment I, and this volume-doubling case.