A sealed, rigid reaction vessel at 500 K contains the following gaseous system at…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
A sealed, rigid reaction vessel at 500 K contains the following gaseous system at equilibrium:
2 SO₂(g) + O₂(g) ⇌ 2 SO₃(g)
The vessel has an internal volume of 3.00 L. The total pressure is suddenly increased three-fold by rapidly compressing the volume to 1.00 L while the temperature remains constant. No material is added or removed during the compression.
(a) Describe the predicted direction in which the equilibrium will shift as the system responds to the sudden compression. Justify your answer in terms of the relative amount of gaseous species on each side of the balanced equation.
(b) State whether the numerical value of the equilibrium constant Kp for this reaction will change as a result of the compression. Explain your reasoning.
(c) Qualitatively predict how the partial pressure of SO₃ will change from its pre-compression equilibrium value to its new post-compression equilibrium value. Include an explanation that links microscopic molecular behavior to macroscopic pressure changes.
(d) On appropriately labeled axes, sketch a qualitative graph of the partial pressure of SO₃ versus time beginning just before the compression and ending after the new equilibrium is reached. Clearly indicate the moments of compression, the transient response, and the final equilibrium region.