Calcium carbonate thermally decomposes according to the balanced chemical equation…
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
Calcium carbonate thermally decomposes according to the balanced chemical equation
CaCO3(s) ⇌ CaO(s) + CO2(g)
The system is sealed in a rigid container at 900 K, where it is at equilibrium with an equilibrium constant Kp that is temperature-independent over a narrow temperature range around 900 K.
(1) Write the expression for the reaction quotient Qp for this equilibrium.
(2) The system is momentarily disturbed when a vacuum pump quickly removes some of the CO2(g), decreasing its partial pressure to a value below the equilibrium pressure. Describe qualitatively how this change affects the numerical value of Qp relative to Kp, and predict the direction in which the system will proceed to re-establish equilibrium. Justify your answer.
(3) Instead of removing CO2(g), a chemist adds additional powdered CaCO3(s) to the container while the system is at its original equilibrium state. Discuss whether this action changes the value of Qp. Predict and justify any shift (or lack thereof) in the position of equilibrium.