For a generic gas-phase reaction at a particular temperature
CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)
Problem
For a generic gas-phase reaction
X(g)+2Y(g)⇌ZY2(g)Kc=K0 at a particular temperature,
a chemist constructs a new reaction sequence in three steps:
Step 1 Multiply the original reaction by 3.
Step 2 Reverse the equation obtained in Step 1.
Step 3 Add the reversed equation from Step 2 to the original (unscaled, unreversed) reaction to generate an overall reaction.
Answer the following questions.
(a) Write a balanced chemical equation for the overall reaction produced after all three steps are completed.
(b) Derive an algebraic expression for the equilibrium constant Koverall in terms of K0.
(c) Without substituting numbers, determine whether Koverall is greater than 1, less than 1, or equal to 1. Provide a qualitative justification based on the value of K0 relative to 1.
(d) Discuss how the sign and magnitude of ΔGoverall∘ compare with those of the original reaction. Your answer should reference thermodynamic relationships among K, ΔG∘, and the operations performed.