The question
Name: ______________________ Date: ____________ Entropy of a gas that splits in two (4 points)
Particle view
N₂O₄ before and after
Colorless N₂O₄(g) breaks apart into brown NO₂(g) in a sealed container at constant temperature: N₂O₄(g) → 2 NO₂(g). ΔH° = +57.2 kJ/mol and ΔS° = +175.8 J/(mol·K).
Key: two joined dark circles, one N₂O₄ molecule; one dark circle, one NO₂ molecule.
(a) Using the particle diagram, justify the positive sign of ΔS° for the reaction. [1 point]
(b) Calculate ΔG° for the reaction at 298 K. [1 point]
(c) Calculate the temperature above which the reaction is thermodynamically favored. [1 point]
(d) A student concludes from part (b) that "no NO₂ is present in the container at 298 K." Explain why this conclusion is incorrect. [1 point]