Consider the following compounds and their standard free energies of formation: Which of these liquids is (are)thermodynamically unstable?

Question

Consider the following compounds and their standard free energies of formation:  Which of these liquids is (are)thermodynamically unstable?

Quizplus · Accepted Answer

Thermodynamically unstable liquids have positive standard free energies of formation. Among the given compounds, the following have positive standard free energies of formation:
1) Water (H2O): -237.2 kJ/mol (negative, hence stable)
2) Hydrogen peroxide (H2O2): -136.2 kJ/mol (negative, hence stable)
3) Methanol (CH3OH): -162.3 kJ/mol (negative, hence stable)
4) Ethanol (C2H5OH): -277.6 kJ/mol (positive, hence unstable)
5) Acetone (CH3)2CO: -248.2 kJ/mol (negative, hence stable)

Therefore, the thermodynamically unstable liquids are 1, 3, and 5, and the answer is choice B.

Consider the Following Compounds and Their Standard Free Energies of Formation