Consider the following compounds and their standard free energies of formation: $\begin{array}{|c|c|c|c|c|}
\hline 1&2&3&4&5\
\hline \begin{array}{c}
\mathrm{C}_{6} \mathrm{H}_{12}(\mathrm{l}) \
\text { cyclohexane }
\end{array} & \begin{array}{c}
\mathrm{CH}_{3} \mathrm{OH}(\mathrm{l}) \
\text { methanol }
\end{array} & \begin{array}{c}
\mathrm{N}_{2} \mathrm{H}_{4}(\mathrm{l}) \
\text { hydrazine }
\end{array} & \begin{array}{c}
\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{l}) \
\text { hydrogen peroxide }
\end{array} & \begin{array}{c}
\mathrm{CS}_{2}(\mathrm{l}) \
\text { carbon disulfide }
\end{array} \
\hline+6.4 \mathrm{~kJ} \cdot \mathrm{mol}^{-1} & -166 \mathrm{~kJ} \cdot \mathrm{mol}^{-1} & +149 \mathrm{~kJ} \cdot \mathrm{mol}^{-1} & -120 \mathrm{~kJ} \cdot \mathrm{mol}^{-1} & +65.3 \mathrm{~kJ} \cdot \mathrm{mol}^{-1} \
\hline
\end{array}$ Which of these liquids is (are)Thermodynamically unstable?

Question

Quizplus · Accepted Answer

Thermodynamic stability is often indicated by a negative standard free energy of formation, implying that the compound is stable under standard conditions. Compounds 1, 3, and 5 have positive standard free energies of formation, indicating that they are thermodynamically unstable under standard conditions.

Consider the Following Compounds and Their Standard Free Energies of Formation