A researcher is comparing the ability of two common laboratory solvents to dissolve molecular oxygen, O₂, at 25 °C and 1 atm.
• Solvent X: chloroform, CHCl₃ (dipole moment = 1.04 D)
• Solvent Y: acetonitrile, CH₃CN (dipole moment = 3.92 D)
Both solvents have comparable molar masses (≈ 119 g mol⁻¹ for CHCl₃, 41 g mol⁻¹ for CH₃CN) and are liquids at the stated conditions.
Answer the following questions about the factors that determine how strongly each solvent interacts with O₂.
(a) For each solvent–O₂ pair, identify the dominant intermolecular force that is responsible for attracting the non-polar O₂ molecules to the liquid phase.
(b) O₂ is experimentally found to be considerably more soluble in acetonitrile than in chloroform under the stated conditions. Explain this observation in terms of the molecular properties provided.
(c) Predict qualitatively how raising the temperature to 45 °C would affect the difference in solubility of O₂ between the two solvents. Justify your answer using intermolecular-force arguments.