A chemist has an equimolar mixture of two organic solids, naphthalene (C₁₀H₈) and benzoic acid (C₆H₅COOH), at 25 °C. Relevant data are provided.
• Vapor pressure at 25 °C: naphthalene = 0.030 torr; benzoic acid = 1.5 × 10⁻³ torr
• Molar mass: naphthalene = 128 g mol⁻¹; benzoic acid = 122 g mol⁻¹
• External pressure in the laboratory vacuum apparatus: 0.050 atm
(a) When the mixture is gently warmed under the reduced pressure of 0.050 atm, which component will enter the gas phase first? Use quantitative reasoning with the data above to support your choice.
(b) Compare the dominant intermolecular forces present in each solid and explain how those forces lead to the observed difference in volatility.
(c) Predict which component has the higher melting point at 1 atm and justify your answer using structural and thermodynamic arguments.