Question

For which of the following parameters the structural isomers $ {{C}_{2}}{{H}_{5}}OH $ and $ C{{H}_{3}}OC{{H}_{3}} $ would be expected to have the same values? (Assume ideal behaviour)

• A. Heat of vaporization
• B. Vapour pressure at the same temperature
• C. Boiling points
• D. Gaseous densities at the same temperature and pressure

Answer 1

Answer: (D)

In $ C{{H}_{3}}C{{H}_{2}}OH, $ there is intermolecular H-bonding while it is absent in isomeric ether $ C{{H}_{3}}OC{{H}_{3}} $ Larger heat is required to vaporise $ C{{H}_{3}}C{{H}_{2}}OH $ as compared to $ C{{H}_{3}}OC{{H}_{3}}, $ thus is incorrect. $ C{{H}_{3}}C{{H}_{2}}OH $ is less volatile than $ C{{H}_{3}}OC{{H}_{3}}, $ thus vapour pressures are different, thus is incorrect. bp of $ C{{H}_{3}}C{{H}_{2}}OH>C{{H}_{3}}OC{{H}_{3}}, $ thus is incorrect. $ Density=\frac{mass}{volume}, $ due to ideal behaviour at a given temperature and pressure volume and molar mass are same. Hence, they have same vapour density.