The boiling points of methanol, water and dimethyl ether are respectively 65°C, 100°C and 34.5°C. Wh — Chemical Bonding Chemistry Question
Question
The boiling points of methanol, water and dimethyl ether are respectively 65°C, 100°C and 34.5°C. Which of the following best explains these wide variations in b.p.?
💡 Solution & Explanation
Step 1: Boiling point of a covalent molecular compound is mainly determined by the strength and extent of intermolecular forces, of which hydrogen bonding is exceptionally strong. Step 2: Water forms an extensive network of 4 hydrogen bonds per molecule; methanol forms an average of 2 hydrogen bonds per molecule; and diethyl ether cannot form intermolecular hydrogen bonds due to the absence of a hydrogen atom bonded to an electronegative atom (N, O, F). Step 3: Thus, the extent of hydrogen bonding decreases from water (highest b.p.) to methanol to diethyl ether (lowest b.p. / absent), which corresponds to option (b).