Intermolecular forces: boiling, viscosity and volatility
≈ 48 minIntermolecular forces: boiling, viscosity and volatility
Physical properties are evidence for the attractions between particles. A substance with stronger intermolecular forces usually needs more energy for molecules to escape into the gas phase, so it tends to have a higher boiling point and lower volatility. Viscosity describes resistance to flow; stronger attractions and larger, less mobile molecules can increase viscosity. Compare like with like: molar mass, molecular shape and polarity can all matter. A single property rarely proves the exact force type on its own, but it can support an explanation when combined with the molecular structure.
Work it through
At the same temperature, a liquid that evaporates quickly has a higher vapour pressure and is more volatile than a liquid with stronger attractions. If two molecules are similar in size but one can hydrogen bond, predict the hydrogen-bonding substance will usually have the higher boiling point and lower volatility. State 'usually' because experimental conditions and structure still matter.
Mastery target
Use structure and force type to compare boiling point, viscosity or volatility while naming the energy needed to separate particles.
Which liquid is expected to be more volatile at the same temperature?
Name the key chemistry term from Intermolecular forces: boiling, viscosity and volatility that best fits the explanation and visual model.
Why does water generally have a higher boiling point than methane?
Which statement corrects a common misunderstanding in Intermolecular forces: boiling, viscosity and volatility?