Concept:Vapor pressure is inversely related to the strength of intermolecular forces. Weaker forces allow more molecules to escape into the vapor phase.
Formula:$$ \text{V.P.} \propto \frac{1}{\text{IMF Strength}} $$
Solution:- Ethylene glycol has two \( \text{-OH} \) groups, allowing for massive hydrogen bonding (lowest VP).
- Water has very strong hydrogen bonding networks.
- Ethanol has a single \( \text{-OH} \) group, allowing moderate hydrogen bonding.
- Diethyl ether (\( \text{CH}_3\text{CH}_2\text{-O-CH}_2\text{CH}_3 \)) cannot form hydrogen bonds with itself; it only has weak dipole-dipole and London dispersion forces. Therefore, it is highly volatile and exerts the highest vapor pressure.
Why other options are incorrect:The other molecules all possess \( \text{O-H} \) bonds capable of strong intermolecular hydrogen bonding, restricting their volatility.
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