Concept:Vapor pressure is inversely proportional to the strength of intermolecular forces. Liquids with stronger intermolecular forces evaporate less readily, leading to lower vapor pressure.
Formula:$$ \text{Vapor Pressure} \propto \frac{1}{\text{IMF Strength}} $$
Solution:- Diethyl ether, chloroform, and carbon tetrachloride are highly volatile organics governed by relatively weak dipole-dipole or London dispersion forces.
- Water (\( \text{H}_2\text{O} \)) molecules form a strong, extensive network of hydrogen bonds.
- Because water's intermolecular forces are exceptionally strong, very few molecules escape into the vapor phase at \( 20^\circ\text{C} \), giving it the lowest vapor pressure of the group (approx \( 17.5 \text{ torr} \)).
Why other options are incorrect:Diethyl ether has the weakest forces and hence the
highest vapor pressure. Chloroform and \( \text{CCl}_4 \) are also much more volatile than water.
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