Question

Which is a more volatile liquid?
A. $C_2{H}_{5}OH$
B. $C{H}_{3}COOH$
C. $C_2{H}_{5}O{C}_2{H}_5$
D. $C_6{H}_6$

Answer 1

Hint: Volatile nature of liquids depends upon nature of liquid like hydrogen bonding, dipole interaction and dispersion forces.The liquids with higher vapour pressure are volatile .

Complete answer:
A volatile substance can be defined as a substance that evaporates readily at normal temperature or one that has a measurable vapor pressure.
Characteristics of volatility of a liquid:
Volatile liquids have low boiling points. A liquid with a low boiling point will begin to boil faster than liquid with higher boiling points. Much less energy (in the form of heat) required to break the intermolecular bonds of a volatile liquid than those of liquids having higher boiling points. In the presence of hydrogen bonding, a liquid decreases its volatile nature. This occurs due to hydrogen bonding, there is more association or forces of attraction between the molecules and their tendency to go into gaseous state decreases. Ethanol is less volatile in nature due to hydrogen bonding between the molecules of ethanol. In acetic acid, acetic acid is less volatile in nature due to hydrogen bonding. In ether, ether is less volatile in nature due to dipole-dipole attraction between the molecules. Ethanol, acetic acid and ether are the polar molecules. But $C_6{H}_6$will be more volatile since it has no hydrogen bonding but there are three different types of intermolecular forces, dipole interaction, hydrogen bonding, and dispersion forces. The only one that occurs with benzene is dispersion forces because it is a nonpolar molecule and the net dipole moment is zero. The other two forces in polar molecules.

Hence, the correct option is (D).

Note: Hydrogen bond is the electrostatic forces of attraction between covalently bonded $$H$$-atom of one molecule and the electronegative atom $$(F,N$$or$$O)$$ of the other molecules.Generally solids are less volatile than the liquids but there are some exceptions.The important factor that influences the substance volatile is the strength of attractions between its molecules.