Which intermolecular forces are present in pure samples of both CH3CH2OH (ethanol) and CH3CH2NH2 (ethylamine)?

• A. London dispersion forces, dipole-dipole interactions, and hydrogen bonding
• B. Only hydrogen bonding
• C. Only dipole-dipole interactions and London dispersion forces
• D. Only London dispersion forces

Answer: (A)

Verified step by step guidance

1. Identify the types of intermolecular forces that can exist in molecules: London dispersion forces (present in all molecules), dipole-dipole interactions (present in polar molecules), and hydrogen bonding (a special, strong type of dipole-dipole interaction occurring when H is bonded to N, O, or F).
2. Examine the molecular structure of ethanol (CH3CH2OH): it contains an -OH group, which means it can form hydrogen bonds because hydrogen is directly bonded to oxygen.
3. Examine the molecular structure of ethylamine (CH3CH2NH2): it contains an -NH2 group, which means it can also form hydrogen bonds because hydrogen is directly bonded to nitrogen.
4. Since both ethanol and ethylamine are polar molecules, they exhibit dipole-dipole interactions in addition to London dispersion forces, which are present in all molecules regardless of polarity.
5. Conclude that both ethanol and ethylamine exhibit London dispersion forces, dipole-dipole interactions, and hydrogen bonding as their intermolecular forces.