Physical Properties of Alcohols
Explaining the boiling points, solubility in water, and the role of intermolecular hydrogen bonding in determining these properties of alcohols.
What is Physical Properties of Alcohols?
An intermolecular force of attraction that exists between a hydrogen atom bonded to a highly electronegative atom (like O, N, F) and another electronegative atom with a lone pair of electrons.
Key points
- Explain the reasons behind the boiling points of alcohols.
- Describe the solubility of alcohols in water.
- Relate hydrogen bonding to the physical properties of alcohols.
- Compare the physical properties of alcohols with those of alkanes.
Common exam trap
Forgetting that hydrogen bonding is the primary reason for higher boiling points compared to alkanes.
Definitions
- Term
Hydrogen Bonding
- Meaning
An intermolecular force of attraction that exists between a hydrogen atom bonded to a highly electronegative atom (like O, N, F) and another electronegative atom with a lone pair of electrons.
- Term
Hydrophobic Effect
- Meaning
The observed tendency of nonpolar substances to aggregate in an aqueous solution and exclude water molecules.
Learning objectives
Explain the reasons behind the boiling points of alcohols.
Describe the solubility of alcohols in water.
Relate hydrogen bonding to the physical properties of alcohols.
Compare the physical properties of alcohols with those of alkanes.
Prerequisites
Structure of Alcohols
Polarity and Electronegativity
Intermolecular Forces (Hydrogen Bonding, van der Waals forces)
Molecular Weight and its relation to physical properties
Common mistakes
Forgetting that hydrogen bonding is the primary reason for higher boiling points compared to alkanes.
Assuming solubility remains constant with increasing molecular weight.
Confusing intramolecular and intermolecular hydrogen bonding.
Not considering the hydrophobic effect of the alkyl chain on solubility.
Keywords
Alcohols
Physical Properties
Boiling Point
Solubility
Hydrogen Bonding
Hydrophobic Effect
Polarity
Intermolecular Forces
Practice preview
Why is ethanol soluble in water?…
easy
Which of the following alcohols has the highest boiling point?…
easy
Which of the following alcohols will be LEAST soluble in water?…
medium