Physical properties due to hydrogen bonding

• Boiling points increase from methanol to pentan-1-ol.
• Solubility decreases from methanol to pentan-1-ol.
• The boiling and melting points increase as the molar mass increases because the number of van der Waals forces increases between molecules thus more energy is needed to overcome them.
• Solubility decreases as molar mass increases because the smaller the hydrocarbon chain, the larger the effect of the polar hydroxy group which can hydrogen bond with water molecules.
• The ability of an alcohol to hydrogen bond with water molecules decreases as the hydrocarbon chain increases.
• The boiling (and melting) points of alcohols are much higher than those of hydrocarbons of a similar molar mass.
• Alcohols have higher boiling points because the hydroxy group can hydrogen bond with the hydroxy group of neighbouring molecules which increases the strength of the intermolecular forces significantly thus more energy is needed to overcome them, whereas alkanes only have weak van der Waals forces between molecules.