The presence of an unshared pair of electrons on nitrogen causes the angle C–N–E (where E is C or H) to be less than 109.5°; for example, it is 108° in trimethylamine.

Carboxylic acids are weaker than mineral acids but stronger than alcohols and many simple phenols. The pKₐ is approximately 16 for ethanol and 10 for phenol.

Aliphatic carboxylic acids with up to four carbon atoms are miscible in water due to hydrogen bond formation. However, solubility decreases with an increasing number of carbon atoms. Higher carboxylic acids become practically insoluble in water due to increased hydrophobic ...

Carboxylic acids have higher boiling points due to more extensive intermolecular hydrogen bonding. These bonds persist even in the vapour phase, with most carboxylic acids existing as dimers in the vapour phase or in aprotic solvents.

Aliphatic carboxylic acids up to nine carbon atoms are colourless liquids with unpleasant odours, while higher acids are wax-like solids with low volatility, resulting in practically odourless characteristics.