1. Physical state
Methanol is a gas at room temperature. Ethanol is a volatile liquid 294K. Other aldehyde and ketones are liquids or solids at room temperature.
Lower aldehydes have sharp pungent odors. As the size of the molecule increases, the odor becomes less pungent and more fragrant.Lower ketones are colorless liquids and have pleasant smell. The higher members are colorless solids. Aromatic ketones are usually solids with a pleasant smell.
Many naturally occurring aldehydes and ketones have been used in blending of perfumes and flavoring agents.2. Boiling points
Aldehydes and Ketones have relatively high boiling point as compared to hydrocarbons of comparable molecular masses. This is because the aldehydes and ketones contain polar carbonyl group and therefore have stronger intermolecular dipole dipole interactions between the opposite ends of C=O dipoles.
However, their boiling points are lower than those of alcohols of comparable molecular masses because unlike alcohols, they cannot form intermolecular hydrogen bonds.Ketones are relatively more polar then their corresponding isomeric aldehydes due to the presence of two electron repelling alkyl groups around the carbonyl carbon. Thus boiling points of ketones are slightly higher than those of isomeric aldehydes.
3. Solubility
Lower members of aldehydes and ketones (methanal, ethanal, propanone) are miscible with water because they form hydrogen bonds with water as shown.
As the size of the alkyl group increases the solubility decreases rapidly. It is because of the increase in the magnitude of non polar part in the molecule.
However lower as well as higher aldehydes and ketones are freely soluble in organic solvents such as benzene, ether, methanol etc.