Chapter 4.8, Problem 1QQ

Interpretation Introduction

Interpretation:

Among the given statements, the one which is true when boiling points of ketones and aldehydes with other compounds of similar molecular mass has to be chosen.

Concept Introduction:

Carbonyl groups are the one which contain a double bond between carbon and oxygen atom.  Aldehydes and ketones possess this carbonyl functional group in it.  The structural representation of a carbonyl group can be given as shown below,

Aldehydes contain a carbonyl group that contains a hydrogen atom and a carbon atom bonded to it.  Aldehyde that has one and two carbon atoms are gas at room temperature.  The physical state of aldehyde that contains three carbon atoms to eleven carbon atoms that are not branched is liquid at room temperature.  Aldehydes that contain more than eleven carbon atoms are solid at room temperature.

Ketones contain a carbonyl group that contains two carbon atoms bonded to it.  For a compound to be ketone, a minimum of three carbon atom is required.  Ketones that contain three carbon atoms to eight carbon atoms which have the carbonyl group at the second carbon atom are liquid at room temperature.

Boiling point is the temperature at which the liquid state gets converted into gaseous state.  Aldehydes and ketones have their boiling points intermediate between the boiling points of alcohols and alkanes with similar molecular mass.  Due to the dipole‑dipole interaction, aldehydes and ketones have higher boiling point than alkanes.  Due to the absence of hydrogen bonding in aldehyde and ketones, they have lower boiling points than alcohols of similar molecular mass.