explain why acetic acid (ch3cooh) forms dimers in the gas phase, but ethanol (ch3ch2oh) does not

1 answer

Acetic acid (CH3COOH) forms dimers in the gas phase due to the presence of hydrogen bonding between the molecules. The hydrogen atom in the hydroxyl group of one acetic acid molecule forms a hydrogen bond with the oxygen atom in the carbonyl group of another acetic acid molecule. This hydrogen bonding interaction stabilizes the dimer structure and allows for the formation of dimers in the gas phase.

On the other hand, ethanol (CH3CH2OH) does not form dimers in the gas phase because it lacks the necessary functional groups for hydrogen bonding to occur. While ethanol does contain a hydroxyl group, it does not have a carbonyl group like acetic acid which is essential for hydrogen bonding to take place. As a result, ethanol molecules do not form dimers in the gas phase and exist as single molecules.