Why are ketones more water-soluble than hydrocarbons?

1 Answer
Mar 6, 2018

Ketones form a partial negative charge, allowing them to create hydrogen bonds with water molecules.

Explanation:

Oxygen is more electronegative than carbon, meaning that it likes to "hog electrons" from the elements that it is bonded to (so long as they are not more electronegative than it). Electrons carry a negative charge, and since they spend more time around the most electronegative elements, these areas are considered to have a partial charge.

As you may have already noted, water, or H2O, contains an oxygen, which is significantly more electronegative than hydrogen. This means that the hydrogen elements in this molecule contain a partial positive charge (total charge of the molecule is conserved).

We know that opposite charges attract (insert eighth grade chemistry joke here), meaning that the ketone functional group will be attracted to the partially positive hydrogens in the water molecules.

This eventually results with the dissociation of the compounds that possess the ketone into water.