Question

Which of the following is most soluble in water?

`CH_3CH_2CH_2CH_2CH_2OH`
`CH_3CH_2CH_2COOH`
`CH_3CH_2CH_2CH_2NH_2`

Answer 1

All the molecules contain a polar group. However, the molecule that should be most soluble in water is propanoic acid. Why?

Explanation:

Butanoic acid has the shortest pendant alkyl chain. For this sole reason we would predict that it should give greater aqueous solubility. This is a prediction.

As a physical scientist, you should look up the literature to see if this prediction is true.