Chapter 22, Problem 11RQ

Why are low formula mass alcohols soluble in water?

To determine

The reason for solubility of low-formula-mass alcohols in water.

Answer to Problem 11RQ

Low-formula-mass alcohols are soluble in water due to the polarity of the bond between hydrogen and oxygen.

Explanation of Solution

Hydroxyl group present in the alcohol is capable of making hydrogen bonds with water molecules. This is due to the polarity of the bond between the hydrogen atom and the oxygen atom of the alcohols. A low-formula-mass alcohol have a small hydrocarbon chain which is hydrophobic in nature. Due to this hydrogen bonding tendency of alcohol is more. As a result, low-formula-mass alcohols are soluble in water. With the increment in formula mass there is increase of carbon chain i.e. the hydrophobic part which is water repelling. Hence, the solubility of higher formula mass alcohols is lower in water as compared to the low formula mass alcohols.

Conclusion:

Therefore, due to polarity of bond between the bond between hydrogen and oxygen and a smaller number of carbon chain the low-formula-mass alcohols are soluble in water