Question

Which one of the following alcohols will be soluble in water? Which one of the following alcohols will be soluble in water? 2-pentanol 2-butanol 3-hexanol 2-propanol

Answer 1

We start answering this question using the concept ‘like dissolves like”.

Water is polar solvent and also alcohol. As this polarity depends on the side chain in the alcohol. More the carbon numbers are attached to the alcohol group in alcohol, less is the solubility of this alcohol in the water.

The solubility of alcohol in water is mainly decided by hydrogen bond formation between alcohol and water molecules.

This bond is the weak electrostatic attraction between H bonded to the more electronegative atom like N, O and F in one group of atom and N, O, F of other group of atoms.

Since alcohol has H bonded to oxygen and in water there is also H bonded to the oxygen the formation of hydrogen is possible in these molecules.

As we maintained at the beginning, the number of members of the carbon chain decide the solubility. 2-propanol has lowest number of carbon member and so less hydrophobic side chain is present in it.

Therefore, the solubility of 2-propanol is relative high as compare to others.

Hydrogen bonding between 2-propanol and water.

Therefore, the answer is 2-propanol.