Question

Question: Predict the water solubility of each vitamin.

a.

b.

Short answer

Answer

1. Vitamin $B_3$is soluble in water due to the presence of polar groups in the molecule.
2. Vitamin $K_1$ is insoluble in water due to the presence of a hydrophobic hydrocarbon chain.

Step-by-step solution

Solubility of compounds in water

The solubility of compounds in water can be determined by the presence of hydrophilic groups in a compound. The greater the number of polar groups, the more will be the solubility of that compound.

The hydrocarbon chain in the molecules is hydrophobic. It is non-polar in nature, due to which it cannot dissolve in water.

The water solubility of each vitamin

Vitamin $B_3$is soluble in water. This is because of the presence of one carboxylic acid and one nitrogen atom in the molecule. These groups are polar in nature and make the molecule soluble in water.

Representation of polar groups

Vitamin $K_1$is insoluble in water, although it consists of two polar carbonyl groups. This molecule also consists of a non-polar hydrophobic hydrocarbon chain with more than 10 carbon atoms.

Repreparation of the hydrophobic hydrocarbon chain

Due to the presence of non-polar hydrocarbon parts, vitamin $K1$is insoluble in water.