Question

Is toluene soluble in water?

Answer 1

Toluene is an aromatic compound in which a methyl group is present on the benzene ring. In water, there is strong hydrogen bonding because oxygen and hydrogen can form a hydrogen bond, so the incoming molecules must form a stronger bond than the already existing hydrogen bond.

Complete step-by-step answer: Toluene is an aromatic compound in which a methyl group is present on the benzene ring and its molecular formula is ${{C}_{7}}{{H}_{8}}$. The structure of toluene is given below:

It is an aromatic hydrocarbon because there is no functional group in toluene. The molecular mass of toluene is 92.141 g /mol. Since it is an aromatic compound, its odor is sweet and benzene-like. It is a colorless liquid and has a density of 0.87 g /mL.
Its solubility in water is very less or negligible and it is equal to 0.52 g /L at ${{20}^{\circ }}C$ which means in one liter of water only 0.52 grams of toluene is soluble. This can be explained as, the water is made up of hydrogen and oxygen, and we know that oxygen is an electronegative atom so, there will be bonding between the molecules of water. Since there is no electronegative atom in toluene, the bonding formed between toluene and water is a van der Waal interaction which is a weaker interaction than the hydrogen bonding. So this weak van der Waal interaction cannot compensate for the strong already existing hydrogen bonding in the water.
Hence, toluene is not soluble in water.

Note: The boiling and melting points of toluene are 384 K and 178 K respectively. Alcohols are carboxylic acids and are quite soluble in water because both of them contain oxygen atoms for making hydrogen bonding.