Question

are organic compounds soluble in organic solvents but not in water.

Answer 1

Lipids are organic compounds soluble in organic solvents but not in water.

Explanation:

Chemically, lipid is defined as organic compounds that are insoluble in water but soluble in organic solvents such as alcohol, chloroform and ether. Biologically, lipids are compounds that are composed of fatty acid or fatty acid derivatives soluble in organic solvents but insoluble in water.

Water is a polar molecule, with negatively and positively charged ends. This property of water makes it easy for it to interact with other polar molecules to form ionic bonds, dipole-dipole interactions and hydrogen bonds. Hence ionic compounds such as sodium chloride(Na⁺Cl^-) easily bind with water molecules and therefore they are readily soluble in water. Lipids, on the other hand, have non polar long hydrocarbon chains. The C-C and C-H bonds in this molecules are not charged and hence they can not readily bind to water molecules. Thus for water it is more energetically favorable to interact with other polar molecules, rather than non polar molecules such as lipids. Hence, lipids are water insoluble.

But lipids are readily soluble in organic solvents. Organic solvents are relatively less polar or even non polar as compared to water. Therefore, it becomes energetically favorable for those solvents to bind to lipid. Hence, this is why lipid is insoluble in water but soluble in organic solvents.