Question

When oil and water are into the same vessel, two layers are observed with the less dense oil on top. These two liquids are said to be:

• A. hydrophilic
• B. hydrophobic
• C. insoluble
• D. immiscible

Answer 1

The correct option is D immiscible

When oil and water are into the same vessel, two layers are observed with the less dense oil on top. These two liquids are said to be immiscible. Liquids tend to be immiscible when the force of attraction between the molecules of the same liquid is greater than the force of attraction between the two different liquids.

Oils are typically nonpolar carbon-based molecules with high molecular weights. As a result, there are strong dispersion forces between the molecules in an oil.

Water molecules interact strongly by hydrogen bonding, so (if we consider water to be the solvent and oil the solute), we would say that there are strong solvent-solvent interactions (H bonding) and strong solute-solute interactions (dispersion forces between rather large molecules) but the solvent-solute interaction (dispersion interaction between water and 'oil') is sufficiently weak.