Oil and water are immiscible. Which is the most likely reason?

• A. Oil molecules have stronger dipole-dipole interactions than water molecules, causing them to separate.
• B. Both oil and water are polar substances, but their densities are too different to mix.
• C. Water molecules form strong hydrogen bonds, while oil molecules are nonpolar and cannot participate in hydrogen bonding.
• D. Oil molecules are ionic and water molecules are covalent, preventing them from mixing.

Answer: (C)

Verified step by step guidance

1. Understand the concept of miscibility: Two substances are miscible if they can mix in all proportions, forming a homogeneous solution. Immiscibility means they do not mix well and separate into layers.
2. Recall the polarity of molecules: Water is a polar molecule with a bent shape and a significant dipole moment, allowing it to form strong hydrogen bonds with other water molecules.
3. Consider the nature of oil molecules: Oils are generally nonpolar hydrocarbons, meaning they lack significant dipole moments and cannot form hydrogen bonds.
4. Apply the principle 'like dissolves like': Polar substances tend to mix with other polar substances due to similar intermolecular forces, while nonpolar substances mix with nonpolar substances. Since water is polar and oil is nonpolar, they do not mix well.
5. Conclude that the main reason for immiscibility is that water molecules form strong hydrogen bonds among themselves, while oil molecules are nonpolar and cannot participate in hydrogen bonding, leading to separation.