Which of the following chemical properties allows soap to act as an emulsifier?

• A. It is highly acidic.
• B. It forms ionic bonds with water molecules.
• C. It is a strong oxidizing agent.
• D. It has both hydrophilic and hydrophobic regions.

Answer: (D)

Verified step by step guidance

1. Understand the role of soap as an emulsifier: An emulsifier is a substance that helps mix two immiscible liquids, such as oil and water, by stabilizing the mixture.
2. Recognize the structure of soap molecules: Soap molecules have two distinct regions—a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail.
3. Explain the hydrophilic region: The hydrophilic head of the soap molecule is polar and interacts with water molecules through hydrogen bonding or dipole-dipole interactions.
4. Explain the hydrophobic region: The hydrophobic tail of the soap molecule is nonpolar and interacts with nonpolar substances like oil through London dispersion forces.
5. Conclude how soap acts as an emulsifier: The dual nature of soap molecules allows them to surround oil droplets, with the hydrophobic tails embedding in the oil and the hydrophilic heads facing outward into the water, stabilizing the mixture and enabling the oil and water to mix.