Surfactants & Acid-Base Chemistry: Key Concepts and Applications

Surfactant

Surface Active Agent; a molecule that reduces surface tension or interfacial tension between two fluids, a gas and a liquid, a gas and a solid, or a liquid and a solid.

Hydrophilic head

Polar/charged region of a surfactant that bonds to water.

Hydrophobic tail

Non-polar hydrocarbon chain of a surfactant that bonds to oil/fats.

Micelles

Spheres formed by surfactants that trap oil/dirt inside and let water wash it away.

Oil-in-Water (O/W)

Type of micelle where oil droplets are dispersed in water (e.g. milk, lotion).

Water-in-Oil (W/O)

Type of micelle where water droplets are dispersed in oil (e.g. butter, creams).

Detergents

Surfactants that remove dirt/oil by surrounding and suspending particles in water.

Wetting Agents

Surfactants that reduce surface tension, allowing spreading and penetration.

Emulsifiers

Surfactants that force oil and water to mix.

Foaming Agents

Surfactants that trap gas in liquid to make foam.

Dispersants

Surfactants that break large particles into smaller ones and keep them suspended.

Non-ionic Surfactants

Surfactants with no charge, such as detergents and soaps; gentle and common.

Anionic Surfactants

Surfactants with a negative charge, such as sulfate detergents; strong cleaners.

Cationic Surfactants

Surfactants with a positive charge, such as fabric softeners; antimicrobial.

Zwitterionic/Amphoteric Surfactants

Surfactants that have both positive and negative charges, exhibiting pH-dependent behavior.

Arrhenius Acids

Substances that produce H⁺ ions in water.

Arrhenius Bases

Substances that produce OH⁻ ions in water.

Brønsted-Lowry Acids

Substances that act as proton donors.

Brønsted-Lowry Bases

Substances that act as proton acceptors.

Lewis Acids

Substances that act as electron pair acceptors.

Lewis Bases

Substances that act as electron pair donors.

pH Scale

A scale that measures acidity or basicity, where 0-7 is acidic, 7 is neutral, and 7-14 is basic.

Molarity (M)

The concentration measured in moles per liter.

Buffer

A solution that resists changes in pH.

Ka / pKa

Measures of acid dissociation or strength, where a lower pKa indicates a stronger acid.

Neutralization Reaction

A chemical reaction between an acid and a base that produces water and a salt.