Interfacial tension & Surfactants

What is interfacial tension?

• The force that acts at the interface between two immiscible liquids

• The force that acts at the interface between two miscible liquids

• The force that acts at the interface between a solid and a gas

• The force that acts at the interface between a liquid and a solid

Which unit is commonly used to express interfacial tension?

• Dyne/cm

• Newton

• Pascal

• Joule

What causes interfacial tension between two immiscible liquids?

• Imbalance of cohesive and adhesive forces

• Adhesive forces only

• Equal forces acting on both liquids

• Cohesive forces only

Which of the following factors does NOT affect interfacial tension?

• Nature of liquids

• Temperature

• Presence of surfactants

• Color of the liquids

What is a surfactant?

• A compound that increases surface tension

• A type of oil

• A compound that lowers surface tension

• A type of detergent only

Which part of a surfactant molecule is hydrophilic?

• Non-polar tail

• Hydrophobic group

• Polar head

• Hydrophobic alkyl chain

What type of surfactant carries a negative charge?

• Amphoteric surfactants

• Anionic surfactants

• Cationic surfactants

• Nonionic surfactants

Which of the following is an example of a nonionic surfactant?

• Cetyltrimethylammonium bromide

• Sodium lauryl sulfate

• Tween

• Cocamidopropyl betaine

What is the primary function of detergents?

• To keep particles evenly distributed

• To break down grease and dirt

• To stabilize emulsions

• To create foam

How do soaps and detergents remove dirt?

• By increasing water temperature

• By repelling dirt particles

• By dissolving dirt in water

• By forming micelles that trap dirt