Surfactants and Emulsifiers (define chelating agent & preservatives) Practice Questions

Question 1

What does a chelating agent like Disodium EDTA do in cosmetic formulations?

Answer 1

Isolates metal ions to reduce product from oxidising = enhance stability, longer shelf life and improves foam performance in hard water

Question 2

Describe the function of Glycerin?

Answer 2

Humectant is polar and binds with water via hydrogen bonding with water molecules = retain moisture and hydration to skin/hair

Question 3

What is Cetrimonium Chloride and what is its charge?

Answer 3

A surfactant, cationic (positive charge)

Question 4

Why are preservatives in products, like Imidazolidinyl Urea and Sorbic Acid?

Answer 4

Acid: Prevent bacterial growth and product degradation = extends longer shelf life

Question 5

Surfactant mechanism of action?

Answer 5

• When added to water: Surfactant aligned themselves on surface water, with the hydrophilic head in water and hydrophobic tail in air/water (faces opposite way) = reduce surface tension
• Form Micelles: O/W. molecules form a spherical shape called micelle, trapping the oil (dirt and debris) in it with Hydrophilic head facing outwards and hydrophobic tail in face inwards with the oils
• Dispersion: rinsing away the oil, dirt and debris micelles with water

Question 6

What is a humectant and why is it important?

Answer 6

Humectants are polar and bind to the water molecules via forming hydrogen bonds = help retain moisture and hydration in the skin/hair

Question 7

What is a surfactant and what does it do?

Answer 7

Surfactants: Lower surface tension between two liquids, to remove dirt and oil

Question 8

Emulsifier mechanism of action?

Answer 8

Emulsifiers arrange themselves at the interface between the oil and water mixture, hydrophilic head face water and hydrophobic head face oil. They form multiple droplet/sphere like where it separates the oil and water (depends on o/w or w/o) = stabilises the dispersed droplets and prevent them from coalescing and colliding

Question 9

What type of product will have ___ chloride?

Answer 9

Surfactants

Question 10

What is the difference between cationic, anionic, non-ionic and amphoteric in suractant/emulsifiers?

Answer 10

• Cationic: Positive charge (good cat)
• Anionic: Negative charge
• Non-ionic: No charge
• Amphoteric: Charge changes depending on pH

Question 11

what is a emulsifier?

Answer 11

Emulsifier: when mixing 2 immiscible substances (oil and water) to form stable emulsion and prevent separation