Emulsifiers Learning objective to learn what an emulsifier

Emulsifiers Learning objective: to learn what an emulsifier is and to describe how it works

Outcomes * To remember foods (and other examples) of emulsions in everyday life (G) ** Compare a mixture of oil and water with and without an emulsifier (F/E) *** Explain how an emulsifier works (D/C)

What is this? How is it made?

Washing the pots • After we have cooked and eaten, our dirty pans and dishes often have lots of fat molecules. • What does washing up liquid do?

What does washing up liquid do? • Write down how you tested • Show your results in your book and say what washing up liquid does

Immiscible liquids • An immiscible liquid is a liquid where the two solutions have not mixed properly. Eg oil and water • The oil and water form layers

Why we use emulsifiers

emulsions • Oil and water do not mix • An emulsifier helps these to mix • Emulsifiers work because they have two parts to the molecule • A water loving part ( hydrophilic) • A water hating part (hydrophobic) • The water hating part likes oil

• There are two types of emulsions. • An oil-in-water emulsion contains small droplets of oil that are dispersed in water. • Alternatively, a water-in-oil emulsion has small droplets of water that are dispersed in an oil.

Emulsifier molecule • Hydrophilic • Bonds to water Hydrophobic Bonds to oil

How emulsifiers work Emulsifiers have molecules with two parts: A fat-loving or hydrophobic end A water-loving or hydrophilic end

How emulsifiers work ü The hydrophilic end bonds with water molecules. ü The hydrophobic end bonds with oil molecules ü In this way, the oil droplets stay mixed with the water.

Other emulsions • Some paints are emulsions • Milk is an emulsion • Mayonnaise is an emulsion of oil and vinegar with egg. Egg is the emulsifier

Mayonnaise • The egg yolk binds the oil and vinegar together to make a smooth substance • The egg yolk does not separate because the egg yolk has molecules in it that have both hydrophilic and hydrophobic groups • The hydrophobic tail is attracted to the oil whilst the head is attracted to the water and pulls the oil into the water

Emulsifiers • An emulsifier is a substance that causes immiscible liquids to mix Detergents are emulsifiers. They help when washing up as they allow the fat and water to mix.

Detergents The hydrophobic ends of the detergent start to dissolve in the grease. This leaves the hydrophilic end on the outside grease Cloth Eventually so many The grease now dissolves detergent molecules are in the water and floats stuck to the grease that away the outside of the grease is coved in water soluble ends grease Cloth

To finish off… • Oil slicks cause massive amounts of damage to the environment. • How could a detergent help to clean up an oil slick?

In your books • Draw a diagram to explain how emulsions work. Use the title “How emulsions work” A fat-loving or hydrophobic end A water-loving or hydrophilic end * To remember foods (and other examples) of emulsions in everyday life (G) ** Compare a mixture of oil and water with and without an emulsifier (F/E) *** Explain how an emulsifier works (D/C)

True or false? Oils dissolve in water. FALSE Oil will not dissolve in water – they will not mix. They are immiscible.

True or false? A substance which makes an oil mix with a water in small droplets is called an emulsifier. TRUE.

True or false? Emulsifiers work because their “head” dislikes water. FALSE Emulsifiers have a head which likes water.

True or false? Common examples of emulsions are milk AND mayonnaise. TRUE! Can you name any more?

True or false? Without emulsifiers, emulsions would be thick and smooth. FALSE! Without emulsifiers, emulsions would separate into blobs of oil floating in the water.