1. Higher Chemistry Detergents – Clean Chemistry
NEW LEARNING
Cleansing Action of Soaps – how do they work?
What are emulsifiers?
REVISION
Chemistry of fats and oils
Esters

2. Starter Task
S3 Revision

3. Starter Task
S3 Revision

4. Starter Task
S3 Revision

5. Lesson 1: Soap Production.
Today we will learn to
Make soap and explain the chemistry of their manufacture.
We will do this by
Making our own soap and explaining how they work.
We will have succeeded if
We can draw a soap molecule and label the hydrophilic and hydrophobic ends.

6. Making Soaps
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7. Making Soaps
Soaps are formed by the alkaline hydrolysis (breaking up) of fats and oils by sodium or potassium hydroxide by boiling under reflux conditions:

8. The Structure of Soaps
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9. polar, water-soluble, hydrophilic
The Structure of Soaps O O-
Na+
covalent hydrocarbon chain
non-polar, oil-soluble, hydrophobic
polar, water-soluble, hydrophilic
carboxylate head
In solution a soap molecule consists of a long non-polar hydrocarbon tail (e.g. C17H35-) and a polar head (-COO-).

10. The Structure of Soaps
The long covalent hydrocarbon chain gives rise to the hydrophobic (water hating) and oil-soluble (non-polar) properties of the soap molecule (represented in yellow). The charged carboxylate group (represented in blue) is attracted to water molecules (hydrophilic). In this way, soaps are composed of a hydrophilic head and a hydrophobic tail:

11. Recipe Time
Write a recipe for soap using ingredients you would have in the kitchen cupboard at home.
What would you need to do to make it saleable?

12. Starter Task
S3 Revision

13. Starter Task
S3 Revision

14. Lesson 2: How Soap Works Today we will learn to
Explain how soaps clean things!
We will do this by
Examining soap and using it to describe the link between bonding and solubility.
We will have succeeded if
We can draw a diagram to explain how soaps dissolve grease into water.

15. Cleansing Action of Soap

16. Cleansing Action of Soap

17. Cleansing Action of Soap
The hydrophobic tails dissolve into
the droplet of oil or grease. 
The hydrophilic heads are left to
face the surrounding water.
 This results in the formation of a
ball-like structure (a micelle).
The non-polar substances, such as
oil or grease, are held inside the ball and suspended in water, to be washed away.

18. Emulsions
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An emulsion contains small droplets of one liquid dispersed in another liquid. Emulsions in food are mixtures of oil and water. Examples of emulsions are mayonnaise and milk which have fat or oil droplets suspended in water and butter and margarine which have water droplets suspended in fat.
To prevent oil and water components separating into layers, a soap-like molecule known as an emulsifier is added. The emulsifier acts in a similar way to a soap.
DISCUSS
After discussion with your teacher and others can you explain what an emulsion is?
NOTES
Giving some examples, explain what an emulsion is.

19. Emulsions
An emulsion contains small droplets of one liquid dispersed in another liquid.
Emulsions in Food
Emulsions in food are mixtures of oil and water. To prevent oil and water components separating into layers, a soap-like molecule known as an emulsifier is added. Emulsifiers for use in food are commonly made by reacting edible oils with glycerol to form molecules in which either one or two fatty acid groups are linked to a glycerol backbone rather than the three normally found in edible oils. The one or two hydroxyl groups present in these molecules are hydrophilic whilst the fatty acid chains are hydrophobic.

20. Emulsions
p32

21. My Word!
Choose a word related to the lesson. You must stand up and point to someone in the class who must then give the meaning. That person then chooses the next person to pose a word.

22. Starter Task
S3 Revision

23. Starter Task
S3 Revision

24. Lesson 3: Testing Emulsifiers
Today we will learn to
Describe emulsification and give some examples of the uses of emulsifiers.
We will do this by
Testing different emulsifiers with vegetable oil.
We will have succeeded if
We can draw a diagram to explain how emulsifiers work.

25. Emulsions
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26. Emulsions
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27. Emulsions Activity 2.33 Testing Emulsifying Agents No risk Method:
Put 5cm3 of vegetable oil into a boiling tube.
Add 5cm3 of water.
Add 10 drops of emulsifier from a pipette.
Put in the stopper.
Invert the tube 10 times to mix the liquids.
Time how long it takes for a separate layer of oil to begin forming on the top of the mixture.
Repeat using different emulsifying agents.

28. Emulsions
p33

29. Consolidation Task Functional Families
You teacher may let you play this card game