Soap

Objectives

1.• Learn how to make soap

2.• Understand how soaps work

3.• Have a soap making competition

Making soaps

• Soaps are made from fatty acids and metallic ions such as sodium

• They are made by combining strong alkalis such as sodium or potassium hydroxide with oils or fats.

What is a lipid?

What is a fatty acid?Can you give them IUPAC names?

Chemical Reaction

• 2 stages• 1. fatty acids are separated from their glycerol

chain• 2. The alkali reacts with the fatty acid

producing a metalic carboxylate salt and water.

Diagram

How soaps work

2.

• The soap disocciates into sodium and carboxylate ions:• Which is positive and which negative? (see slide 7)

2.

• Carboxylates have hydrophobic and hydrophilic ends• What does this mean?• Which end is hydrophobic and which is hydrophilic?

3. • The hydrophilic ends come together to form clusters called micelles in water. • Soap is an emulsifying agent: what does this mean?

1.

How soaps work 2

5.

• The carboxylate chains form micelle balls with hydrophilic surfaces

• All have the same charge – what is it and what does this mean one micelle ball does to another?

6.

• Grease and oil attract dirt. Grease and oil are non- polar so they will not dissolve in what?

• But they will mix with the non-polar hydrophobic carbon chains of the carboxylate ions and micelles, so the grease and dirt is ………..

Lab session

• We will make soap in the lab using coconut oil.• But we could use other oils • We could add essential oils to provide scent• And colours• We could mould to different shapes

Competition

• Each table must design and develop their own soap. Consider these

• Brand name• Shape• Colour• Scent• Target market• Publicity materials• Cost to make and to be sold• Packaging

Rubricmarks Product quality

Marks x 2Costs Marketing strategy

1 Failed None None

2 Basic hard soap A cost given A target market identified

3 Some attempt to colour or scent and brand name

A price worked out Some advertising material

4 Good product with an element missing

Economics explained with some questions

Clear campaign strategy

5 Scented shaped coloured soap atractively packaged

Cost and price clearly explained

Effective marketing strategy supported by quality publicity