TheChemistry of Soap
Final Project
What makes a good soap? How does its properties
make it an effective cleaning agent?
Final Project. Soap Chemistry. 1/24
Name ______________________
Period _____________________
Project Objectives:
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Students will understand what it means to “clean” something.
Students will understand the relationships among the chemical structure and chemical
properties of soap and its ability to clean.
Students will demonstrate an understanding of atoms; molecules; compounds; matter;
bonding: ionic bonds, covalent bonds; the periodic table; polarity; acids; bases; pH; and
basic chemical bonding.
Students will also understand how and why soap changes when you change the base and the
fat molecule used in the chemical reaction.
Students will also demonstrate a basic understanding of marketing design and their working
knowledge of chemistry, in a professional presentation.
Performance Tasks:
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The project is a three-part project that will require students to make predictions, collect and
analyze their data, draw conclusions and present their findings.
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Part 1: Making Soap
• Students will conduct research and use at least five different sources to write a
background for the project. This background should answer the guiding questions
included in the background section.
• Students will create a soap that fits their definition of a good soap and that works as
an effective cleaning agent.
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Part 2: Testing the Effectiveness
• Students will use the soap that they made from part 1 to test different properties of
their soap and compare their results to that of a popular moisturizing (Caress) and
antimicrobial soap (Dial).
- Test 1: Lathering Ability – Students will test to see how well their soap
lathers when compared to a good antimicrobial soap and
moisturizing soap.
- Test 2: Durability Test – Students will determine how durable their soap
is when compared to a good antimicrobial soap and moisturizing
soap.
- Test 3: Surfactant Test – Students will test to see how well their soap
dissolves oil when compared to a good antimicrobial soap and
moisturizing soap.
- Test 4: Stain Removal – Students will test to see how well their soap
cleans a series of four stains; dirt, hot sauce, charcoal, and oil
when compared to a good antimicrobial soap and moisturizing
soap.
Final Project. Soap Chemistry. 2/23
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- Test 5: pH – Students will measure the Ph of all three soaps to see if the
Ph played a role in their performance.
Based upon their understanding of an emulsifier and how it cleans dirt molecules,
students will create a hypothesis to explain how and why their soap should
effectively clean the stains.
Students will write individual procedures and execute their experiment
Students will collect data that will serve as evidence to “prove” that their soap is
effective. Evidence includes: color change; smell of cloth; texture of cloth, etc...
Students will then analyze their data, compare it to the data of other co-lab groups
and draw a conclusion based upon their findings.
Part 3: Roundtable
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Students will use their understanding of chemistry concepts to present their findings
in an entertaining marketing presentation.
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Students will consider the following questions when making their presentation: What
makes an exciting and interesting presentation? What characteristics should a good
product have? How will I explain my findings using scientific language while
linking different scientific concepts.
Final Project. Soap Chemistry. 3/24
Part 1. Making Our Soap
Aim: The aim of part 1 is to make a good soap
Instructions (the procedure can be altered to fit the specifications of your group):
A good soap is…
An effective soap is…
Materials:
1.
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6.
7.
Lard or some sort of fat (135ml).
53ml Sodium Hydroxide (NaOH)
250ml Glass and Plastic Beakers
Glass stirring rod.
Hot plate.
Mold for making soap bars.
98ml of H2O
Safety:
Gloves, lab coat and appropriate eyewear should be worn when handling the 6N NaOH. It should
be used in a well-ventilated area, preferably in a fume hood. DO NOT BREATHE THE FUMES.
Wash with vinegar should you get some on your skin (have some vinegar handy before starting
the experiment) - DO NOT wash with water!
Procedure:
1. Clean your work space.
2. Put goggles on.
3. In a glass beaker, place 53ml of NaOH into 97.5ml of H2O. Stir the mixture with a glass
stirring rod until it completely dissolves.
4. Place 135 ml of
(or any other fat, such as oil or butter) into the glass
beaker.
5. SLOWLY AND CAREFULLY sir the mixture.
***What happens when the NaOH is added to the fat? Record your results.
7. Add any additional ingredients to your soap once it has the consistency of pudding (Trace
Period).
12. Poor your soap mixture into the soap mold. The solid cake that forms is the soap (what’s left,
is glycerol).
Final Project. Soap Chemistry. 4/23
Observations:
What is fat?
What happens when NaOH is added to the fat?
How does the fat molecule change to create a soap molecule?
Final Project. Soap Chemistry. 5/24
Substance
Reason Added
(explain what each added substance does from a chemical perspective and an aesthetic perspective)
Final Project. Soap Chemistry. 6/23
Part 2. Testing its Effectiveness
Aim: The aim of this experiment is to test the effectiveness of your soap and explain
how its properties contribute to its abilities to clean, lather, last and….
Background:
1. What is Chemistry?
2. What do soap molecules look like?
a. How are the atoms inside of the soap arranged?
3. What ingredients do you need to add to soap in order to make it a good cleaning
soap? Why do these ingredients make it clean well? Explain how each
ingredient helps soap clean.
a. What happens to soap’s molecules when you put soap in water?
Final Project. Soap Chemistry. 7/24
b. Draw what happens below.
4. What ingredients do you need to add to soap in order to make it a good
moisturizer? Why do these ingredients make it moisturize well? Explain how
each ingredient helps soap moisturize.
5. What ingredients do you need to add to soap to make it durable? Why do these
ingredients make it durable? Explain how each ingredient helps soap’s
durability.
6. What is an emulsifier?
7. How does soap’s property as an emulsifier help it clean?
8. What is pH?
Final Project. Soap Chemistry. 8/23
a. What do soap manufacturers do in order to make sure that the pH of soap
isn’t too high?
9. How does the pH of soap affect its cleaning ability?
10. How does the pH of soap affect its ability to moisturize?
Final Project. Soap Chemistry. 9/24
Hypothesis:
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Final Project. Soap Chemistry. 10/23
Test 1: Lathering Ability
Materials:
Variables:
Constants:
Controls:
Independent:
Dependent:
Relationship between Independent and Dependent:
Procedure:
Final Project. Soap Chemistry. 11/24
Test 2: Durability Test
Materials:
Variables:
Constants:
Controls:
Independent:
Dependent:
Relationship between Independent and Dependent:
Procedure:
Final Project. Soap Chemistry. 12/23
Test 3: Surfactant Test
Materials:
Variables:
Constants:
Controls:
Independent:
Dependent:
Relationship between Independent and Dependent:
Procedure:
Final Project. Soap Chemistry. 13/24
Test 4: Stain Removal
Materials:
Variables:
Constants:
Controls:
Independent:
Dependent:
Relationship between Independent and Dependent:
Procedure:
Final Project. Soap Chemistry. 14/23
Test 5: pH
Materials:
Variables:
Constants:
Controls:
Independent:
Dependent:
Relationship between Independent and Dependent:
Procedure:
Final Project. Soap Chemistry. 15/24
Data:
Test 1: Lathering Ability (mL of bubbles)
Trial
Soap 1
Soap 2
Trial 1
Trial 2
Trial 3
Test 2: Durability (mass before being added to water and after being added to water)
Trial
Soap 1
Mass
before
Mass
after
Soap 2
Mass
before
Mass
after
Mass
before
Mass
after
Trial 1
Trial 2
Trial 3
Test 3: Surfactant Test (Dissolving of oil- drops of oil in soapy water)
Trial
Soap 1
Soap 2
Trial 1
Trial 2
Trial 3
Final Project. Soap Chemistry. 16/23
Test 4: Stain Removal (% removed)
Stain
Soap 1
Soap 2
Dirt
Oil
Hot Sauce
Charcoal
Draw what each of your stains looked like before treatment and after
treatment
Stain
Soap 1
Soap 2
Before
After
Before
After
Dirt
Oil
Hot Sauce
Charcoal
Final Project. Soap Chemistry. 17/24
Before
After
Test 5: pH (acidic or basic 0-14)
Soap 1
Soap 2
Homemade Soap
Additional Observations:
Final Project. Soap Chemistry. 18/23
Analysis:
Answer the following questions- using evidence from your calculations, sketches and tables to
support your answers.
1) How did the performance of your soap compare to that of the popular moisturizing and
antimicrobial soap in lathering ability?
Use evidence from your charts and graphs to support.
Final Project. Soap Chemistry. 19/23
2) How did the performance of your soap compare to that of the popular moisturizing and
antimicrobial soap in durability?
Use evidence from your charts and graphs to support.
3) How did the performance of your soap compare to that of the popular moisturizing and
antimicrobial soap in its ability to be a surfactant?
Use evidence from your charts and graphs to support.
Final Project. Soap Chemistry. 20/24
4) How did the performance of your soap compare to that of the popular moisturizing and
antimicrobial soap in its ability to clean a dirty stain?
Use evidence from your charts and graphs to support.
5) What was the final pH of each of the soaps (Soap 2, Soap 1 and your soap)?
6) Was the pH of any of the soaps out of the acceptable range of 7-8?
7) Explain how the pH might be connected to the durability, lathering ability, and cleaning
ability of the soap.
Use evidence from your charts and graphs to explain.
Final Project. Soap Chemistry. 21/23
8) Which commercial soap did your soap compare more closely to?
Use evidence from your charts and graphs to support.
Why do you think this happened?
9) Looking at your results, would you consider your soap a good moisturizing soap or a good
cleaning soap?
Why?
Use evidence from your charts and graphs to support.
Final Project. Soap Chemistry. 22/24
Conclusion:
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Final Project. Soap Chemistry. 23/23
Sources of Error:
Sources of information:
Final Project. Soap Chemistry. 24/24