Name: ________________________
Date: _____________________
Block: __________
Soap: Like Dissolves Like at Work
Engineering Design Process:
Identify the
Problem
Generate
Solutions
Test
Solutions
Analyze
Results
Request for Proposal:
Southridge High School Janitorial Services is accepting bids up until February 27th, 2015, to create, test, and evaluate
replacement soap for the restrooms. As employees of Skyhawk Engineering, Inc., you are being asked to develop a new
soap and to propose your product highlighting its strengths and weaknesses using several tests. In order for your plan to be
considered, it must adhere to the following criteria and constraints:
1) The soap must contain the following ingredients: plant fat, lye, salt, and
ethyl alcohol.
2) Each soap refill is currently purchased for $1.50. In order for your proposal
to be considered, you will need to keep your costs of making the soap below this
amount to allow for the maximum profit margin for the school.
3) The soap must emulsify oils and remove them from a surface to be
effective. This will be tested quantitatively by the ability to produce suds and
eliminate the presence of oil in a test tube and qualitatively by a wash test done by
your peers.
4) Additionally, quantitative tests will need to be done on the soap to measure
its pH level (acidity / alkalinity) to ensure it is safe to use on skin by being pH
balanced to a pH between 8 and 10.
Expense Report:
All soap recipes need 50 mL of ethyl alcohol. Since ethanol is partially polar and partially nonpolar, it will allow the ionic
hydroxide lye solution to mix with the nonpolar covalent oil to allow the saponification process to occur. This is a cost that
every group will incur.
50 mL ethyl alcohol : $0.50
The decisions about other ingredients will be left to each group. The choices are:
Oil (10 g)—you may use a combination
Lye 15 mL 6N
Salt (12 g)
Fragrance
Chemistry: Engineering Project Portfolio
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Canola @ $0.01/mL
Density = 0.92 g/mL
NaOH @ $0.05
NaCl @ $0.15
Eucalyptus @ $0.15/mL
Olive @ $0.02/mL
Density = 0.92 g/mL
KOH $0.07
Coconut @ $0.05/mL
Density = 0.93 g/mL
Lemon @ $0.20/mL
Jasmine @ $0.30/mL
1
Engineering Design Rubric:
Identifying and Defining a Problem to be Solved
HS-ETS1-1. Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for
societal needs and wants.
4—Advanced
3—Proficient
2—Nearing Proficent
1—Nonproficient
All of the previous plus:
•Scientific principles are
•Scientific principles are
•Problem/scientific
•Scientific principles are
related to investigation
somewhat related to
principles are unrelated to
related to investigation
explained simply.
investigation and/or lack
investigation or missing.
explained clearly.
•Problem is described.
depth.
•Criteria and constraints are
•Problem is detailed.
•Identifies major criteria
•Problem is partially
limited not addressed.
•Identifies all criteria and
and constraints.
described.
constraints.
•Identifies some criteria and
constraints.
Generating Possible Solutions
HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be
solved through engineering.
4—Advanced
3—Proficient
2— Nearing Proficent
1—Nonproficient
All of the previous plus:
•Describes two possible
•Describes only one
•No evidence present of
•Describes three or more
solutions.
solution.
comparing multiple
possible solutions.
•Evaluates the pros and
•Partially evaluates the pros solutions.
•Extensively evaluates the cons of each solution (two and cons of each solution
•Does not evaluate the pros
pros and cons of each
of each).
(one of each).
and cons of solution.
solution (three of each).
•Chooses one solution to
•Chooses the solution to test •Does not choose solution
•Articulates why criteria
test based on criteria and
partially based on criteria
based on criteria and
and constraints determine constraints.
and constraints.
constraints.
best choice to test.
Testing Solution(s) & Collecting Data
HS-ETS1-4. Use a computer simulation to model the impact of proposed solutions to a complex real-world problem with numerous criteria
and constraints on interactions within and between systems relevant to the problem.
4—Advanced
3—Proficient
2— Nearing Proficent
1—Nonproficient
All of the previous plus:
•Creates a prototype that
•Creates a prototype that
•Creates a prototype that
•Data is selective and
can be tested based on
can be tested partially based can be tested unrelated to
includes multiple types of
criteria and constraints.
on criteria and constraints.
criteria and constraints.
data for product
•Collects data that will lead •Collects insufficient data.
•Collects data unrelated to
evaluation.
to product evaluation.
•Data is not displayed in
product evaluation.
•Displays data in tables
tables and graphs for
If possible:
and graphs for analysis.
analysis or is incomplete.
•Modifies and retests
prototype.
•Displays data that shows
how modifications
changed the product.
Analyzing & Interpreting Results
HS-ETS1-3. Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of
constraints, including cost, safety, reliability, and aesthetics, as well as possible social, cultural, and environmental impacts.
4—Advanced
3—Proficient
2— Nearing Proficent
1—Nonproficient
All of the previous plus:
•Expenses and profit on
•Expenses and profit on
•Expenses and profit on
•Uses multiple types of
product are explained.
product are incomplete.
product are missing.
data to explain strengths,
•Makes a recommendation •Makes a recommendation
•Makes a disconnected
weaknesses, &
based on the success of
partially based on the
recommendation.
uncertainties of product.
the product.
success of the product.
•Limited or no evaluation of
•Recommendation is
•Uses data to identify
•Partially determines
strengths, weaknesses, &
related back to criteria and strengths, weaknesses, &
strengths, weaknesses, &
uncertainties of product.
constraints.
uncertainties of product.
uncertainties of product.
•Describes unrelated
•Modifications are based
•Describes one future
•Describes insufficient
modifications and
on data collected.
modification and limitation. modifications and limitations. limitations.
•Describes multiple future
modifications and
limitations.
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Engineering Portfolio for the Soap Project
Identify the Problem
What is the problem you are engineering a solution for?
What are the criteria (What must your soap do?) and constraints (restrictions) you face in creating the optimal soap?
Criteria
1)
2)
3)
Constraints
4)
Give examples of how the criteria or constraints might limit the design of your soap.
Draw a picture of a soap molecule and explain how it works to remove oils from your skin.
1)
Soap is a surfactant because
2)
Soap is created through a process called saponification, which
3)
The pH of soap should be between ________________
Because ________________________________________________________________________________
4)
*How does the type of oil used to make the soap contribute to its properties?
5)
*What is superfatting? What does it do to the properties of the bar soap?
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Generate Solutions:
Example Recipe:
Name: Sica’s Sweet Smelling Soap (SSSS)
Expenses:
ethyl alcohol:
Details
50 mL
Cost
$0.50
Oil
3 g coconut
$0.15
6 mL olive
$0.12
1 mL canola
$0.01
Lye
15 mL 6N KOH
$0.07
Fragrance
0.5 mL Lemon
$0.10
Total
$0.95/ soap refill
Profit
$0.55/ soap refill
Pros for Sica’s Sweet Smelling Soap

good balance of the cleansing ability of the
coconut and canola oils with the moisturizing
ability of the olive oil


Cons for Sica’s Sweet Smelling Soap

the olive oil is usually used to make very hard bar
soaps so in liquid form it might be too thick
using a mix of oils helps to keep the cost lower to
allow for a $0.30 profit/refill

this recipe might work better for a bar soap
the lemon fragrance will entice people to wash
more frequently because they will be left with
good smelling hands

additional water might need to be added in the
end to make it possible to be dilute enough to
come out of the dispensers

liquid soap will work best in the restrooms at
school because it will last longer and is more
sanitary

making a liquid soap does costs less than making
a bar soap ($0.07 instead of $0.20) because you
don’t need to “salt it out” at the end
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In your group, develop three detailed recipes to consider, including the total cost of each. Underneath, list the pros and cons
of each recipe:
1. Recipe “A” Name:__________________________________
Expenses:
ethyl alcohol:
Details
50 mL
Cost
$0.50
Oil
$
$
$
Lye
$
Salt
$
Fragrance
$
Total
$_______/ soap refill
Profit
$_______/ soap refill
Pros for ______________________ Recipe
Cons for ______________________ Recipe






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2. Recipe “B” Name:__________________________________
Expenses:
ethyl alcohol:
Details
50 mL
Cost
$0.50
Oil
$
$
$
Lye
$
Salt
$
Fragrance
$
Total
$_______/ soap refill
Profit
$_______/ soap refill
Pros for ______________________ Recipe
Cons for ______________________ Recipe






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3. Recipe “C” Name:__________________________________
Expenses:
ethyl alcohol:
Details
50 mL
Cost
$0.50
Oil
$
$
$
Lye
$
Salt
$
Fragrance
$
Total
$_______/ soap refill
Profit
$_______/ soap refill
Pros for ______________________ Recipe
Cons for ______________________ Recipe






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Look over your three recipes, including the pros and cons of each. In your group, decide which recipe you would like to
make.
In the space below, explain which recipe you will make (include the recipe name) and why (include why this is your best
recipe, based on the criteria and the constraints):
Example: The prototype recipe selected is “Sica’s Sweet Smelling Soap” because it has a mixture of fats, which will build a
good lather due to the coconut oil but will also moisturize hands due to the olive oil. The low cost of the olive and canola
oils ($0.02 and $0.01/mL) also allows for more profit. More coconut oil would be expensive to use with high cost ($0.05/g)
and would also leave hands too dry as it builds such a great lather that it could take the natural oils from the skin away as
well. Making liquid hand soap will be less expensive than bar soap, $0.07 for the KOH instead of $0.20 for the NaOH and
NaCl, because it eliminates the last step in the solid soap making stage of salting out. This reduces the cost by eliminating
the purchase of salt. The use of the ethyl alcohol will allow for the saponification process to happen faster so that the soap
can be made in one block. It will also need to be further diluted with water to be dispensed and this could incur additional
savings. The lemon fragrance is an added cost at $0.10, which is not necessary but will appeal to both men and women,
causing people to wash more frequently to have good smelling hands, thus keeping FGHS more clean. The total cost for
this soap is $0.95 per refill, which will allow a profit of $0.55 per refill.
The prototype recipe selected is ________________________________________________________________________
because __________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
_________________________________________________________________________________________________
________________________________________________________________________________________________ .
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Test Solutions:
Making Your Soap: (adapted from Mad Science: http://www.madsci.org/experiments/archive/854443814.Ch.html)
Recipe for ______________________________
Ingredients:
1. 250 mL beaker & stirring rod
4. 15 mL 6N __________ Hydroxide (__OH)
2. Bunsen burner & ring stand
5. 50 mL Ethanol
3. Fat Content (~ 10 g)
6. If making solid soap: 600 mL beaker
_____ g coconut
7. 300 mL saturated salt solution (NaCl)
_____ mL olive
8. Funnel & Filter Paper
_____ mL canola.
Procedure:
1. Place 10 grams of fat in a beaker.
2. SLOWLY AND CAREFULLY add 15 mL of your 6N lye/base to a liquid mixture of your fat(s).
3. Add 50 mL of ethanol and stir.
4. Take your first pH reading and record on page 8.
4. Gently heat this mixture under low heat, stirring with a glass-stirring rod until the lye has completely reacted with the fat
(about 20 to 30 minutes).
*You will see the soap mixture become denser as the fat reacts and turn into a jelly consistency. To test to see if the
saponification process is complete, you can take a couple of drops of your soap mixture and drop it into water. If you still
see droplets of oil, the process is not complete yet.
5. When saponification is complete, add 20 mL of distilled water to the soap solution and stir.
6. Take an additional pH reading and record on page 8.
7. If your pH is still higher than the optimum range, you will need to neutralize the excess base with citric acid. Add small
amount until the pH comes down to an acceptable range and record how much citric acid you needed to use on page 8.
8. Let this new mixture cool completely and add your fragrance if you are using any.
9. If you are making a solid soap, you will need to “salt out” your soap by dissolving 12 g of NaCl in 300 mL of water and
pour your soap mixture into the salt solution, not the other way around!
10. Set up a funnel and filter paper to separate your soap cake from the glycerin.
11. If making a liquid soap you may leave it in the beaker for further testing.
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Test Solutions (continued):
pH Test
You will need to continuously monitor the pH of the soap from the time that you add the lye to the time when it reaches
being pH balanced (at least a pH of 8) using the Vernier pH sensor and LabQuest:
1. Obtain your lye sample in a beaker from the instructor.
2. After you add the lye to the fat, stir for 5 seconds.
3. Using the pH probe, measure the pH of the lye and fat solution. (NB: Rinse the pH probe in tap water before and
after measuring the pH.)
pH:
Before
After
Saponification Saponification
After
Citric Acid
pH
Title:______________________________________________________
Graph your data.
*What should have happened to the pH during saponification?
*If you needed to neutralize your soap solution, how much citric acid did you have to use? What does this tell you about the
soap recipe we used?
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Emulsification Test
The emulsification test will help determine the effectiveness of your soap at removing oil.
Prepare a soap solution by dissolving about 1 g of your laboratory made soap in 60 mL (4 tablespoons) of warm water.
1. Place 4 drops of olive oil into each of six separate test tubes.
2. Add 5 mL of water to three tubes and 5 mL of soap solution to the other three. Take a “before picture” to show what
the test tubes looked like before emulsification.
3. Stopper and shake each tube vigorously for one minute. Take an “after” picture to show the amount of suds and the
degree of emulsification that happened in each tube. Attach the pictures of your test tubes to this packet.
4. Measure the degree of oil emulsification in each tube as indicated by the height of suds.
Data Table:
Test Tube
Number
Water-Bubble
Height (cm)
Soap waterBubble Height
(cm)
Title:_______________________________________
Average:
Graph your data.
*What does this graph tell you about how well your soap works?
*Rank the soaps in your class and predict which group’s soap will work the best to get hands clean.
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Lipstick Test
The lipstick test will allow us to view how effective your soap is at removing wax and oil.
1. Obtain two blank microscope slides and smear equal amounts of lipstick on each. Take a “before” photo to show
what each smear looked like before being soaked in a water or soap water solution.
2. Obtain two 250 mL beakers and put 125 mL of water in each.
3. Add 2 g of soap to one beaker and stir.
4. Place one slide in each beaker and let it soak for 15 min.
5. Remove slides and take an “after” picture to show how much lipstick is left on each slide.
Qualitative Lipstick Test Results for ___________________________ Soap:
Optimum
Score
Smell
3
Appearance
5
Oil removal
5
Ease of use
5
Marketability
5
Average Score
Judge 1
Judge 2
Judge 3
Judge 4
Average
4.6
Title:_______________________________________________
Which of the five factors evaluated by the lipstick tests do you believe to be the most important? _____________________
Why?
*Range of Average Wash Test Scores: ____________________
*Rank the soaps made in class, which ones worked the best? Does that agree or disagree with the emulsification tests?
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Analyze Results: Proposal Summary
Based on prototype development and prototype testing (pH, emulsification and wash test), Viking Engineers propose the
soap recipe described below for your consideration.
Recipe / Expenses / Potential Profit:
Recipe Proposed: __________________________________________________________________________________
Total
$_______/ soap refill
Profit
$_______/ soap refill
Test Results Summary (pH, emulsification, lipstick test):
Skyhawk Engineering Inc.’s _______________________ soap is the best replacement product for the restrooms because _
_________________________________________________________________________________________________
________________________________________________________________________________________________ .
The strengths of this soap are ________________________________________________________________________ .
The data (measurements, observations & lipstick test results) demonstrate these strengths because __________________
________________________________________________________________________________________________ .
The weaknesses of this soap are ______________________________________________________________________ .
The data (measurements, observations & lipstick test results) indicate the weaknesses of this design because___________
________________________________________________________________________________________________ .
Future modifications that might be made to the original design would be _________________________________________
_________________________________________________________________________________________________
because __________________________________________________________________________________________
________________________________________________________________________________________________ .
These modifications would make the product more successful because _________________________________________
________________________________________________________________________________________________ .
If the soap needs to be refilled each week at SRHS and there are 36 weeks in the school year, what is the total potential
profit that SRHS could realize and put towards other expenses?
_________________________________________________________________________________________________
________________________________________________________________________________________________ .
Considering the potential for high demand for this soap product, what limitations and challenges might you face in trying to
meet the needs of this order long term?
_________________________________________________________________________________________________
_________________________________________________________________________________________________
________________________________________________________________________________________________ .
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