Organics Lab: Making soap: Saponification
Purpose: To experience a saponification reaction and produce a sample of “soap’. To test
the properties of the lab soap produced against a commercial soap.
This Lab will be done in pairs.
A) You and your partner will prepare the following for tomorrow’s lab:
Research saponification and select an acceptable “soap making” lab procedure to perform.
Bring in the “triglyceride” to be used in your selected lab. (You will be using a hotplate as a
heat source).
B) Lab Day-1: Perform your selected lab and produce your “soap” sample. You will need
to have it dry overnight.
C) Lab Day-2: You will now compare your soap sample against a commercial sample
on the following properties:
1)
2)
3)
4)
pH
Lathering Power
Hard Water effect
Cleaning properties
Part C. Comparison of the Properties of Soap with Commercial Soap.
C-1. pH
1. Prepare a 1% soap solution by dissolving about 0.5 g of both soaps in 50 mL
of deionized water. It may help to heat the water to get the soap to dissolve completely.
2. Use a glass stirring rod to place a drop of each soap solution on a piece of universal pH
paper to determine whether the solution is alkaline, neutral or acid. Record your
observation on your observations sheet.
C-2. Lathering Power
1. Add about 2 mL of deionized water to four large graduated test tubes.
2. Add an equal amount of soap solution to one test tube of water, cap, and shake
vigorously. This should give a permanent lather that lasts for at least 30sec. If the lather
doesn't last, add another 10 drops of soap solution and shake vigorously.
3. Do this for both samples and quantify the amount of lather by comparing volume of lather
to aqueous solution. Record the results on the report sheet.
C-3. Hard Water Effect
4. Add 2 mL of 5% calcium chloride solution to each of the two remaining test tubes of
water.
5. Add an equal amount of soap solution to one of the tubes containing calcium ion and
shake vigorously. Notice whether this solution forms a permanent lather and note
whether there is any flocculent precipitate in the tube. Does the precipitate float or sink?
6. Add an equal amount of detergent solution to the other tube containing Ca2+ ion and
shake vigorously to get a permanent lather. Does the lathering power of the detergent
differ from the soap when Ca2+ is present? Is there any precipitate in this solution?
Record the results on the report sheet.
C-4. Cleansing Power
1. Place a drop of used oil or fat, such as shortening, on four separate thin strips of filter
paper. Make sure the strips of filter paper will fit in the test tubes used in part C-2.
2. Place one filter paper with oil spot in the tube containing soap in water. Place another in
the tube containing detergent and water. Place a third strip in the tube containing soap in
calcium solution. Place the fourth strip of oily paper in the tube containing detergent and
calcium solution. Shake each one well and make sure the filter paper is immersed in the
solution.
3. After 2 min remove the filter paper and rinse with tap water. Did the oil get washed out
of the filter paper strip? You can discard the solutions in the sink. Throw the paper strips
in the trash can. Compare the cleaning power of soap vs detergent on the Report Sheet.
Part D: Lab Report:
Section
Inquiry
Application
Communication
I. Purpose (restate given)
II. Background and reaction of
Saponification
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III. Materials/Equipment for
your lab.***
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IV. Procedure (Past tense,
impersonal) ***
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V. Observations/Results
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(a) -2
(b) -2
(c) -2
(d) -2
VI. Analysis question (a), (b),
(c) (d)
VII. Error Analysis (analysis
question (e), (f))
(e)
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(f)
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X. Conclusion
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TOTAL MARKS
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*** Highlight any differences between your selected lab and the standard saponification lab in the
textbook. Pg 67.
Lab Report Due: ____________________________________________
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