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OBJECTIVE
After completing this experiment, the student should be able to:
1. Prepare a soap starting with olive oil
2. Examine the chemical properties of the soap that is made.
3. Understand what saponification means.
4. Understand how soap cleans.
INTRODUCTION
The name saponification literally means "soap making". The root word, "sapo", is Latin for soap.
The Italian word for soap is sapone. Soap making as an art has its origins in ancient Babylon
around 2500 - 2800 BC.
The oils used in modern handmade soap are carefully chosen by the soap maker for the character
they impart to the final soap. Coconut oil creates lots of glycerin, makes big bubbly lather, and is
very stable. Olive oil has natural antioxidants and its soap makes a creamier lather. Tallow, or
rendered beef fat, makes a white, stately bar that is firm and creates abundant lather. Many other
oils can be used, each one for a specific reason. Your soap maker will be glad to tell you which
oils are used to make her or his soap.
The alkali used in modern soap is either potassium hydroxide, which is used to make soft soap or
liquid soap because of its greater solubility, or sodium hydroxide, which is used to make bar
soap. The common term for the alkali became simply "lye", which curiously is not short for
alkali, but originated in the Anglo-Saxon language.
Soap made in cottages and on farms in earlier American times became known as "lye soap". That
term is now pejorative and derogatory and denotes a harsh soap that would irritate your skin. The
old soap got a bad name because it had an excessive amount of caustic. Weighing and measuring
techniques were crude, and knowledge of soap chemistry was elementary or non-existent.
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The true fact is that modern handcrafted soap, though necessarily made with lye to get true soap,
has no lye in the final product. It has all been reacted with the oils to form soap and glycerin.
A curious fact about modern soap is that most common soap found in the grocery store made in
mass-produced factories does have a small amount of excess alkali in it. Also, it has had all of its
naturally-occurring glycerin removed so it can be sold as a separate commodity. Why? Greater
profit. An important difference between most commercial soap and our Real Handmade soap is
that the glycerin is left in Real Handmade Soap and thus it retains its natural moisturizing
property.
MATERIALS AND APPARATUS
20 ml olive oil
30 ml of 95% ethanol
Beaker and glass-stirring rod
Hotplate
NaOH solution
3g of NaCl
100 ml of deionized water and ice
Buchner funnel and filter paper
SAFETY CONSIDERATION
1. All the instructions and modification of the experiment performed by student must be
authorized and supervised by the lab tutor.
2. Safety equipment such as goggles (eye), gloves (skin) and lab coat was used during the
experiment when dealing with highly concentration and/or toxic substance in order to
avoid any contact with skin or eyes.
3. All the equipment which was used must be washed cleanly by using distilled water before
and after using it in the experiment.
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PROCEDURE
1. About 20 ml olive oil was added to a 200 ml beaker and it was dissolved in a 30 ml of
95% ethanol.
2. When the olive oil was completely dissolve, put the beaker on the hot plat and the
temperature was maintained to about 85C. The flask was swirled to mix the solution.
Next, 20 ml of 50% NaOH solution was poured down the glass-stirring rod into the oil
solution. A small amount of the NaOH solution was trickled down the rod very slowly
and the stirring was stopped. Then, a little more NaOH solution was trickled in. The
mixture was stirred until it thickens.
3. A small watch glass was placed over the mouth of the flask to minimize evaporation of
the alcohol.4. The oil-alcoholic-NaOH solution was allowed to boil for at least 30 min. If an un-
dissolved fat was observed in the flask, a little more ethanol was added to the flask and
stir to dissolve the fat. The temperature was kept just hot enough to had controlled boiling
of the fat solution.
5. While the saponification proceeds, a salt solution was prepared by completely dissolving
30 g NaCl in 100 ml deionized water in a 250 ml beaker. After the salt completely
dissolves, about half of this salt solution was transferred to another beaker and both
beakers were placed on ice to cool down.
6. After 30 min, the fat solution was tested to see if saponification is complete by placing a
few drops of the solution in a test tube of deionized water. If fat droplets float to the top,
the saponification is not completed and it was allowed to boil for an additional 10 min.
7. When the saponification was completed, the hot reaction mixture was carefully poured
into one beaker of salt solution and stirred for a minute or two. The mixture was allowed
to cool for 24 hours before filtering.
8. A suction filtration with a Buchner funnel and filter paper was set up. The mixture from
step 7 was filtered and the soap was washed twice with cold salt water. Air was drawn
through the soap for a few minutes to remove most of the water.
9. The soap cake was removed from the Buchner funnel and it was saved for the following
tests.
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RESULT AND DISCUSSION
Results taken during conducting experiment:
Olive oil used
Mass is 17.2015g and the volume is 20 ml
NaCl used
Mass is 30.0355g
Calculation
1. Type of oil used: Olive Oil
2. Weight of oil taken: 17.2015g
3. Weight of NaOH used: 30.0355g
4. Weight of soap formed: 109.4g
5. Theoretical yield
Theoretical yield ( )
()
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6. Percentage of yield
According to the objective, I have understood the meaning of saponification and how soap clean.
Saponification is a chemical reaction that occurs when a vegetable oil or animal fat is mixed with
a strong alkali. The products of the reaction are two: soap and glycerin. Water is also present, but
it does not involve in the chemical reaction. The water is only a tool for the alkali to dilute,
which is otherwise a dry powder. Soap is able to be an excellent cleaner because of its ability to,
act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another
immiscible liquid. This means that while oil (which attracts dirt) doesn't naturally mix with
water, soap can suspend oil (dirt) in such a way that it can be removed.
CONCLUSION
All the objectives have been achieved. I have understood the meaning of saponification and how
soap has the cleaning ability.
LIMITATION
Do not pour the NaOH solution into the oil too quickly. Pouring the NaOH solution too
quickly will cause the oil to separate from the NaOH solution, and your final product will
be a failure.
Do not use high heat to boil or the alcohol will evaporate.
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REFERENCES
http://chemistry.about.com/od/cleanerchemistry/a/how-soap-cleans.htm
http://www.realhandmadesoap.com/folders/FAQ/what_is_saponification.htm
K. Schumann, K. Siekmann Soaps in Ullmanns Encyclopedia of Industrial Chemistry
2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a24_247
Thorsten Bartels et al. "Lubricants and Lubrication" in Ullmann's Encyclopedia of
Industrial Chemistry, 2005, Weinheim. doi:10.1002/14356007.a15 423
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