First exercise
The History of Tripoli Soap
It was at the end of the 15th century that the governor of Tripoli Youssef Beksayfa
established Khan Al Saboun. This souk was completed at the beginning of the 16th
century. This time corresponds to the last days of Mamluk rule.
Soap making was very popular in Tripoli, so much that the Souk became a trading center
where the soap was made and sold. It is even in these places that the Tripolitan traders
began to export their soaps to Europe, where they began to offer these scented soaps as a
gift. Thus, this craft has grown in Tripoli. With the demand constantly increasing, the
craftsmen began to consider this work as a true art, and sought to satisfy the amateurs of
their products by manufacturing a high quality soap, always more effective and of various
forms. This is how the Arab and Western countries began to import the Tripoli soap. At
the beginning of the 19th century, Europeans began to produce soap by automated and
chemical processes, thus competing with the Tripoli market. At that time, the local
producers, and to produce their soap, also began to use the machines, which made it
possible to manufacture their products at a lower cost, with a better yield. Since then,
traditional soap production has gradually decreased in favor of mechanical processes. But
some craftsmen continue to make this soap in the manner of the past.
How is soap made in Tripoli?
The raw material used for these soaps is olive oil with sodium hydroxide (Katroun).
Honey, essential oils and natural aromatic raw materials are also added to the
composition: flowers, petals, herbs ... The soaps are dried in the sun, in a very dry air, this
allows the evaporation of the water that has served for mixing and mixing the different
ingredients. This drying lasts about 3 months. As the water evaporates, a thin white film
forms on the surface of the soap: it is the soda resulting from sea salts. The craftsman
then proceeds to a careful brushing with the until all traces of powder have been
removed.
Questions
1. Referring to the text:
1.1- List the substances necessary for the manufacture of the soap.
1.2- List the additives added to the soap.
1.3- Indicate the reason why one must wait 3 months before using the soap.
1.4-How to eliminate the white powder that forms on the soap.
1.5-Explain how the yield of soap making has been increased.
2. Tripoli soap contains no synthetic products such as anti-scale agents.
2.1-Define hard water.
2.2-Write the chemical equation of
i. the saponification reaction.
ii. the reaction of calcium ions in water with soaps.
iii. the formation of triglyceride.
3. Explain why the use of hard water with soaps can make it hard to clean clothes
4. List three disadvantages of using soaps with hard water.
Second exercise
fatty substances
Fats represent more or less 2/3 of the raw materials in a soap factory. In theory, any nonvolatile oil or fat can be used, but in practice their number is greatly reduced due to
economic, technical and chemical reasons. These fatty substances are saturated or
unsaturated.
Based on the composition of fatty acids, we distinguish several categories of fatty
substances such as:
- Nut oils: The two oils in this category that are important for soap are coconut
(coconut) and palm kernel oil. These oils have the specific characteristic that they
easily produce foam. However, these two oils, but especially coconut oil, make
the skin rough. So these oils are most often mixed with other oils but in limited
quantities (10 to 20%), on the one hand to ensure the foam and on the other hand
to not harm the skin. Soaps made from pure coconut oil are not very stable in
storage and have a tendency to deform.
-
Palmitic oil: Its price is higher than that of palm oil because the manual
extraction is difficult and long and the oil does not keep long. Palm oil is less
harsh on the skin than coconut oil. The soap made from pure palm kernel oil is
very hard and stable in storage. However, palm kernel oil is most often mixed
with palm oil, produced from the same tree.
The following document represents the structural formula of palmitic acid:
Given:
C=12g.mol-1; H=1g.mol-1; O=16g.mol-1
Questions
1. Referring to the text:
1.1. Give an advantage and a disadvantage of the nut oils.
1.2. Indicate why some oils are mixed.
2. Distinguish between oils and fats from a structural and physical point of view.
3. Specify whether palmitic acid is saturated or unsaturated.
4. Write its molecular formula; then give its symbolic representation.(x:y)
5. Calculate the molecular mass of palmitic acid
6. An alcohol X of molecular formula CxH10O has a molar mass of 76 g.mol-1.
i.
Show that x=4
ii.
Write the esterification reaction between X and palmitic acid.