chemistry

1. A. Title Experiment : Preparation of Soap
B. Day/Date of Experiment : Tuesday/ November, 4th 2014
C. Done : Tuesday/ November, 4th 2014
D. Purpose :
1. Making procedure of soap preparation
2. Predicting reaction of soap preparation
3. Explaining the differences of soap product using basic solution NaOH
and KOH
4. Making soap emulsion
5. Explaining the process of formation of soap emulsion with oils.
6. Determining the quality of oils based on peroxide number.
E. Basic Theory
Soaps and detergents are essential to personal and public health. They safely
remove germs, soils and other contaminants and help us to stay healthy and
make our surroundings more pleasant. Soaps are made from fats and oils
or their fatty acids.
Fatty acids are merely
carboxylic acids consisting of a
long hydrocarbon chain at one
end and a carboxyl group (-
COOH) at the other end. They
are generally represented as
RCOOH. They are an important
component of plants, animals and other microorganisms. They are found in
various parts of the body, such as cell membranes, the nervous system and
as lung surfactant. There are two groups of fatty acids: saturated fatty acids
and unsaturated fatty acids.
Saturated fatty acids:
Fatty acids contain carbon-carbon single bonds called saturated fatty acids.
Examples: stearic acid (C17H35COOH) & palmitic acid (C15H31COOH)

2. Unsaturated fatty acids:
Unsaturated fatty acids contain one or more double bonds between carbon
atoms.
Example: Oleic acid (C17H33COOH)
If the fatty acid has a single carbon-carbon double bond in the molecule, it
is known as a mono-unsaturated fatty acid. Oleic acid is a mono-
unsaturated fatty acid.
If a fatty acid has two or more carbon-carbon double bonds in the molecule,
it is known as poly-unsaturated fatty acid.
Linoleic acid { CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH } is a poly-
unsaturated fatty acid. It contains two double bonds.
Long chain fatty acids always exist as triglycerides and are found in fats and
oils. Triglycerides are esters of fatty acids and are formed by combining
fatty acids with glycerol.

3. Glycerol has three alcohol functional
groups (-OH group) and fatty acids have
the carboxyl group (-COOH
group). Since glycerol has three –OH
groups, three fatty acids must react with
one glycerol molecule to make three
ester functional groups and form
triesters of glycerol or triglyceride.
During this process three molecules of water are eliminated. The three fatty
acids may or may not be identical.
The long chain fatty acids can be of either plant origin (linseed oil, castor
oil, soya bean, coconut oil) or animal origin (tallow from cattle and sheep).
In general, fats/oils from plant origin are high in unsaturated and low in
saturated fatty acids. Fats/oils from animal source are high in saturated and
low in unsaturated fatty acids.

4. SOAP
Soaps are sodium or potassium salts of long chain fatty acids. When
triglycerides in fat/oil react with aqueous NaOH or KOH, they are converted
into soap and glycerol. This is called alkaline hydrolysis of esters. Since this
reaction leads to the formation of soap, it is called
the Saponification process.
The soap molecule has two parts: a polar group (-COO-Na+)and a non-polar
group (R-hydrocarbon part). The polar group is called the head and the non-
polar group is called the tail. Thus, the soap molecule has a polar head and
a non-polar hydrocarbon tail. The polar head is hydrophilic in nature (water
loving) and the non-polar tail is hydrophobic (water repelling) in nature.

5. The saponification reaction is exothermic in nature, because heat is
liberated during the process. The soap formed remains in suspension form
in the mixture. Soap is precipitated as a solid from the suspension by adding
common salt to the suspension. This process is called Salting out of Soap.
Types of Soap
Depending upon the nature of alkali used in the production of soap, they are
classified into two types.
 Hard soap
The sodium salt of long chain fatty acid is known as hard soap. It is difficult
to dissolve in water. It is used as laundry soap.
 Soft soap
The potassium salt of long chain fatty acid is known as soft soap, as it
produces more lather. It is used as toilet soap and shaving soap.
In aqueous solution, soap ionises to form alkali ions.
Since soaps have free alkali ions, they are alkaline in nature. Hence, the soap
solutions are slippery to the touch.
Preparation Process
There are two process can be done to make soap, cold process and hot
process
Cold process
Even in the cold soapmaking process, some heat is usually required; the
temperature is usually raised to a point sufficient to ensure complete melting

6. of the fat being used. The batch may also be kept warm for some time after
mixing to ensure the alkali (hydroxide) is completely used up. This soap is
safe to use after about 12–48 hours, but is not at its peak quality for use for
several weeks.
Cold-process soapmaking requires exact measurements of lye and fat
amounts and computing their ratio, using saponification charts to ensure the
finished product does not contain any excess hydroxide or too much free
unreacted fat. Saponification charts should also be used in hot processes,
but are not necessary for the “fully boiled hot-process” soaping.
Historically, lye used in the cold process was made from scratch using
rainwater and ashes. Soapmakers deemed the lye solution ready for use
when an egg would float in it. Homemade lye making for this process was
unpredictable and therefore eventually led to the discovery of the sodium
hydroxide by English chemist Sir Humphry Davy in the early 1800s.
A cold-process soapmaker first looks up the saponification value for each
unique fat on an oil specification sheet. Oil specification sheets contain
laboratory test results for each fat, including the precise saponification value
of the fat. The saponification value for a specific fat will vary by season and
by specimen species.[28] This value is used to calculate the exact amount of
potassium hydroxide to react with the fat to form soap. The saponification
value must be converted into an equivalent sodium hydroxide value for use
in cold process soapmaking. Excess unreacted lye in the soap will result in
a very high pH and can burn or irritate skin; not enough lye leaves the soap
greasy. Most soap makers formulate their recipes with a 2–5% deficit of lye,
to account for the unknown deviation of saponification value between their
oil batch and laboratory averages.
The lye is dissolved in water. Then oils are heated, or melted if they are
solid at room temperature. Once the oils are liquefied and the lye is fully
dissolved in water, they are combined. This lye-fat mixture is mixed until
the two phases (oils and water) are fully emulsified. Emulsification is most
easily identified visually when the soap exhibits some level of “trace”,
which is the thickening of the mixture. (Modern-day amateur soapmakers
often use a stick blender to speed this process). There are varying levels of
trace. Depending on how additives will affect trace, they may be added at
light trace, medium trace, or heavy trace. After much stirring, the mixture
turns to the consistency of a thin pudding. “Trace” corresponds roughly to
viscosity. Essential oils and fragrance oils can be added with the initial
soaping oils, but solid additives such as botanicals, herbs, oatmeal, or other

7. additives are most commonly added at light trace, just as the mixture starts
to thicken.
The batch is then poured into moulds, kept warm with towels or blankets,
and left to continue saponification for 12 to 48 hours. (Milk soaps or other
soaps with sugars added are the exception. They typically do not require
insulation, as the presence of sugar increases the speed of the reaction and
thus the production of heat.) During this time, it is normal for the soap to go
through a “gel phase”, wherein the opaque soap will turn somewhat
transparent for several hours, before once again turning opaque.
After the insulation period, the soap is firm enough to be removed from the
mould and cut into bars. At this time, it is safe to use the soap, since
saponification is in essence complete. However, cold-process soaps are
typically cured and hardened on a drying rack for 2–6 weeks before use.
During this cure period, trace amounts of residual lye are consumed by
saponification and excess water evaporates.
During the curing process, some molecules in the outer layer of the solid
soap react with the carbon dioxide of the air and produce a dusty sheet
of sodium carbonate. This reaction is more intense if the mass is exposed to
wind or low temperatures.
Hot processes
Hot-processed soaps are created by encouraging the saponification reaction
by adding heat to speed up the reaction. In contrast with cold-pour soap
which is poured into moulds and for the most part only then saponifies, hot-
process soaping for the most part saponifies the oils completely and only
then is poured into moulds.
In the hot process, the hydroxide and the fat are heated and mixed together
at 80–100 °C, a little below boiling point, until saponification is complete,
which, before modern scientific equipment, the soapmaker determined by
taste (the sharp, distinctive taste of the hydroxide disappears after it is
saponified) or by eye; the experienced eye can tell when gel stage and full
saponification has occurred. Beginners can find this information through
research and classes. Tasting soap for readiness is not recommended, as
sodium and potassium hydroxides, when not saponified, are highly caustic.
An advantage of the fully boiled hot process in soapmaking is the exact
amount of hydroxide required need not be known with great accuracy. They
originated when the purity of the alkali hydroxides were unreliable, as these
processes can use even naturally found alkalis, such as wood ashes and
potash deposits. In the fully boiled process, the mix is actually boiled (100+

8. °C), and, after saponification has occurred, the “neat soap”
is precipitated from the solution by adding common salt, and the excess
liquid is drained off. This excess liquid carries away with it much of the
impurities and color compounds in the fat, to leave a purer, whiter soap, and
with practically all the glycerine removed. The hot, soft soap is then pumped
into a mould. The spent hydroxide solution is processed for recovery of
glycerine.
Molds.
Many commercially available soap molds are made of silicone or various
types of plastic, although many soapmaking hobbyists may use cardboard
boxes lined with a plastic film. Wooden molds lined with silicone sleeves
are also readily available to the general public. Soaps can be made in long
bars that are cut into individual portions, or cast into individual molds.
Purification and finishing
In the fully boiled process on an industrial scale, the soap is further purified
to remove any excess sodium hydroxide, glycerol, and other impurities,
colour compounds, etc. These components are removed by boiling the crude
soap curds in water and then precipitating the soap with salt.
At this stage, the soap still contains too much water, which has to be
removed. This was traditionally done on chill rolls, which produced the soap
flakes commonly used in the 1940s and 1950s. This process was superseded
by spray dryers and then by vacuum dryers.
The dry soap (about 6–12% moisture) is then compacted into small pellets
or noodles. These pellets or noodles are then ready for soap finishing, the
process of converting raw soap pellets into a saleable product, usually bars.
Soap pellets are combined with fragrances and other materials and blended
to homogeneity in an amalgamator (mixer). The mass is then discharged
from the mixer into a refiner, which, by means of an drill, forces the soap
through a fine wire screen. From the refiner, the soap passes over a roller
mill (French milling or hard milling) in a manner similar to calendering
paper or plastic or to making chocolate liquor. The soap is then passed
through one or more additional refiners to further plasticize the soap mass.
Immediately before extrusion, the mass is passed through a vacuum
chamber to remove any trapped air. It is then extruded into a long log or
blank, cut to convenient lengths, passed through a metal detector, and then
stamped into shape in refrigerated tools. The pressed bars are packaged in
many ways.

9. Sand or pumice may be added to produce a scouring soap. The scouring
agents serve to remove dead cells from the skin surface being cleaned. This
process is called exfoliation. Many newer materials that are effective, yet
do not have the sharp edges and poor particle size distribution of pumice,
are used for exfoliating soaps.
Nanoscopic metals are commonly added to certain soaps specifically for
both colouration and antibacterial properties. Titanium dioxide powder is
commonly used in extreme “white” soaps for these
purposes; nickel, aluminium, and silver compounds are less commonly
used. These metals exhibit an oligodynamic effect when in contact with
bacteria, thereby disrupting their functioning and killing them. Since some
of the metal is left behind on the skin and in the pores, the benefit can also
extend beyond the actual time of washing, helping reduce bacterial
contamination and reducing potential odours from bacteria on the skin
surface.
F. Tools and Materials
G. Procedure
Preparation of Soap
1.4 gram NaOH
- Dissolved in 3.3 mL H2O
NaOH solution
10 gram oils; palm, barco, curah
- Each oils undergone same treatment
- Put into beaker glass
- Added 1 gram of stearic acid
- Heated until 70°C, stearic dissolved
- Let it cold until 50°C
- Added NaOH solution, stirred
- Added 12 g alcohol
- Added 4 g glycerin
- Heated, stirred until become clear
- Let it cool, added olive oils, perfume, and
coloring
- Put into cutter
Soap

10. Properties of Soap Emulsion
Number of Acids
H. Result of Experiment
3 ml aquadest + 5 drops oils
- Each oils undergone same treatment
- Put into test tube 1
- Added 2 ml soap solution
- Shaken strongly
- Settling
- Noted time of a layer separation oil and
water
Result
3 ml aquadest + 5 drops oils
- Each oils undergone same treatment
- Put into test tube 2
- Shaken
- Settling
- Noted the time of layer separation
Result
5 gram of each oils
- Each oils undergone same treatment
- Put into erlenmeyer
- Added 25 ml ethanol
- Added 3 drops of PP indicator
- Titrated with 0.1 N KOH
- Repeated 3 times titration
- Calculated the number of acids
Result

11. I. Analysis Data
J. Conclusion
K. References
Board, Niir. 2002. Modern Technology Of Oils, Fats & Its Derivatives.
Delhi: National Institute Of Industrial Re
Fessenden & Fessenden. 1982. Kimia Organik Edisi Ketiga Jilid 1. Jakarta:
Gelora Aksara Pratama.
Hidajati, Nurul dkk. 2014. PenuntunPraktikum KimiaOrganik 2. Surabaya:
UNESAPRESS.
Online Lab. -. Saponification-The process of Making Soap. CDAC
Mumbai & CREATE @ AMRITA. (http://
http://amrita.olabs.co.in/?sub=73&brch=3&sim=119&cnt=1 accessed on
8 November 2014 at 6.21 a.m)
Scharf, Walter and Charles Malerich. -. Preparation of Soap. New York:
Natural Sciences/Chemistry Baruch College
Question
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