It is about of finding the free alkalinity in the given soap sample. As to enhance the quality of soap in marketing, it become necessary to check the free quantity of free alkalinity in soap as it is sever for skin.

1. Experiment Number 02:
Determination of free alkalinity in soap sample
Outlines
I. Introduction about soap
II. Saponification
III. Fatty acids
IV. Distinction b/w fats and oils
V. Occurrence
VI. Cleaning action of soap
VII. Free alkalinity in soap
VIII. Effect of free alkalinity in soap
IX. Normality
X. Equivalent weight of solute
XI. Objective of experiment
XII. Apparatus
XIII. procedure
XIV. Observation and calculation
XV. Conclusion
i.Introduction about soap
Soap:
Soap is a sodium salt of fatty acids and sodium hydroxide.These fatty acids contain long carbon
chains, exists in the form of oils and fats. Soap is used for many purposes like washing, as a catalyst and
surfactants.
ii.Saponification:
A chemical reaction which is occurred b/w acid and base to form a soap
salt is called saponification reaction. This is also known as neutralization reaction b/w oils and NaOH.

2. The value of saponification is judged by the amount of base required to saponify a fat sample.
iii.Fatty Acids:
Fatty acids are straight chain monocarboxylic acids, and the most common range in size
frome 10-20 carbon atoms and most often have an even no of carbon atoms including the carboylic group
carbon. The carbon-carbon bonds in saturated fatty acids are all single bonds, while unsaturated fatty
acids have one or more carbon-carbon double bonds in their chains. One example of saturated fatty acid is
palmitic acid.
The bond b/w the fatty acid and the glycerol backbone is referred to as an ester linkage.
iv.Distinction b/wfats and oils:
The distiction b/w fats and oils is primarily
based upon the difference in melting points. Fats are composed of solid triesters of glycerol, while oils are
composed of liquid triesters of glycerol at room temperature. However, this distiction is not well founded
as the melting point depends on
climate and weather. The same glyceride may be solid at a hill station and liquid in planes.
The melting point of a fat or oil depends on its structure. If all the fatty acids forming a triglyceride
saturated, their carbon-carbon can align themselves in a regular pattern. Such molecules can pack well in
a crystal, and thus form solids at room temperature. On the other hand; if some of the ester chains are
formed by unsaturated acids, there are kinks in their carbon-chains at the double bonds that have cis
configuration. Thus in general, oils contain glycerides in which unsaturated acids preponderate. On the
other hand, in solid fats saturated acids preponderate.
v.Occurrence:
Fats or oils occur widely spread both in plants and animals.
i. In plants
Plants store large quantities of fats in their seeds, roots, and fruits, cotton seeds,
castor beans, olives have a high fat contents.
ii . In Animals
In animals, the fat deposits are to be found mostly under the skin and around the intestines
and kidneys.
vi.Cleaning action of soap:

3. Skin is covered with a thin layer of natural oil or
grease which cathes dirt. The soap molecules have a long chain nonpolar hydrocarbon tail that is oil
soluble and a negative head COO^- which is water soluble. As soap water is poured over the skin , the
hydrocarbon tails of the soap molecules peg into it, while the negative head is held in water. The grease
layer is then dislodged from skin by rubbing or from garment by tumbling and stirring. Each grease
globule thus separated is pinoushioned by hydrocarbon tails with negative heads outsides in water. The
negative globules keeps apart by mutual repulsions, and are said to have been emulsified.
vii.Free Alkalinity in soap:
As above it is discussed that soap salt is formed by the
saponification reaction b/w acids and base NaOH. Sometime proportion of acids or base cannot be
remained same. So one of them remained in excess amount and the other reactant acts as a limiting
reactant. So the reactant which is present in excess amount goes to the product as an unreacted amount
which remained after finishing as a limiting reactant.
In some soap products, NaOH Present as an unreacted reagent due to unequal ratio of acid and
base.
viii.Effect of free alkalinity in soap:
Free alkalinity in soap is present in the form of Na2O and NaOH.
➢ These bases have bitter taste and soapy feel.
➢ These free bases cause irritation on human body.
➢ These free bases cause to decrease the marketing of the soap.
Refrence; Applied chemistry by B.S Bhal
ix.Normality:
The normality of a solution is the gram equivalent weight of a solute per litter
of solution.
It is indicated by the symbol of N. For example, the concentration of HCl solution expressed
sometimes as 0.1N
Normality = equivalent weight of solute
1 litter of solution
X.Equivalent weight of solute:
Eq.wt. Acid= molecular weight of solute

4. Basicity of a solute
Eq.wt. Base = Molecular weight of solute
Acidity of solute
Equivalent Weight
Normality of concentrated solutions:
Example;

5. Normality of H2SO4 =?
If sulfuric acid by weight= 60gram
Volume of solution= 800ml
Solution
Equivalent weight =98/2= 49
N= (60gram)(1000) =1.53N
(49)(800ml)
Normality and molarity relation
They are related by the equation of
N=M×n
Where
N= normality
M= molarity
n= acidity or basicity
For monovalent compounds
n=1; Normality and molarity is same.

6. Example:
If normality of AlCl3 solution is 0.6N.then molarity=?
Solution:
refrence; Chemical principle engineering book 6th edition
xi.ExperimentObjective:
To find out the amount of free alkali in given sample soap.
xii.Apparatus:
o Conical flask
A type of flask, generally round-bottomed, usually suspended and
heated from below. Its shape makes it easy to swirl and mix liquids inside of it.

7. o Stirrer
used to dissolve the solids in the liquid quickly .
o Burrete
An extremely accurate device with a stopcock at the bottom used to measure
volumes of reagents
o Beaker
A flat-bottomed, cylindrical piece of glassware used for mixing and heating
compounds
o Funnel

8. Used together with filter paper to filter precipitates out of solutions.
o Filter paper
used to separate the residues from the solution.
refrence
(https://www.dummies.com/education/science/chemistry/ap-chemistry-an-overview-of-common-lab-equipment/)
xiii.Procedure:
▪ Take 5g of soap sample in a beaker.
▪ Mixed this soap sample with 95ml of spirit and make a solution.
▪ Solution is continuously stirrer.
▪ Filter the solution using filter paper.
▪ Separate the filtrates (filter particles) in a conical flask and added 2-3 drops of
phenolphthalein indicator.
▪ Note the color of the solution (Pink).
▪ Titrate this solution with 0.1N solution of HCl until its color get disappear.
▪ The volume of HCl used is measure, it is the end point.

9. xiv.Observations & Calculations:
Observations:
Mass of soap=5g
Alcohol added=95ml
Ca=Normality of HCl=0.1N
Volume of filtrate used for titration=Vb=95ml
Volume of acid used=Va=10.2ml
Indicator→Phenolphthalein
Initial Color= Pink
Final Color= Colorless
Calculations:
Na2O→ Free Alkali
Na2O+2HCl→2NaCl+H2O
nb=1 na=2
We have
na/nb= (Ca×Va) /(Cb×Vb)
Cb= nb(Ca ×Va) /na×Vb
Cb= 0.1N×10.2ml×1
2×95ml
Cb=0.00536N-------------------- (1)
To convert it into grams
Na2O (Di-Basic)= 62/2=31
So (1) becomes
Cb=0.00536×(31/1000cmᶾ)
Cb= 0.1661/1000cmᶾ
1000ml of sample has alkalinity= 0.1661g
95ml of sample has alkalinity= (95×0.1661g)/1000
= 0.01578g
Percentage(%)=Alkalinity in soap × 100
Sample of soap

10. =0.01578 ×100
5
Percentage(%) = 0.315%
xv.Conclusion:
After calculation we obseved that in soap free alkali is
present which will effect on human body and cuase to decrease the marketing of soap.