Soap is the sodium or potassium salt of a longchain fatty acid.
Sodium
Stearate
Because “like dissolves like” the nonpolar end of
the soap molecule can dissolve the greasy dirt,
and the polar or ionic end of the molecule is
attracted to water molecules.
An emulsifying agent is a substance
used to disperse one liquid in the
form of finely suspended particles or
droplets in another liquid. This is
what soap is…
Sketch courtesy of:
http://www.chromatography.amershambiosciences.com/
When we treat fats or oils with strong bases
such as lye (NaOH) or potash (KOH) they
undergo hydrolysis and form glycerol and soap.
Because soaps are salts of strong bases and weak
acids, they should be weakly basic. However,
sometimes soap can be basic enough to cause skin
damage so an alkalinity test must be performed on
our soap after we make it today.
Soap becomes ineffective in hard water. Hard
water contains large amounts of Ca2+ and Mg2+
salts. Because of this, synthetic detergents
have become common alternatives for soap.
In acidic solution, soap is converted to free
fatty acid and therefore loses its cleansing
action.

Use vegetable oil to make soap.

Use alcohol as a solvent and NaOH to hydrolyze
the fatty acid into our soap compound.

Filter our soap.
Test the properties of soap…



Emulsifying properties: we will mix oil and water
and see how the addition of our soap effects the
mixture’s ability to form an emulsion.
Hard water reactions: we will test our soap with
minerals associated with hard water to
demonstrate their effects on our soap.
Alkalinity - we will test the basicity of our soap.
Alcohol is flammable! Do not allow near an
open flame or heat source.
Do not take your soap home for personal
use!!


Inhalation: irritant, coughing, shortness of breath, drowsiness, loss
of appetite, aspiration pneumonia, chemical pneumonitis,
pulmonary edema, coma
Ingestion: irritation of the mucous membranes, mouth, throat and
digestive tract, gastrointestinal upset, vomiting, abdominal pain,
vomiting, diarrhea, central nervous system depression,
hypocalcemia, lack of reflexis, headache, gastritis, intoxication,
blindness, low blood pressure, tachycardia, skin discoloration,
rigidity, convulsion, dehydration, organ congestion, perforation,
shock, coma, death

Skin contact: irritant, burns, cracking, flaking, defatting of skin,
absorption through the skin, dermatitis, ulcers, rash, cyanosis

Eye contact: mechanical abrasion of the eyes, tearing, burns, pain,
blurred vision, conjunctivitis, corneal damage

Tumorigen, mutagen, teratogen and reproductive effector