Soap Making and Uses of Sodium Hydroxide
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S
o
a
p
•
Describe how soap is made from fatty acids and
alkalis
•
Describe the uses of organic acids in soaps and
detergents
•
Describe the uses of sodium hydroxide to
illustrate its economic importance in producing
soaps
1
SOAP
2
The
raw materials
needed
to make soap are
fats or
oils
and an
alkali
such as
sodium hydroxide.
Soap is one of the
earliest
detergents
. It is known to
have been used for 3000
years.
WATER - LIMITATIONS
3
T
he
fat
would have
come from an
animal
, e.g. sheep,
and the alkali
made from the
chemicals present
in the ashes of a
fire.
1 can of lye (sodium hydroxide),
12 ounces
3 pounds of lard
Water
4
WATER - LIMITATIONS
Fats and oils are examples of
esters
(a family of
organic compounds). They are formed from the
reaction between
organic acids
and
alcohols
.
5
SOAP
e.g. Stearic acid is a saturated fat that's mainly in
animal products.
C
18
H
36
O
2
glycerol
C
3
H
3
(OH)
3
Stearic acid
+
Glyceryl sterate + water
6
SOAP
When glyceryl stearate is boiled with alkali the following
reaction occurs:
sodium + glyceryl
sodium
+ glycerol
hydroxide tristearate
stearate
(ALKALI) (ESTER) (SOAP)
When the sodium stearate is first added to water it
dissolves and the stearate ion is released:
7
SOAP
As with any detergent, the hydrocarbon tail is…
HYDROPHOBIC (water hating / grease loving)
the ionic head is…
HYDROPHILIC (water loving / grease hating)
8
Oven cleaners
contain
strong alkalis
that react with
the fats to form a soap. This
can then be removed easily
with a wet cloth.
The inside of an oven
becomes coated with
fats
from the cooking of food,
especially
meat
.
OVEN CLEANERS
9
SOAPS
Soaps themselves are often slightly alkaline.
pH balanced soaps are also available –
soaps that have a pH similar to that of
our skin - about 5.5. These are referred
to as pH balanced soaps.
The surface of our skin is covered in oils
and these can react with the alkaline soap
to form more soap and thus removes the
oils and makes our skin feel ‘dry’..
The more expensive soaps contain ‘moisturisers’ that
restore the skin to its normal state.
Soap, an ancient detergent made from fatty acids and alkalis like sodium hydroxide, has been utilized for over 3000 years. Fats and oils are essential raw materials for soap production, and organic acids play a role in creating esters. Sodium hydroxide, a key component in soap making, showcases its economic importance. It is used in forming soap and detergents, illustrating the hydrophobic and hydrophilic properties crucial for cleaning. In household applications, strong alkalis react with fats in oven cleaners to form soap for easy removal of grease.
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Presentation Transcript
Soap Soap Describe how soap is made from fatty acids and alkalis Describe the uses of organic acids in soaps and detergents Describe the uses of sodium hydroxide to illustrate its economic importance in producing soaps 1
SOAP Soap is one of the earliest detergents. It is known to have been used for 3000 years. The raw materials needed to make soap are fats or oils and an alkali such as sodium hydroxide. 2
WATER - LIMITATIONS The fat would have come from an animal, e.g. sheep, and the alkali made from the chemicals present in the ashes of a fire. http://bp1.blogger.com/_eOBTgTn007E/SCjxQeFmNoI/AAAAAAAAAso/5YcA4epTQz4/s400/lardDSC_2040.jpg 1 can of lye (sodium hydroxide), 12 ounces 3 pounds of lard Water 3
WATER - LIMITATIONS Fats and oils are examples of esters (a family of organic compounds). They are formed from the reaction between organic acids and alcohols. Organic acids contain the carboxyl group, COOH, and a long hydrocarbon chain: 4
SOAP e.g. Stearic acid is a saturated fat that's mainly in animal products. + http://upload.wikimedia.org/wikipedia/commons/thumb/3/38/Octadecanoic_acid_%28stearic%29.png/375px-Octadecanoic_acid_%28stearic%29.png File:Glycerol-3D-balls.png C18H36O2 Stearic acid C3H3(OH)3 glycerol Glyceryl sterate + water 5
SOAP When glyceryl stearate is boiled with alkali the following reaction occurs: sodium + glyceryl sodium + glycerol hydroxide tristearate stearate (ALKALI) (ESTER) (SOAP) When the sodium stearate is first added to water it dissolves and the stearate ion is released: 6
SOAP As with any detergent, the hydrocarbon tail is HYDROPHOBIC (water hating / grease loving) the ionic head is HYDROPHILIC (water loving / grease hating) 7
OVEN CLEANERS The inside of an oven becomes coated with fats from the cooking of food, especially meat. Oven cleaners contain strong alkalis that react with the fats to form a soap. This can then be removed easily with a wet cloth. 8
SOAPS http://www.realitytvmagazine.com/blog/images/2008/10/hand_washing.jpg Soaps themselves are often slightly alkaline. The surface of our skin is covered in oils and these can react with the alkaline soap to form more soap and thus removes the oils and makes our skin feel dry .. The more expensive soaps contain moisturisers that restore the skin to its normal state. pH balanced soaps are also available soaps that have a pH similar to that of our skin - about 5.5. These are referred to as pH balanced soaps. 9
