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TRANSCRIPT
HISTORY OF SOAP
MANUFACTURING
Soaps have been used for more than 3000 years. In ancient
times, soaps were made from plant ashes (contain potassium
carbonate) and animal fats. Plant ashes were dispersed in water,
and fat was added to the solution.
Ash + Lime boiled Caustic Potash(K2CO3) (CaO) (KOH) Caustic Potash + Animal Fats boiled Soap
Animal fats contain fatty acids which helped to get the process
started. In the end of the Middle Ages, slaked lime used to
causticise the alkali carbonate. Through this process, chemically
neutral fats could be saponified easily.
The introduction of the Leblanc process for the production of
soda ash from brine and by the work of a French chemist, Michel
Chevreul, who showed that the process of saponification is the
chemical process of splitting fat into the alkali salt of fatty acids
(that is, soap) and glycerin help in the manufacturing of soap.
SOAPSoap is the sodium or potassium salts formed when a fatty acid
that contain 12 to 18 carbon atoms per molecule is neutralized
by an alkali.
Fats or vegetable oils + concentrated alkalis soap +glycerol
Soap is cleansing agent made from animal fats or vegetable oils
by saponification.
Saponification is the alkaline hydrolysis of ester using alkali solutions. Some examples of soaps are shown below.
a) Sodium palmitate, C15H31COONab) Sodium oleate, C17H33COONac) Sodium stearate, C17H35COONa
The process through which soap is preparedSoap is prepared by heating fats and oils with an alkali such as sodium hydroxide, NaOH. The oil and fat malecules are hydrolysed to form glycerol and fatty acids. This process is also known as saponification as is the reverse of esterification.
The fatty acids formed react with sodium hydroxide, NaOH a
form a salt and water. This salt is the basic form of soap.
Saponication of oils or fats O ll R’—C—O—CH₂ OH—CH₂ O l ll OH ⁻ OH—CH + R’COOH + R”COOH R”’COOH R”— C—O—CH + 3H₂O l O OH—CH₂ fatty acids ll R”’—C—O—CH₂ glycerol Ester
Neutralization of fatty acids
R’COOH + R”COOH + R”’COOH + 3NaOH R’COONa + R”COONa + R”’COONa + 3H₂O
Salt or fatty acids or soap
The soap produced can be precipitated by adding sodium
chloride, NaCl to the reaction mixture. Sodium chloride, NaCl
reduces the solubility of soap in water. As a result, the
precipitation of soap occurs.
The preparation of sodium palmitate when glyceryl tripalmitates
(ester) is boiled with concentrated sodium hydroxide, NaOH
solution, saponification occurs and a mixture of sodium palmitate
(soap) and glycerol is obtained.
The structure of soap molecule
When soap is dissolved in water, it will dissociate and produce sodium ions and carboxylate ions (RCOO-). For example, sodium stearate dissolves in water to form sodium ions and stearate ions.
C17H35COONa (s) + water C17H35COO- (aq)sodium stearate stearate ions
+ Na + (aq)
The active substance in soap is the carboxylate ion, for example, stearate ion. The stearate ion consist of two parts : the ‘head’ and the ‘tail’. The ‘head’ id negatively charged and the ‘tail’ is a long hydrocarbon chain.
The ‘head’ contains the -C-O- ions which dissolves readily in water (hydrophilic) but does not dissolve in oil. Conversely, the ‘tail’ contains a long hydrocarbon chain which is insoluble in water (hydrophobic) but dissolves readily in oil.
O
Soaps made from palmitic acid are known as sodium palmitate. Figure 5.2 shows the structure of the palmitate ion in soaps. The figure 5.3 9a) shows the molecular model of palmitate ion and Figure 5.3 (b) shows the simple representation of the structure of the palmitate ion.
The molecular model of the palmitate ion.
The diagrammatic representation of the soap ion.
Detergent is the salt formed when an alkyl hydrogen sulphate
is neutralized by an alkali
Detergent is synthetic cleansing agent made from
hydrocarbons obtained from petroleum fractions.
Detergents can be classified into three main types, depending on the charge on the detergent ion.a) Anionic detergents where the head of the detergent
particle contains a negatively charged ion.Example: R – O – SO3
-Na+ (Sodium alkyl sulphate)
b) Cationic detergents where the head of the detergent particle contains a positively charged ion.Example: R – N (CH3)3
+BR-
c) Non ionic detergents
Example: R – O – CH2CH2OH
There are two types of anionic detergents : a) Detergent molecule with a benzene ring such as sodium
alkylbenzene sulphonate.
Where R represents a long hydrocarbon chain.
We can represent the detergent ion, alkylbenzene sulphonate ion, more simply as :
Positively charged ion
Negatively charged ion
b) Detergent molecule without a benzene ring such as sodium alkyl sulphate.We can represent the detergent ion, alkyl sulphate ion as:
R – OSO3-
The process through which detergent is prepared
i. Preparation of of sodium alkyl sulphate
i. Reaction with concentrated sulphuric acid
ii. Neutralisation with sodium hydroxide, NaOH solution
Preparation of sodium lauryl sulphate from the production
of lauryl hydrogen sulphate followed by the neutralization
of lauryl hydrogen sulphate.
An example of a long chain alcohol is didecan – 1 –ol, CH3(CH2)10CH2OH. The detergent prepared from dodecan -1 –ol is called sodium dodecyl sulphate (IUPAC name) or sodium lauryl sulphate (common name). CH3(CH2)10CH2O-SO3
-Na+ .Sodikum alkylbenzene sulphinates, were first used in 1940s. It can be prepared in three steps. The starting materials for making this detergents in a long chain alkene, RCH = CH2 , obtained from the cracking of petroleum.
Preparation of sodium alkylbenze sulphonatea) Alkylation – introduction of the sulphonic acid group
to an organic molecule
b) Sulphonation – introduction of the sulphonic acid
group , -SO3H to an organic molecule to form sulphonic acid
Alkylbenze reacts with sulphuric acid to form alkylbenze sulphonic acid
c) Neutralisation
Alkylbenzene suphonic acid reacts with sodium
hydroxide to form sodium alkylbenze sulphonate
(detergent)
The structure of detergent molecule
Detergents dissolve in water to form sodium ions, Na+ and
detergent ions.
The detergent ions consists of two parts; the head and the
tail.
The head is the sulphate group, -OSO3- or the sulphonate
group, -OSO3- , which is negatively charged and hydrophilic
(dissolves in water).
The tail is the long hydrocarbon chain, which is neutral and
insoluble in water (hydrophobic) but dissolves readily in oil or
grease.
The structure of alkyl sulphate ion in detergent
alkyl sulphate ion
Alkylbenzene sulphonate ion
The cleansing action of soap and detergent
a) When soap or detergent is added to the dirty surface
of a piece of cloth, the hydrophohic part of the soap
or detergent ions dissolves in grease. The hydrophilic
part of the soap or detergent ions dissolves in water.
b) If the water is agitated and lifted off the surface.
c) The grease is lifted off the surface and suspended in
water. The hydrophilic part of the soap or detergent
ions surround the grease.
d) The grease is dispersed into smaller drops that float
in water. Heating, rubbing, and scrubbing can help
this process.
e) When the cloth is rinsed with water, the grease
droplets will be removed.
The effectiveness of the cleansing action of soap and detergent
Additives in detergents
Property Soap Detergent
Cleaning power Less powerfull More powerfull
Ease of rinsing It is difficult to wash away all soap on clothes. The soap that remains leave and odour and spoils the fabric
Rinse out well from clothes
pH Slightly alkaline Can be controlled to suit the cleaning task
Molecular structure
Determined by the fatty acids found in the oil or fat used to produce soap
Can be modified to suit the cleaning task. For example, a detergent can be made specially for cleaning toilet bowls.
Formation of scum
Forms scum with hard water
Does not form scum with hard water
1. Modern detergents used for washing clothes usually contains a
few types of additives to :
a) Increase their cleaning power.
b) Make them attractive and saleable.
2. Only about 20% of the substances in a detergent are cle4ansing
agents (sodium alkyl sulphate or sodium alkylbenzene
sulphonate). The other substances are additives. The examples
of addictives and their functions are described as follows :
3. Builders : Sodium tripolyphosphate (Na 5P3O10)
a) Sodium tripolyphospathe is usd to soften hard water. In the
presence of sodium tripolyphosphate, Ca2+ ions and Mg2+
ions are removed.
b) Sodium tripolyphosphate increases the pH value of water.
In this way, muddy dirt can be removed.
4. Whitening / bleaching agents : sodium perborate
a) Bleaches (bleaching agents) remove coloured stains by
oxidation process. When coloured stanis are oxidized, the
colour will disappear.
b) The whitening (bleaching) agents commonly used in
detergent are sodium perborate (NaH2BO43H2O). Sodium
perborate decomposes in hot water to release oxygen (an
oxidising agent) which is responsible for the whitening
(bleaching) action.
c) Unlike chlorine, oxygen does not bleach the colour of dyes
are not damaging to fabrics. When properly used, the
perborate bleaches make fabrics whiter than chlorine
bleaches and the colourful dyes of the fabrics do not fade
when dirty stains are removed.
d) Besides sodium perborate, sodium hypochlorite, (NaCIO)
can also be used as bleaches in detergents. The IUPAC
name of sodium hypochlorite is sodium chlorate (I).
e) Sodium hypochlorite releases chlorine that bleaches with
dirty stains. However, high concentrations of chlorine can
be quite damaging to fabrics. These bleaches do not work
well on synthetic fabrics (polyster fabrics), often causing a
yellowing rather than the desire whitening. Also chlorine
causes the dyes on fabrics to fade.
5. Biological enzymes : Amylase, lipase, and protease
a) Protein stains such blood, milk, and tomato sauce cannot
be removed by the ordinary detergents because these
types of stains are insoluble in water.
b) Biological enzymes in detergents can break down fat and
protein molecules in food stains. The fatty acids, glycerol
and amino acids produced are soluble in water and are
removed during washing.
6. Brighteners
a) Figure below shows the action of brighteners. The
brighteners absorb the invisible ultra-violet and re-radiate
it as blue light.
Brightener
Cloth
b) Brighteners make fabrics appear whiter and brighter
because the blue light can hide any yellowing on the
fabrics. Blue light added to the yellow light reflected on old
fabrics make them look white.
7. Drying agents ; Sodium sulphate and sodium silicate
Anhydrous sodium sulphate and sodium silicate (Na2S2O3) are
used as drying agents to ensure that the detergent in powdered
firm is always in a dry condition.
8. Stabilisers
a) The functions of stabilizers is to prevents the formation of
foam.
b) In an automatic washing machine, excessive foam can
stop the pump working. So, washing powders for
automatic washing machine are made using detergents
that are good at removing and emulsifying grease, but do
not produced foam.
9. Perfumes
Perfumes are added to make clothes smell fresh and clean.
FOOD ADDITIVES
Food additive Food additive is any substance that is added to food in small
quantities to preserve or improve its flavour and appearance.
Uses of food additivesTo make food last longer (to extend the shelf life)To make foods taste better and look better
The rationale for the use of food additives.
To make sure that certain food remains edible throughout the
year.
Types of food additives
Preservatives: sodium nitrite, sodium benzoateAntioxidant: ascorbic acidFlavouring: Monosodium glutamate(MSG), aspartameStabiliser and thickener: gelatin and acacia gumDye: azo compounds, triphenyl compounds
Effects on health
Allergy: MSGCarcinogenic: NaNO₂Brain damageHyperactivity
Functions of food additives
Preservatives: to inhibit or prevent the growth of moulds, yeast and bacteria that spoil foodsAntioxidants: to prevent spoilage of food due to oxidation by oxygenFlavouring agents: to enhance the taste of foodStabilisers and thickeners: to improve the texture of foodsColouring agents: to restore the colour or to enhance the natural colour
A considerable number of food is harvested seasonally. In
such cases preservatives are added to make sure that they do
not get spoilt, and remains edible after along time.
Additives such as vitamins B, C, and D, and minerals such as
iron is added to improve the nutritional value of foods which
may be destroyed during food processing.
Food additives are used as an artificial sweeteners for diabetic
patients.
Food additives such as potassium iodide in table salt is used
to reduce the incidence of goiter.
The use of food additives such as vitamin C in fruit juices
prevents scurvy, vitamin D in milk and vitamin A in margarine
prevent rickets.
The effects of food additives on health and the environment.
Additives in food should be limited. This is because all the
additives used are chemicals, and over a long period of time
they may have adverse effects in our body. Moreover, no
additive has been proven to be 100% safe. Scientific
knowledge should be applied in the management of food
additives.
Example:
o The excessive use of the flavouring agent monosodium
glutamate (MSG) is harmful, because it causes headaches,
poor vision and dries up the throat, giving rise to unnatural
thirst.
o Food additives such as sodium sulphite, MSG and some
food colours can cause allergic reactions in some people.
o Food additives such as sodium nitrate is carcinogen.
o The excessive intake of nitrites over a long period can
cause brain damage.
o Food additives such as tartrazine can cause hyperactivity.
The functions of food label.
To let the consumers know about the nutrient content, food
additives used, expiry date, halal or non-halal, whether
containing any permitted or prohibited chemicals or whether
the food is good or bad for health.
Life without food additives.
Food spoilage occurs. Food supplies will be reduced and there
will be food shortage around the world.
Deficiency of vitamins and minerals in foods because the
nutritional value of foods may be destroyed during food
processing.
Malnutrition happens especially among the younger
generation due to the loss of appetite because foods do not
look attractive, do not taste delicious or smell good.
Medicine
Drugs
Chemical compounds that are used as medicine to heal any sort
of ailment is known as drugs
Traditional medicines
Traditional medicines are derived from mostly different types of
plant parts or animal parts. They are generally less harmful over
a long period of time when compared to drugs.
Examples of traditional medicine and their uses.
The types of modern medicine, their examples and functions.
PlantLocal nameUsesAloe veraLidah buayaSap used to relieved pain from burnsBetelSirehLeaves relieved sore
eyesBitter gourdPeriaFruit used to cure diabetesCoconutKelapaYoung coconut water reduces
feverGarlicBawang putihReduces infection and hypertensionGingerHaliaReduces inflammation and
improves blood circulation and digestionGinsengGinsengRoots maintain good
healthHibiscusBunga RayaLeaves relieves headache and hair lossTurmericKunyitCures pimples
Type of modern medicineFunctionExamplesAnalgesicsRelieve painAspirin, paracetamolAntibioticsKill or inhibit
growth of infectious bacteriaPenicillin, streptomycinPsychotherapeutic medicinesControl
symptoms of mental illnessStimulants, antidepressants
Side effects of medicines
Both traditional and modern medicines have side effects
Some traditional medicines help people lose their weight by
speeding up their metabolism. The side effects are an increase in
blood pressure and heart rate
Birth control pills are an example of modern medicine. Women
who use them experience side effects such as hypertension,
acne, and abnormal bleeding.
Correct ways of using medicines
Use the correct amount or dosage and using it for the correct
purpose
For example, using antibiotics to treat infections caused by
viruses is drug misuse. This is because antibiotics have no effect
on viruses.
Drug abuse is using drug for its intoxicating effect. For example,
the use of Morphine, Viagra and ecstasy pills.
The significance of chemicals in the world today and its side effects.
Chemical have become an integral part of today’s lifestyle.
Each and every toiletry, cosmetic, or food that we use or
consume is some way or the other related to chemicals. From
the moment we get up from bed, the toothpaste we use to
brush our teeth, the soap, the shampoo and detergent that
we use and the breakfast cereal that we eat have some form
of chemical or other.
However, chemicals are not 100% organic friendly. For this
reason, before eating preserved food we should think whether
we can possibly replace it with some other organic food, or
while using cosmetics or toiletries, we should choose the ones
that have reduced chemicals.
A life without chemicals is impossible. Hence, it is up to us to
use them wisely and sparingly.