Chapter 5 Chemicals For
Consumers
5.1 Soap And Detergent
Soap And Detergent
Chapter 5 Chemicals For Consumers
Soap
Soap is the sodium or potassium salt of an organic acid (fatty acid).
Ordinary soap is usually sodium stearate (C17H35COONa) or sodium
palmitate (C15H31COONa) salt.
It is formed when stearic acid or palmitic acid is neutralised by sodium
hydroxide, NaOH
The reaction is represented by the chemical equation below:
C17H35COOH + NaOH → C17H35COONa + H2O
Stearic acid
sodium stearate (soap)
C15H31COOH + NaOH → C15H31COONa + H2O
palmitic acid
sodium palmitate (soap)
Preparation of Soap
Soap is prepared by heating vegetable oil with caustic alkali.
Vegetable oil is a natural ester and can be hydrolysed by sodium hydroxide into soap.
The oil and fat molecules are ‘broken up’ or hydrolyzed to form soap and glycerol
The process is the reverse of esterification. It is called saponification.
A mixture of vegetable oil and concentrated sodium hydroxide, NaOH is heated.
Soap And Detergent
Chapter 5 Chemicals For Consumers
Saponification of oils or fats
Process involved:
1. Hydrolysis of oil or fats
2. Neutralisation of fatty
acids
General equation:
Then, a concentrated sodium chloride solution is added to precipitate out the soap.
Sodium chloride decreases// lowers the solubility of the soap.
The soap is purified before perfumes and colouring are added.
Soap And Detergent
Chapter 5 Chemicals For Consumers
Saponification of oils or fats
Activity: To prepare soap using the saponification process
Apparatus:
50 cm3 measuring cylinder, 250 cm3 beakers, spatula,
glass rod, filter funnel, wire gauze, tripod stand,
wash bottle, test tube, Bunsen burner.
Materials:
Palm oil, 5 mol dm-3 sodium hydroxide,NaOH
solution, solid sodium chloride, NaCl, filter papers,
distilled water.
Procedure:
1.10cm3 of palm oil is poured into a beaker.
2.50cm3 of concentrated sodium hydroxide solution is added to the palm oil.
3.The mixture is heated until it boils.
4.The mixture is stirred with a glass rod.
Properties of soap:
5.The mixture is allowed to boil for 10 minutes.
1. Feel slipery
6.The beaker is removed from the heat. 50cm3 of distilled water and
2. Forms lather when it
three spatulas of sodium chloride are added to the mixture.
is shaken with water
7.The mixture is boiled for another 5 minutes.
8.The mixture is allowed to cool.
9.The soap is filtered out. The soap is washed with a little distilled water.
10.The soap is pressed between a few pieces of filter paper to dry it.
11.The soap is felt with fingers. A small amount of the soap is placed in a test tube.
Water is added into the test tube. The mixture is then shaken.
12.The observations are recorded.
Soap And Detergent
Chapter 5 Chemicals For Consumers
Detergent preparation - sodium alkyl sulphate
Step 1 : Sulphonating of alkyl alcohol
Alkyl sulphonic acid
Step 2 : Neutralisation
The alkyl sulphonic acid is neutralized by using sodium hydroxide.
Sodium alkyl sulphate (Detergent)
Soap And Detergent
Chapter 5 Chemicals For Consumers
Detergent preparation - sodium alkyl benzene sulphonic
Step 1 : Alkylation
Step 2 : Sulphonation
Step 3 : Neutralisation
Sodium alkyl benzene sulphonate
Soap And Detergent
Chapter 5 Chemicals For Consumers
Additives are added into detergent to make it more effective
Additive
Example
Function
Biological enzyme Amylases, proteases,
celluloses and lipases
To remove protein stains such as
blood.
Whitening agent
Sodium perborate
To convert stains into colourless
substances
Optical whitener
Fluorescent dyes
To add brightness and whiteness to
white fabrics.
Builder
Sodium tripolyphosphate
To enhance the cleaning efficiency
of detergent by softening the water
Suspension agent carboxymethylcellulose
To prevent the dirt particles removed
from redepositing onto cleaned
fabrics.
Filler
Sodium sulphate, sodium
silicate
To add to the bulk of the detergent
and enable it to be poured easily.
Foam control
agent
Silicones
To control foaming in detergent.
Fragrance
-
To add fragrance to both the
detergent and fabrics.
Chapter 5 Chemicals For Consumers
Soap And Detergent
Cleansing action of soap and detergent
Hydrophobic section
(non polar end)
Hydrophilic section
(polar end)
The soap and detergent molecule consists of two sections.
Non polar section
Polar section
Is called hydrophobic
Is called hydrophilic
Has no charge
Has negative charge
Soluble in greasy surfaces
Soluble in water
Soap and detergent consist of
hydrocarbon chain
Soap: hydrophilic group consists
of the carboxylate (-COO-)
group
Detergent: consists of the
sulphonate (-SO3) or
sulphate -OSO3) group.
Soap And Detergent
Chapter 5 Chemicals For Consumers
Cleansing action of soap and detergent - Continued
Soap or detergent dissolves in water and reduce the surface tension of
water.
Surface tension is the attractive force between water molecules. This
force prevent water from wetting a surface.
The hydrophobic section of the soap dissolves in grease whereas the
hydrophilic section dissolves in water.
This lowers the surface tension of the water and increases the wetting
power of the water.
The grease can be separated from the fabric. Soap acts as a wetting
agent.
Any brushing or agitation of the water will help to lift the grease from the
surface of the fabric and also causes it to break into tiny grease droplets.
These oil droplets are suspended in the solution.
Suspension of oil in water is called an emulsion
Thus soap and detergent acts as emulsifying agents.
Rinsing away the dirty water removes the grease droplets
Soap And Detergent
Chapter 5 Chemicals For Consumers
Comparing the effectiveness of cleansing action of soap and detergent in hard water
Cleansing action of soap in hard water
is ineffective because the soap particles
react with the calcium and magnesium
ions in the hard water to form insoluble
salts called scum.
Cleansing action of detergent in hard
water is still effective because the
calcium and magnesium sulphate or
sulphonate salts are soluble in water.
2RCOO-(aq) + Ca2+(aq)  (RCOO)2Ca(s)
2RCOO-(aq) + Mg2+(aq)  (RCOO)2Mg(s)
This means that the detergent particles
are not precipitated out and are available
to remove the grease spot.
The amount of soap particles that remain
for cleansing the grease is reduced.
Chapter 5 Chemicals For Consumers
Soap And Detergent
Effect of soap and detergent on environment
Detergent
Soap
• All soaps are biodegradable.
• Not all detergents are biodegradable.
• They are made from vegetable oil • Those detergents with branched
like palm oil.
chains are non-biodegradable.
• It can thus be broken down by
•These detergents pollute our water.
microorganisms.
Examples of non-biodegradable
detergent
Example
detergent
of
biodegradable
Chapter 5 Chemicals For
Consumers
5.2 Food Additives
Chapter 5 Chemicals For Consumers
Food Additives
Food is an organic substance and will rot if left for some time.
Thus raw foodstuff have to be processed so that its storage time
is lengthened. The table below shows the various additives which
are added to processed food.
Food
additives
Preservatives
Antioxidants
Function



Prevents or
slows down
the growth of
bacteria or
fungi, so that
food can be
kept longer.
Examples of
chemicals





Slows down

the oxidation
of fat in food.
Prevents oily

or fatty food
from becoming
rancid.
Examples of
food
Benzoic acid 
Sodium

benzoate
Tartrazine
Sulphur
dioxide
Sodium
nitrite
Ascorbic
acid
(vitamin C)
Citric acid


Side effects on health
due to excessive use
of food additives
Sausage
Can cause
Canned food Tiredness
Itchy skin
Disturbance in the
digestive system
Diarrhea
Destruction of certain
vitamins
Food poisoning
cancer
Margarine
Cooking oil


Damage to the
liver, brain and
kidneys
Hair loss
Chapter 5 Chemicals For Consumers
Food Additives
Food
additives
Flavouring
agents
Function

Examples of
chemicals
Adds taste or

fragrant smells
to make food
more edible.

Examples of
food
Monosodium 
glutamate

(MSG)
Aspartame
(sweetener)
Ice cream
Soft drinks
Side effects on health
due to excessive use
of food additives








Stabilisers



Mixes two
liquids that
usually do not
mix together.
Prevents the
sedimentation
process of
liquids.
Provides a
smooth and
uniform texture.



Lecithin
Gelatin
Acacia gum
(agar)


Chilli sauce
Ice cream
Chest pains
Weakness in the
body
Nausea
Dizziness
Shortness of
breath
Headaches
Brain damage in
babies and
children
Increase in
heartbeat rate
Chapter 5 Chemicals For Consumers
Food Additives
Food
additives
Thickening
agents
Function

Examples of
chemicals
Thickens liquid 
such as soup
and sauce.

Gelatin
(agar)
Starch
Examples of
food


Colouring
agents / Dyes

Colours food
to make it
looks more
attractive




Metanil
yellow
Caramel
Azo
compounds
Triphenyl
compounds


Side effects on health
due to excessive use
of food additives
Thick
ketchup
sauce
Oyster
sauce
Ice cream
Soft drinks







Cancer
Asthma
Food poisoning
Infertility
Stunted
development of a
child’s mind
Hyperactive
children
Skin diseases
Chapter 5 Chemicals For
Consumers
5.3 Medicine
Chapter 5 Chemicals For Consumers
Medicine
• Medicine are chemicals
• Medicine could be natural or synthetic
• Chemicals that are used as medicines are called modern medicines.
Traditional medicines
1. Medicines that are obtained from plants or animals are called traditional
medicines
2. Traditional medicines are: used to cure diseases
3. Medicines or ingredients for medicines are taken from part of plants such
as roots, leaf, stems, seed, fruits, thorns and sap
4. Most traditional medicines are prepared by boiling
5. Example: ginger is boiled as liquid to drink
6. Ginger part can also be crushed or mashed to make paste
7. The paste is then to rub or massage the affected part of body
Chapter 5 Chemicals For Consumers
Medicine
Traditional medicines
Common name
Local name
Uses
Aloe vera
Lidah buaya


Betel
Bitter gourd
Clove
Coconut
Garlic
Ginger
Sireh
Peria
Bunga cengkih
Kelapa
Bawang putih
Halia




Ginseng
Hibiscus
Papaya
Ginseng
Bunga raya
Betik




Tamarind
Turmeric
Sea cucumber
Asam Jawa
Kunyit
Gamat







sap used to relieve pain from burns
for treating itchy skin
Leaves relieve sore eyes
Fruit used to cure diabetes
Relieves toothaches
Young coconut water reduces fever
Reduces infection and hypertension
For treating stomach pain due to wind in the stomach
For supplying heat energy to keep the body warm
For preventing flu attack
Roots maintain good health
Leaves relieve headaches and hair loss
Seeds to to deworm children
Sap used to relieved skin rashes
Juice of fruit reduces coughing
Cures pimples
To treat Japanese encephalitis and hole in heart.
Chapter 5 Chemicals For Consumers
Medicine
Modern medicines
Category
Antibiotics
Analgesics
Psychotherapeutic
medicine
Hormones
and
Steroids
Function
Examples
Kills or prevents the Penicillin
growth
of
disease Streptomycin
causing microorganisms. Tetracycline
Paracetamol
Remove pain and fever
Aspirin
from body
Codeine
To treat patients
mental problems.
with
To
treat
hormone
imbalances due to injury
or
disease
to
the
endocrine glands.
Stimulants – Increase brain activity.
Antidepressants – Reduce
depression in patients.
Antipsychotic- Treat schizophrenic
patient
Insulin
Tyroxine
Progesterone
Testerone
Medicine
Chapter 5 Chemicals For Consumers
Side effects of analgesics
Aspirin
•
•
•
•
Aspirin contains the acidic group -COOH.
Gastric patients must not take this medicine.
Small children should also avoid this medicine as their
intestinal walls are thin and the acid can cause intestinal
bleeding.
We can substitute aspirin with paracetamol.
Paracetamol
Causes blood disorders, skin rashes and swollen pancreas when it is taken one a
reagular basis for a long time
Codeine
Causes addiction, drowsiness, trouble sleeping, irregular heartbeat and hallucinations
Medicine
Chapter 5 Chemicals For Consumers
Side effects of antibiotics
All the antibiotic dosage prescribed by the doctor must be consumed.
This is to ensure that all the bacteria are killed.
If not, the surviving bacteria will multiply and mutate.
This will require a higher dosage of the same antibiotic to counter the same
bacteria if the person is infected by the same strain of bacteria.
Penicillin
•
Causes allergic reaction, diarrhoea, difficulty breathing & easily bruising
Streptomycin
•
Causes injury to the kidney & nerve damage that result in deafness
Tetracycline
•
Causes stomach cramps, watery diarrhoea, skin reaction to sunlight & fewer
Medicine
Chapter 5 Chemicals For Consumers
Side effects of psychotherapeutic medicines
All psychotherapeutic medicines can cause dependency if taken for prolonged period of time.
Antipsychotherapeutic medicines
Causes drowsiness, rapid heartbeat dizziness
Antidepressants include:
Barbiturates
Causes addiction, anxiety, dizziness, hallucinations, increase dreaming
Stimulants
Causes addiction, insomnia, weight loss due to loss of appetile
Tranquilizers
Causes addiction, respiratory difficulties, sleeplessness, coma & death
Side effect of steroids
Prolonged use of steroid can cause increase of body weight and blood pressure,
blindness, joint pain and muscle spasm.
The End