Chemistry Folio Form 5 Chapter 5 Chemicals for Consumers

Form 5

Chapter5

Chemicals for Consumers

Name: Nur Amirah Akmal Binti Kamal Aris

Class: 5 Al-Abqari

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CONTENTS

PAGE

Introduction 3

5.1 Soap and Detergent

5.1.1 The History Of Soap Manufacturing 5.1.2 Preparation Of Soap By Saponification

 How to prepare soap by using saponification in the laboratory

5.1.3 Types Of Soap 5.1.4 Detergents

 Preparation Of Detergents

5.1.4a The Structure Of Detergent Molecule

5.1.4b The Cleansing Action Of Soap And Detergent 5.1.4c Additives In Detergents

5.1.5 The Effectiveness Of Soaps And Detergents As Cleansing Agents 4 5 6-7 8 9 10 11 12 13-14 15 16 5.2 Food Additives

5.2.1 Effect Of Food Additives On Health 17-22 23

5.3 Medicines 24-26

5.4 The Existence Of Chemicals 27

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INTRODUCTION

Chemistry is the science of matter. All objects that exist around us are made of

chemical substances. Without chemistry, life itself would be impossible. All

objects contributed an endless of benefits to mankind. As time continued to

unravel, humans had done their best to delve into this subject to ensure that all the

chemical substances are exploited and utilized to the fullest and simultaneously,

improve the quality of life of mankind.

The discovery of chemicals manufactured for consumers such as cleaning agents,

food additives and medicines has helped us improve our health and standard of

living. Today, different types of chemicals are produced to meet the needs and

preferences of consumers. Therefore, understanding the chemistry of these

chemicals will help a consumer select and use them wisely.

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5.1 SOAP AND DETERGENT

What is soap?

 Soap are sodium or potassium salts

of long-chain carboxylic acids

 The general formula of a soap :

RCOO-Na

+

/ RCOO-K

+

, where R is an

alkyl group which contain 12 to 18

carbon atoms. R can be saturated or

unsaturated.

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5.1.2 PREPARATION OF SOAP BY

SAPONIFICATION

 Soaps are prepared by hydrolysing fats or oils under alkaline

condition. The reaction is called saponification.

Fats/Vegetable oils + Concentrated alkalis → Soap + Glycerol

(Fats: tallow from cow)

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 The soap molecule has two parts: a polar group (-COO-Na+) and a non-polar

group (R-hydrocarbon part).

 The polar group is called the head and the non-polar group is called the tail.

Thus, the soap molecule has a polar head and a non-polar hydrocarbon tail.

 The polar head is hydrophilic in nature (water loving) and the non-polar tail is

hydrophobic (water repelling) in nature.

The saponification reaction is exothermic in nature, because heat is liberated

during the process. The soap formed remains in suspension form in the mixture.

Soap is precipitated as a solid from the suspension by adding common salt to the

suspension. This process is called Salting out of Soap.

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

How to prepare soap by using saponification in the

laboratory

 Take 25 ml of coconut oil in a measuring cylinder and pour it into a 250 ml glass beaker.

 Measure 30 ml of 20% NaOH solution in another measuring cylinder and add it into the beaker containing vegetable oil.

 Then the mixture is stirred vigorously

 Place the beaker on a wire gauze placed over a tripod stand.  Heat the beaker using a Bunsen

burner till the mixture become a whitish paste.

 Remove the beaker from the flame and allow it to cool.

 To the above suspension, add 15g of common salt and stir it well with a glass rod.

 After adding common salt, soap in the suspension gets precipitated out as solid.

 Pour the contents of the beaker into the funnel over a glass rod and filter the contents of the beaker.  After filtration, soap is left

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5.1.3 TYPES OF SOAP

 Depending upon the nature of alkali used in the production of soap, they

are classified into two types.

I.

Hard soap

The sodium salt of long chain fatty acid is known as hard soap. It is difficult to

dissolve in water. It is used as laundry soap.

II.

Soft soap

The potassium salt of long chain fatty acid is known as soft soap, as it produces

more lather. It is used as toilet soap and shaving soap.



In aqueous solution, soap ionises to form alkali ions.

Since soaps have free alkali ions, they are alkaline in nature. Hence, the soap

solutions are slippery to the touch.

Some examples of soaps are shown below.

a)

Sodium palmitate, C15H31COONa

b)

Sodium oleate, C17H33COONa

c)

Sodium stearate, C17H35COONa

 Additives such as perfume, colouring matter and sometimes antiseptics are

added to soaps to enhance their marketability.

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5.1.4 DETERGENT

 Detergent is a synthetic cleansing agents which is made from

hydrocarbons obtained from petroleum fraction.Thus, detergents are

petrochemicals.

Detergents

Anionic detergents

where the head of the detergent particle contains anegatively charged

ion.

R – O – SO3-Na+ (Sodium alkyl sulphate)

Cationic detergents

Cationic detergents where the head

of the detergent particle contains apositively charged

ion.

R – N (CH₃)₃+_BR-

Non ionic detergents

R – O – CH

₂

CH

₂

OH

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

Preparation Of Detergents

Sodium alkyl sulphate

Sodium alkylbenzene sulphonates

-

can be prepared from alcohols with chain

lengths of 12 to 18 carbon atoms.

- Step 1:

Reaction with Concentrated sulphuric acid

Step 2 :

Neutralisation with sodium hydroxide solution

Starting materials

- long chain alkene, RCH = CH , obtained

from the cracking of petroleum.

Step 1 :

Alkylation ( introduction of the alkyl group to

an organic molecule)

Step 2 :

Sulphonation ( introduction of the sulphonic

acid group to an organic molecule to form

sulphonic acid)

Step 3 :

Neutralisation

Alkylbenzene sulphonic acid produced reacted

with sodium hydroxide to form sodium

alkylbenzene sulphonate, the detergent

Example :

 An example of a long chain alcohol is

didecan – 1 –ol, CH

3

(CH

2

)

10

CH

2

OH

 Detergent prepared from dodecan – 1 – ol

is called sodium dodecyl sulphate /

sodium lauryl sulphate

CH

3

(CH

2

)

10

CH

2

O-SO

3

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5.1.4a THE STRUCTURE OF DETERGENT

MOLECULE

 When a detergent is dissolved in water, it dissociates to form sodium ions (Na+

) and detergent ions. The detergent ions have the same basic structure as the soap ions, that is consist of two parts :

a) The ‘head’ is the sulphate group (-OSO3-), which is negatively charged and

hydrophilic (dissolves readily in water but not in oils and grease).

b) The ‘tail’ is the long hydrocarbon chain, which is neutral and hydrophobic (dissolves readily in oils and grease, but not in water).

Hydrophilic ‘head’ Hydrophobic ‘tail’ (Hydrophobic) oso₃ -Ionic ‘head’ (Hydrophilic) Hydrophobic ‘tail’ (Hydrophobic)

so

₃ -Ionic ‘head’ (Hydrophilic)

Figure 5.1.4a - Alkyl sulphate ion

Figure 5.1.4b - Alkylbenzene sulphonate ion

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5.1.4b THE CLEANSING ACTION OF SOAP AND

DETERGENT

The cleansing action of soap and detergent

The cleansing action of soaps and detergent results from



the ability to lower the surface tension of water,



to emulsify oil/ grease and



to hold them in suspension in water

 This can be occurred due to their chemical bonding and the structure.

 Oil cannot be washed away from clothing with water only as it is a

covalent molecule which is insoluble in water.

I. Lifting greasy dirt from the surface cloth. When soap or detergent is added to the

dirty surface of a piece of cloth covered with a layer of oil or grease.

a) The negatively charged ‘head’ (hydrophilic) of soap ions or detergent ions dissolves in water.

b)The hydrocarbon ‘tail’ (hydrophobic) of soap or detergent ions dissolves in the layer of grease.

II. The water is agitated slightly, the grease begins to be lifted off the surface. This cause by the forces of attraction between the water molecules and the negatively charged heads.

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III. On further agitation during washing, the greasy dirt is lifted from the surface. IV. Emulsifying dirt in water

a) Soaps and detergents can act as emulsifying agents to emulsify oils and grease. b) The process of emulsification breaks large drops of grease into smaller droplets that

floats in water. The greasy droplets repel on another because they carry the same charge. As a result, the grease is suspended in the solution.

c) When the cloth is rinsed with the water, the droplet will be carried away.

d) The cleaning process become more efficient in the water containing the soap or detergent solution is stirred

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5.1.4c ADDITIVES IN DETERGENTS

ADDITIVES

FUNCTION

EXAMPLE

Builders -To enhance the cleaning efficiency of detergent by softening the water. -To increase the pH value of water.

Sodium tripolyphosphate

Drying agents -To ensure that the detergent in powdered form is always in dry condition.

-To add to the bulk of the detergent and enable to pour it at ease.

Sodium sulphate Sodium silicate

Fragrances -To add fragrance to both detergent and fabrics.

Foam control agents -To control foaming in detergent.

Optical whitener -To add brightness and whiteness to white fabrics.

Fluorescent dyes

Suspension agents -To prevent dirt particles removed from redepositing onto cleaned fabrics.

Carboxymethylcellulose (CMC)

Biological enzymes -To remove protein stains such as blood. -To break down fat and protein molecules in food stains.

Amylases ,proteases, cellulases and lipases

Whitening agents -To convert stains into colourless substances. -To make the fabrics whiter and more beautiful.

Sodium perborate Sodium hypochlorite (NaClO)

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5.1.5 THE EFFECTIVENESS OF SOAPS AND

DETERGENTS AS CLEANSING AGENTS

Cleansing agents

Advantages Disadvantages

Soap 1. Very effective in soft water to wash clothes.( water does not contain Mg+ & Ca+ ions)

2. Do not cause pollution as soaps are made from fats and oils and can be decomposed by the action of bacteria.

1. Ineffective in hard water.

2. A grey scum (Magnesium stearate & calcium stearate) will be produced in hard water.

3. Not effective in acid water.( exist as molecules & do not have hydrophilic ends) - H ion from rainwater (acid) will react with soap ions to produce carboxylic acid molecules of large molecular size that are insoluble in water. Example,

Detergent 1. Effective in soft water and hard water. ( magnesium salt and calcium salts are formed and soluble in water)

( scum is not formed)

2. Synthetic cleansing agents

- Structure of hydrocarbon chain can be modified to produce detergent.

3. Effective in acidic water as H ions is not combining with detergent ions.

1. Non-biodegradable 2. Water pollution occurs.

3. Decrease in oxygen content in water and the aquatic lives are given the

harm.( phosphates in detergents)

4. a lot of foam will be produced in water that prevent oxygen from dissolving in water. As a result, fish and other aquatic lives face the death.

5. Additives (sodium hypochlorite) releases chlorine gas that is highly toxic and kills aquatic life.

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5.2 FOOD ADDITIVES

 Food preservative have been used since ancient times. Ancient civilization

used salt to preserve meat and fish, herbs and spices to improve the flavor of

food.

Food additives are chemicals that are added to food in small quantities for

specific purposes such as protection against bacterial attack or restoring the

colour of food destroyed during food processing.

Food additives are used :

i)

prevent spoilage

ii)

improve its appaerance , taste or texture

iii)

prevent growth of microorganisms

iv)

prevent oxidation of fats and oils by oxygen in air

v)

restore the colour of food destroyed during food processing.

Two Main Group

of Food

Additives

Preservatives and

Antioxidants

to protect food from being

spoiled by bacterial attact or

atmospheric oxidation.

Flavouring agents,

stabilizers, thickening agents

(thickeners), and dyes

to enhance the taste, smell and

appearance of the food.

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Table below show a list of different types of food additives and examples of each

types.

Type of food additive

Examples of food additive

Preservatives Sodium nitrite ; sodium nitrate ; benzoic acid ; sodium benzoate ; sulphur dioxide ; sodium sulphite ; sorbic acid ; sodium sorbate

Antioxidants Ascorbic acid (vitamin C) ; BHA (butylated hydroxyanisole) ; BHT (butylated hydrixitoluene) ; citric acid ; sodim citrate

Flavouring agents Monosodium glutamate (MSG) ; aspartame

Stabilisers and thickening agents

Gelatin ; acacia gum (agar)

Dyes (colouring agents)

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I. PRESERVATIVES

 Preservatives are chemicals that are added to food to retard or to prevent

the growth of microorganism such as bacteria, mould or fungus, so that

the food can be stored for a long time.

 In ancient times, food additives from natural sources such as salt, sugar and vinegar were used to preserve food and to make the food taste better.

Nowadays, synthetic preservatives are used, table below shows the types of preservatives commonly used. Many of the preservatives are organic acids and salts of organic acids.

Examples;

PRESERVATIVE MOLECULAR FORMULA USES Sodium nitrite Sodium nitrate NaNO2 NaNO3

 To preserve meat, cheese and dried fish.  To prevent food poisoning in canned foods.  To maintain the natural colour of meat and to

make them look fresh Benzoic acid

Sodium benzoate

C6H5COOH

C6H5COONa

 To preserve sauce (olyster, tomato or chilli),

fruit juice, jam and margarine

Sulphur dioxide Sodium sulphite

SO2

Na2SO3

 Used as bleaches and antioxidants to prevent

browning in fruit juices.

 Maintain the colour and freshness of

vegetables.

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II. ANTIOXIDANTS

 Antioxidants are chemicals that are added to foods to prevent the

oxidation of fats and oils by oxygen in the air.

 Foods containing fats or oils are oxidized and become rancid when exposed to air.  When the fats and oils are oxidized, rancid product are formed. This makes the food

unpalatable. The rancid product are volatile organic compound with foul odours (for example , butanoic acid, C3H7COOH).

 Antioxidants are added to fats, oils, cakes, sausages, biscuits and fried foods to slow down the oxidation process so that these foods do not become rancid.

III.

FLAVOURING AGENTS

 There are two types of flavouring agents : artificial flavours and flavour

enhancer. They are added to foods to make them taste better.

1. Flavour enhancer have little or no taste of their own. They are chemicals that are added to food to bring out the flavours or to enhance the taste of food.

2. An example of a flavour enhancer is monosodium glutamate (MSG). MSG is used to enhance the flavours of other foods.

3. Artificial flavour includes sweeteners and other flavours such as peppermint or vanilla. Aspartame and saccharin are examples of artificial sweeteners.

4. Both aspartame and saccharin can be used as a substitute for sugar to enhance the

sweetness in food and drink. However, the used of saccharin is banned in many

countries because it is carcinogenic. Aspartame has largely replaced saccharin as the artificial sweetener or choice.

5. Many esters have fruity odours and tastes and are used as artificial flavours. Table below shows some examples of esters that are used in making drinks.

Ester Benzyl

ethanoate

Octyl ethanoate Ethyl butanoate

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IV.

STABILISERS & THICKENING AGENTS

 Stabilisers and thickening agents improve the texture and the blending of

foods.

 Stabilisers are chemicals that are used to enable oil and water in the food

to mix together properly in order to form an emulsion of oil and water.

Examples of stabilizers are gelatin and acacia gum.

1. Stabilisers are added to improve the texture of foods. For examples, stabilisers are

added to ice-cream and peanut butter to keep them smooth and creamy.

2. In the presence of stabilisers, the emulsion of oil does not separate from water. This means that the stabiliser improves the stability of some foods such as ice-cream and salad dressings (mayonnaise).

3. Without stabilisers, ice crystals would form in ice-cream, particles of chocolate would settle out of chocolate milk, oil and vinegar in salad dressing will separate as soon as mixing is stopped.

 Thickening agents are chemicals that are added to foods to thicken the

liquid and to prevent the foods from becoming liquid. Thickening agents

(also called thickeners) absorb water and thicken the liquid in foods to

produce a jelly-like structure.

1. Most thickening agents are natural carbohydrates. Gelatin and pectin are added to help jams and jellies to set.

Thickeners

Explanation

Modified starch Used in instant soups and puddings.

pectin Used in jams and jellies.

Forms a firm jel when there is sufficient sugar in a mixture. Is not digested.

Can be considered as a beneficial and dietary fibre.

Acacia gum To thicken chewing gum, jelly and wine.

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V.

DYES

 Dyes (colouring agents) are chemicals that are added to foods to give them

colour so as to improve their appearance.

1. Some foods are naturally coloured, but the colour is lost during food processing. The foods industry uses synthetic food colours to :

a) Restore the colour of food lost during food processing.

b) Enhance natural colours, so as to increase the attractiveness of foods. c) Give colour to foods that do not have colour.

2. Some dyes are naturally plant pigments while others are synthetically prepared. The synthetic colours used in foods are azo and triphenyl compounds. Both these compounds are organic compounds.

3. The synthetic dyes , brilliant blue, is an example of triphenyl compound. The synthetic dye, tartrazine and sunset yellow are examples of azo compounds.

4. Azo compounds are organic compounds containing the diazo group, - N = N -, and are usually yellow , red, brown, black in colour. Triphenyl compounds are organic

compounds containing three phenyl groups, -C6H5, and are usually green. Blue or purple

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5.2.1 EFFECT OF FOOD ADDITIVES ON HEALTH

Effects

Explanation

Allergy  Caused by Sodium sulphite, BHA and BHT , MSG and food

dyes( yellow No.5).

 Cause an diseases named ‘ Chinese restaurant syndrome’ (giddiness, chest pain and difficulty in breathing)

 Cause ‘blue baby’ diseases occuring on babies which iits synptoms is lacking of oxygen and the presence of sodium nitrate /nitrite.

Cancer  Caused by carcinogens(sodium nitrite)

 Nitrite reacts with amines to produce nitrosamine( cause cancer)

Brain damage  Caused by excessive intake of nitrites. Hyperactivity  Caused by tartrazine (additives)

 Difficul to sleep or relax and felt restles.

 The Rationale for Using Food Additives

Advantages

To prevent food spoilage. To improve nutritional value Medical reasons

Life without food

additives

Food spoilage always occur Diseases will occur often Malnutrition will occur particularly.

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5.3 MEDICINES

 A medicine is a substance used to prevent or cure diseases or to reduce

pain and suffering due to illnesses.

It is classified as;

a. Traditional Medicines

 Traditional medicines are medicines derived from natural sources such as plants and

animals without being processed chemically.

 Since ancients, mankind had used various types of plants and roots, animals and animal part to cure diseases.

Medicines obtained from plants are known as herbal medicines. The sources and uses of some herbal medicines are shown in table below :

Plant Part of the plant used

Uses

Garlic Corm  For preventing flu attack

 For reducing high blood pressure

Ginger Rhizome (horizontal underground stem) and leaves

 For treating stomach pain due to wind in the stomach

 For supplying heat energy to keep the body warm

 For preventing flu attack

Aloe vera Leaves  For preventing itchy skin

 For treating burns (scalding) on the skin

Lemon (lime) Fruits  For treating boils or abscesses on the

skin

 For preventing flu attack  For treating skin diseases

Quinine Bark of Chinchona tree

 For treating malaria

 For preventing muscle cramps

Ginseng Roots  As a tonic to improve the overall

health of human beings

 For increasing energy, endurance and reducing fatigue

Lemon grass Stem/leaves  Has antibacterial and antifungal

properties

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b. Modern Medicines

 Modern medicines can be classified as follows based on their effects on the human body.  Some examples of modern medicines are analgesics, antibiotics, psychotherapeutic

drugs.

 Modern medicines usually contain a mixture of active ingredients prepared in

different forms, such as capsules, pills, solutions or suspensions.

Type Example Function Side Effects

ANALGESICS

To relieve pain without causing numbness/affectin

g conciousness

Aspirin Used for pain relief such as arthritic pain and dental pain - Cause internal bleeding and ulceration - Can cause

brain and liver damage if given to children with flu/chicken pox

Paracetamol Used for relieve mild to moderate pain such as headache, muscle and joint pain - If overdose, it can cause liver damage Codeine Used in headache tablets and in cough medicines - Can cause drowsiness - If overdose, it can lead to addiction, depression and nausea ANTIBIOTICS To kill/slow down the growth of bacteria

Penicillin Used to cure tuberculosis and pneumonia - headache, allergic reaction, diarrhoea

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Streptomycin PSYCHOTHERA PEUTIC DRUGS To alter abnormal thinking, feelings and behaviors Stimulant Eg: Methylpenidate To reduce fatigue and elevate mood - If overdose, can lead to anxiety, hallucinations and severe depression Antidepressant Eg: Tranquilisers Eg: Barbiturates To reduce tension and anxiety - Drowsiness, poor coordination - If overdose, can lead to respiratory problems, coma and even death - Addiction - Can lead to involuntary death especially for people who used it to fight against insomnia

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5.4 THE EXISTENCE OF CHEMICALS

 The chemicals for consumers such as soap, detergents , food additives and

medicine play an important role in our life . However, they can contribute

negative effects to our health and the environment if these chemicals are

not used wisely .

Some proper management of these chemicals :-

Detergents

Wear gloves when working with strong detergents to protect your hands .

Use biodegradable detergents .

Use appropriate amounts of detergents.

Food additives

Be wise when we consume the food with food additives.

Avoid consuming too much salt and sugar .

Avoid foods with additives which you are sensitive to .

Avoid rewarding children with junk food .

Medicines

No self medication .

Do not take medicine prescribed for someone else .

Check for expiry date .

Follow your doctor’s instruction for taking medicine .

Keep away from children .

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CONCLUSION

Without doubt, these chemicals have improved our standards of living. But we

have to remember that these chemicals must be used accordingly not abusively and

intensive scientific research must be carried out to produce new substances and this

takes more time . Scientists must patient and persevere for their research and

development to produce new chemicals in future .