Chemistry Folio Form 5 Chapter 5 Chemicals for Consumers

7/23/2019 Chemistry Folio Form 5 Chapter 5 Chemicals for Consumers

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Chemicals For Consumers 2013

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CONTENTS

PAGEIntroduction 35.1 Soap and Detergent

5.1.1 The History Of Soap Manufacturing5.1.2 Preparation Of Soap By Saponification

How to prepare soap by using saponification in thelaboratory

5.1.3 Types Of Soap5.1.4 Detergents

Preparation Of Detergents5.1.4a The Structure Of Detergent Molecule5.1.4b The Cleansing Action Of Soap And Detergent5.1.4c Additives In Detergents5.1.5 The Effectiveness Of Soaps And Detergents As Cleansing

Agents

45

6-78

9101112

13-141516

5.2 Food Additives5.2.1 Effect Of Food Additives On Health

17-2223

5.3 Medicines 24-265.4 The Existence Of Chemicals 27Conclusion 28


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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 ofliving. 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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5.1.1 THE HISTORY OF SOAP MANUFACTURING


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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)

(Vegetable oils: Palm oil/Olive oil)


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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 saponi fi cation 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 ove

a glass rod and filter the

contents of the beaker.

After filtration, soap is lef

behind in the filter paper.


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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 toi let 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, C15H31COONab) 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 fr action.Thus, detergents are

petrochemicals.

Detergents

Anionic detergents

where the head ofthe detergent particle

contains anegatively chargedion.

R

O

SO3-Na+

(Sodium alkyl sulphate)

Cationic detergents

Cationic detergents wherethe head

of the detergent particle

contains apositively chargedion.

R N (CH3)3+BR-

Non ionic detergent

R O CH2CH2OH

Further divided into


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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 isdidecan 1ol, CH3(CH2)10CH2OH

Detergent prepared from dodecan1olis called sodium dodecyl sulphate /

sodium lauryl sulphate

CH3(CH2)10CH2O-SO3-Na

+


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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+) anddetergent ions. The detergent ions have the same basic structure as the soap ions, thatis 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)

so3

-

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 theirchemical 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. Thiscause 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 ofdetergent 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 whitefabrics.

Fluorescent dyes

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

Carboxymethylcellulose(CMC)

Biological enzymes -To remove protein stains such as blood.

-To break down fat and protein molecules infood stains.

Amylases ,proteases,

cellulases and lipases

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

Sodium perborateSodium hypochlorite

(NaClO)


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5.1.5 THE EFFECTIVENESS OF SOAPS AND

DETERGENTS AS CLEANSING AGENTSCleansing

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 bedecomposed by the action of bacteria.

1. Ineffective in hard water.

2. A grey scum (Magnesium stearate &

calcium stearate) will be produced in hardwater.

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 acidmolecules of large molecular size that are

insoluble in water. Example,

Detergent 1. Effective in soft water and hard water.

( magnesium salt and calcium salts areformed 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 isnot combining with detergent ions.

1. Non-biodegradable

2. Water pollution occurs.

3. Decrease in oxygen content in water and

the aquatic lives are given theharm.( phosphates in detergents)

4. a lot of foam will be produced in water

that prevent oxygen from dissolving inwater. As a result, fish and other aquatic

lives face the death.

5. Additives (sodium hypochlorite) releaseschlorine 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 offood.

Food additives are chemicals that are added to food in small quanti ties for

specif ic purposes such as protection against bacter ial attack or restoring the

colour of food destroyed dur ing 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 Groupof 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)

Azo compounds ; tripheny compounds


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I. PRESERVATIVES

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

the growth of microorgani sm such as bacter ia, mould or fungus, so thatthe 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 preventbrowning in fruit juices.

Maintain the colour and freshness ofvegetables.

To prevents the growth of yeast


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II. ANTIOXIDANTS

Antioxidants are chemicals that are added to foods to prevent the

oxidation of fats and oils by oxygen i n 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. F lavour enhancer have li ttle 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 thesweetness 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

Flavour Strawberry Orange Pineapple


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IV. STABILISERS & THICKENING AGENTS

Stabilisers and thickening agentsimprove the texture and the blending of

foods.

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

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

Examples of stabili zers are gelatin and acacia gum.

1. Stabilisers are added to improve the texture of foods. For examples, stabi li sers are

added to i ce-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 thi cken the

liquid and to prevent the foods fr om becoming liquid. Thickening agents

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

produce a jell y-like structure.

1. Most thickening agents are natural carbohydrates. Gelatin and pectin are added to

help jams and jellies to set.

Thickeners ExplanationModified 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.

Gelatine To thicken yogurt.


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V. DYES

Dyes (colouring agents) arechemicals 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

in colour.


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5.2.1 EFFECT OF FOOD ADDITIVES ON HEALTH

Effects ExplanationAllergy 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 iitssynptoms 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

nutritionalvalue

Medical reasons

Life without food

additives

Food

spoilage

always

occurDiseases will

occur often

Malnutrition

will occur


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5.3 MEDICINES

A medicine is a substance used to pr event or cure diseases or to reducepain and suf fer ing due to il lnesses.

It is classified as;

a. Traditional Medicines

Traditional medicines are medicines derived from natural sources such as plants andanimals 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 keepthe 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 theskin

For preventing flu attack

For treating skin diseases

Quinine Bark of Chinchona

tree

For treating malaria

For preventing muscle crampsGinseng 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 antifungalproperties

For treating cough


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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, anti biotics, psychotherapeuti cdrugs.

Modern medicines usually contain a mix ture of active ingredients prepared in

dif ferent forms, such as capsul es, pi l ls, solu tions or suspensions.

Type Example Function Side Effects

ANALGESICSTo relieve pain

without causingnumbness/affectin

g conciousness

Aspirin Used for painrelief such as

arthritic painand dental

pain

- Cause internalbleeding and

ulceration- Can cause

brain and liverdamage if

given tochildren with

flu/chickenpox

Paracetamol Used forrelieve mild

to moderatepain such as

headache,muscle and

joint pain

- If overdose, itcan cause

liver damage

Codeine Used in

headachetablets and in

coughmedicines

- Can causedrowsiness

- If overdose, itcan lead toaddiction,

depression andnausea

ANTIBIOTICSTo kill/slow down

the growth ofbacteria

Penicillin Used to curetuberculosis

andpneumonia

- headache,allergic

reaction,diarrhoea


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Streptomycin

PSYCHOTHERA

PEUTIC DRUGS

To alter abnormalthinking, feelings

and behaviors

StimulantEg: Methylpenidate

To reducefatigue and

elevate mood

- If overdose,can lead to

anxiety,hallucinations

and severedepression

AntidepressantEg: Tranquilisers

Eg: Barbiturates

To reducetension and

anxiety

- Drowsiness,poor

coordination- If overdose,

can lead torespiratory

problems,coma and even

death

- Addiction- Can lead to

involuntary

death

especially forpeople whoused it to fight

againstinsomnia


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5.4 THE EXISTENCE OF CHEMICALS

The chemicals for consumers such as soap, detergents , food additives andmedicine 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 doctors instruction for taking medicine .

Keep away from children .

Do not overdose .


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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 andintensive scientific research must be carried out to produce new substances and thistakes more time . Scientists must patient and persevere for their research and

development to produce new chemicals in future .

Chemistry Folio Form 5 Chapter 5 Chemicals for Consumers

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Transcript of Chemistry Folio Form 5 Chapter 5 Chemicals for Consumers