Folio Chemistry Form 5 - Chemicals for Consumers

CHEMICALS FOR CONSUMERS

LUQMAN NAiM B. MOHD ESA

5 SAGA

No. TITLE PAGE1. Soaps & Detergents 3

Intro 4 Soaps

- History of Soap Manufacturing- Preparation of Soap Manufacturing- Structure of Soap Molecule

5567

Detergents- Preparation of Detergents- Structure of Detergent Molecule- Cleansing of Soap & Detergent- Additives in Detergent- Effectivesness of Soaps & Detergents

89-1010

11-1213-1415-16

2. Food Additives 17 Uses of Food Additives

- Types of Additives & Examples- Functions of Food Additives- Effects of Food Additives

1818

19-2121-22

The Rationale for using Food Additives 22-233. Medicines 24

Sources & Uses of Traditional Medicines 25 Modern Medicines

- Functions of each type of Modern Meds26

26-28 Side Effects of Traditional Medicines 29 Side Effects of Modern Medicines 29 Correct Ways of Using Medicines 30

SOAPS & DETERGENTS

INTRODUCTION1. Cleansing agents are chemical substance used to remove grease and dirt.2. There are two type of cleansing agents :

a) Soaps

b) Detergents3. Soaps are sodium or potassium salt of fatty acids that contains 12 to 18 carbon

atoms per molecule.4. Soaps are cleansing agents made from animal fats or vegetable oil by

saponification.

Soap is a salt of a compound known as a fatty acid. A soap molecule consists of a long hydrocarbon chain (composed of carbons and hydrogens) with a carboxylic acid group on one end which is ionic bonded to a metal ion, usually a sodium or potassium. The hydrocarbon end is nonpolar and is soluble in nonpolar substances (such as fats and oils), and the ionic end (the salt of a carboxylic acid) is soluble in water. The structure of a soap molecule is represented below:

O ||

CH3-CH2-CH2- CH2-CH2-CH2-CH2- CH2-CH2- CH2-CH2- CH2-CH2- CH2-CH2- C-O− Na+

Non-polar hydrocarbon chain ionic end.(Soluble in nonpolar substances) (Soluble in water)

Detergents are structurally similar to soaps, but differ in the water-soluble portion. Three examples of detergents are shown below.

SOAP

sodium alkyl sulfate

sodium alkylbenzene sulfonate

The History of Soap Manufacturing1. Soap have been used for more than 3000 years. It was recorded that the

Babylonians were making soaps around 2800 B.C.

2. The ‘Purifying Oils’ were recorded on Hebrew tablets in 4000 B.C.

3. In ancients time, soap made from ashes of plants which contain sodium carbonate and potassium carbonate. The ashes were boiled with lime (calcium oxide) to produce caustic potash (potassium hydroxide). Caustic potash is then boiled with the animal fats to produce soap.

a) Ash + Lime boiled Caustic Potash(K2CO3) (CaO) (KOH)

b) Caustic Potash + Animal Fats boiled Soap

4. In 1861, the Belgian Chemist Ernest Solvay (1838-1922) discovered the process to make soda (sodium carbonate) from common salt (sodium chloride) and calcium carbonate.

5. This process is known as the Solvay Process which produces sodium carbonate cheaply for industrial use. Sodium carbonate (often called soda or soda ash) is used for making glass, soaps and detergents.

6. Michel Chevreul (1786-1889), a French chemist, was noted for his research in the composition of animal fats is composed of fatty acids and glycerol. This discovery contributed to the rapid development of the soap and candle industry.

Preparation of soap by saponification 1. Soap is a cleansing agents produced by the reaction between sodium hydroxide

and potassium hydroxide with animal fats or vegetable oils. This reaction is known as saponification.

2. Fats and vegetable oils are large, naturally occurring ester molecules. When fats or oils are boiled with concentrated alkalis, such as sodium hydroxide,

saponification occurs and the ester molecules are broken down into soap and glycerol.

Fats or vegetable oils + concentrated alkalis soap +glycerol

3. Saponification is the alkaline hydrolysis of ester using alkali solutions. From the chemist aspect, soaps are sodium salts or potassium salts of long chain carboxylic acids (with 12 to 18 carbon atoms per molecule).

4. Some examples of soaps are shown below.a) Sodium palmitate, C15H31COONab) Sodium oleate, C17H33COONac) Sodium stearate, C17H35COONa

Additives such as perfume, colouring matter and sometimes antiseptics are added to soaps to enhance their marketability.

5. Glyceryl tristearates are naturally occurring esters commonly found in animal fats and vegetable oils. When the ester is boiled with concentrated sodium hydroxide solution, saponification (alkaline hydrolysis) occurs and mixture of sodium stearate (soap) and glycerol is obtained.

CH2COOC17H35 CH2OH

CHCOOC17H35 + 3NaOH CHOH

(heating)

CH2COOC17H35 3C17H35COONa + CH2OH

Glyceryl tristearate Sodium stearate (soap) Glycerol

6. The soap produced can be precipitated by adding common salt (sodium chloride) to the reaction mixture.

7. The sodium chloride added reduced the solubility of soap in water. As a result, precipitation of soap occurs.

8. The properties of soap depend on :a) The type of alkali used for saponificationb) The type of animal fats or vegetable oils used.

9. Soaps produced from sodium hydroxide are hard, whereas soaps produced from potassium hydroxide are soft.

10. Animal fats (tallow) from cows and vegetable oils (such as palm oil or olive oil) ae used for making soap.

The structure of soap molecule1. 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)

2. 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.

3. 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.

4. Soaps made from palmitic acid are known as sodium palmitate. Figure 5.2 shows the structure of the palmitate ion in soaps.

5. 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.

(a) The molecular model of the palmitate ion.

(b) The diagrammatic representation of the soap ion.

DETERGENTS1. Detergents are synthetic cleansing agents made from hydrocarbons obtained from

petroleum fractions. Thus, detergents are petrochemicals. 2. 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.Negatively charged ion

O

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

3. 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 :

b) Detergent molecule without a benzene ring such as sodium alkyl sulphate.We can represent the detergent ion, alkyl sulphate ion as:

R – OSO3

Preparation of detergents

1. The detergent, sodium alkyl sulphate can be prepared from alcohols with chain lengths of 12 to 18 carbon atoms in two steps.

Steps 1: Reaction with concentrated sulphuric acid

Positively charged ion

Step 2: Neutralisation with sodium hydroxide solution.

2. 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+ .3. 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.

a) Step 1 : Alkylation

Alkylation is the introduction of the alkyl group to an organic molecule.

b) Step 2 : SulphonationAlkylbenzene produced the react with concentrated sulphuric acid acid to form alkylbenzene sulphonic acid.

Sulphonation is the introduction of the sulphonic acid group, -SO3H to an organic molecule to form sulphonic acid.

c) Step 3 : Neutralisation

Alkylbenzene sulphonic acid produced reacted with sodium hydroxide to form sodium alkylbenzene sulphonate, the detergent

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).

alkyl sulphate ion

Alkylbenzene sulphonate ion

The cleansing of soap and detergent

1. The cleansing action of soap or detergent depends on their chemical bonding and structures.

a) The ionic ‘head’ (negatively charged) is soluble in water (hydrophilic) but insoluble in oily layer.

b) The long hydrocarbon ‘tail’ (neutral) is insoluble in water (hydrophobic) but soluble in oily layer.

2. Oil cannot be washed away from clothing with water because oil (a covalent molecult0 is insoluble in water.

3. 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.

4. I 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.

The cleansing action of soap

5. On further agitation during washing, the greasy dirt is lifted from the surface.

6. Emulsifying dirt in watera) 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

Additives in detergents1. 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 (Na5P3O10)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 perboratea) 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 proteasea) 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. Brightenersa) Figure below shows the action of brighteners. The brighteners absorb the

invisible ultra-violet and re-radiate it as blue light.

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 silicateAnhydrous 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. Stabilisersa) 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. PerfumesPerfumes are added to make clothes smell fresh and clean.

The effectiveness of soaps and detergents as cleansing agents

Advantages of soaps

1. Soaps are effective cleansing agents in soft water, that is water does not contain Mg2+ and Ca2+ ions.

2. Soaps do not cause pollution problems to the environment. This is because soaps are made from chemical found in animals and plants. This means that soaps are biodegradable, that is they can be composed by the action of bacteria.

Disadvantages of soaps 1. Soaps are ineffective in hard water, that is, water that contains magnesium and

calcium salts.2. In hard water, soaps will react with Mg2+ and thus, soaps do not lather in hard

water.3. Scum is grey solid that is insoluble in water. It consists of magnesium stearate and

calcium stearate.4. Soaps are not also effective in acidic water, for example rainwater containing

dissolves acids. H+ ions from acids will react with soap ions to produce carboxylic acids molecular size that are insoluble in water.

5. Stearic acids and other carboxylic acids do not act as cleansing agents because they exist mainly as molecules and do not anionic hydrophilic ends (’head’) that dissolves in water.

Advantages of detergents1. Detergents are cleansing agents that are effective in soft water as well as hard

water. This is because detergents do not form scum with Mg+ and Ca2+ ions found in hard water.

2. The detergents ions (R –O – SO3- and R – SO3

- )react with Mg+ and Ca2+ ions in hard water. However, the magnesium salts and calcium salts which are formed are soluble in water. Hence, the scum is not formed and the detergents are still active in hard water and lathers easily.

3. Detergents are synthetic cleansing agents. This means that the structure of the hydrocarbon chain can be modified to produce detergents with specific properties. Nowadays, different types of detergents have been synthesised for specific uses such as shampoos and dish cleaner.

4. Furthermore, detergents are also effective in acidic water because H+ ion is acidic water do not combined with detergents ions.

Disadvantages of detergents1. Most detergents have branched hydrocarbon chains and are non-biodegradable,

that is, they cannot decomposed by bacteria. As a result, non-biodegradable detergents cause water pollution.

2. Phosphates in detergents act as fertilizers and promote the growth of water plants and algae. When the plants die and decay, they will used up the oxygen dissolves

in water. This will decrease the oxygen content in water and kill fishes and other aquatic lives.

3. Detergents produce a lot of foam in water. The layer of foam that covers the water surface will prevents oxygen from dissolving in water. This condition will cause fish and other aquatic life ti die from oxygen starvation.

4. Additives such as sodium hydrochlorite (bleaching agents) releases chlorine gas in water that is acidic. Chlorine gas is highly toxic and kills aquatic life.

FOOD ADDITIVES

USES OF FOOD ADDITIVES

Types of additives and examples 1. 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.

2. 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.

3. Food additives are used :a) To retard food spoilage and to preserve food (longer shelf life).b) To make food taste better or smell better.c) To add colouring to food so that the food looks fresher, more interesting

or more appealing.

4. There are two main groups of food additives :a) Preservatives and antioxidants to protect food from being spoiled by

bacterial attact or atmospheric oxidation. In this way, the food can be kept longer.

b) Flavouring agents, stabilizers, thickening agents (thickeners), and dyes (colouring agents) to enhance the taste, smell and appearance of the food.

5. Table below show a list of different types of food additives, their functions and examples of each types.

Type of food additive Examples of food additivePreservatives Sodium nitrite ; sodium nitrate ; benzoic acid ; sodium benzoate ;

sulphur dioxide ; sodium sulphite ; sorbic acid ; sodium sorbateAntioxidants Ascorbic acid (vitamin C) ; BHA (butylated hydroxyanisole) ; BHT

(butylated hydrixitoluene) ; citric acid ; sodim citrateFlavouring agents Monosodium glutamate (MSG) ; aspartameStabilisers and thickening agents

Gelatin ; acacia gum (agar)

Dyes (colouring agents)

Azo compounds ; tripheny compounds

Functions of food additives

Preservatives1. 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.

2. 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.

3. 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.

Preservative Molecular formula Uses Sodium nitriteSodium 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 freshBenzoic acidSodium benzoate

C6H5COOHC6H5COONa

To preserve sauce (olyster, tomato or chilli), fruit juice, jam and margarine

Sulphur dioxideSodium sulphite

SO2

Na2SO3

Used as bleaches and antioxidants to prevent browning in fruit juices.

Maintain the colour and freshness of vegetables.

To prevents the growth of yeast

Antioxidants1. Antioxidants are chemicals that are added to foods to prevent the oxidation of fats

and oils by oxygen in the air.

2. Foods containing fats or oils are oxidized and become rancid when exposed to air.

3. 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).

4. 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.

Flavouring agents

1. There are two types of flavouring agents : artificial flavours and flavour enhancer. They are added to foods to make them taste better.

2. 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.

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

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

5. 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.

6. 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

Stabilisers and thickening agents1. Stabilisers and thickening agents improve the texture and the blending of foods.2. 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.

3. 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.

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

5. 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.

6. 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.

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

Dyes

1. Dyes (colouring agents) are chemicals that are added to foods to give them colour so as to improve their appearance.

2. 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.

3. 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.

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

5. 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.

Effect of food additives on health1. The types of food additives allowed and the quantity permitted are controlled by the

1983 Food Act and the 1985 Food Regulation.2. The permissible quantity depends on the type of food and the food additives. For

example, benzoic acid added must not exceed 800 mg per kg in cordial drinks, whereas sodium nitrite must not exceed 100 mg per kg in meat product.

3. The excessive intake of food additives for a prolonged period of time will ruin our health. The side effects arising from taking food additives are allergy, cancer, brain damage and hyperactivity.

4. Allergy a) Food additives such as sodium sulphite (preservative), BHA and BHT

(antioxidants), MSG (flavouring) and some food colours (e.g, Yellow No. 5) can cause allergic reactions in some people.

b) The symptoms of MSG allergy are giddiness, chest pain and difficulty in breathing. This condition is called the ‘Chinese restaurant syndrome’

c) The presence of sodium nitrate or sodium nitrite in food can cause ‘blue baby’ syndrome that is fatal for babies. This syndrome is due to the lack of oxygen in the blood. Hence, the use of nitrate and nitrite is allowed in baby foods.

5. Cancer

a) Chemicals that cause cancer are called carcinogens. Sodium nitrite (a preservative) is a potent carcinogen.

b) The nitrite react with the amines in food to produce nitrosamine which can cause cancer.

6. Brain damage Excessive intake of nitrites for a prolonged period of time can cause brain damage. In this condition, the supply of oxygen to the brain is disrupted and this cause brain damage.

7. Hyperactivity a) Food additives such as tartrazine can cause hyperactivity.b) Children who are hyperactivity become very active, find it difficult to relax or

sleep and are very restless.

The rationale for using food additives

Advantages1. To prevent food spoilage

a) Oxidation and microorganism (bacteria, fungi) are the main causes in the decomposition of food. In hot climate, meat and fish rot easily. The use of preservatives is an effective way to prevent food spoilage and to ensure that foods can be supplied throughout the year.

b) If preservative are not used, food spoilage might drastically reduce the food supply, making foods to cost more.

c) Few deaths are associates with the use of food additives. However, many people die due to food poisoning caused by bacterial toxins.

2. To improve nutritional valueDuring food processing, vitamins and minerals may be destroyed. Thus, additives that improve nutrition can be added. These additives include vitamin B, C and D, and minerals such as iron. The addition of these additives increase the nutritional value of foods.

3. For medical reasonsa) Aspartame and sorbitol are used to make foods and drinks sweet without

using sugar. These food additives are particularly useful as artificial sweeteners for diabetic patients.

b) Artificial sweeteners give the sweet taste but without adding calories to the food. Thus, they can be used to reduce obesity.

c) Potassium iodide is added to table salt to reduce the incidence of goitre.d) Vitamin C is added to friut juices to prevent scurvy. Vitamin D is added to

margarine to prevent rickets.

Disadvantages

1. Eating food additives such as preservatives, antioxidants and flavour enhancers is excess quantities over a long period of time is detrimental to health.

2. Some food additives are used to make foods look more appealing. These additives have little nutritional value. Eating such foods increases the risk of health hazard.

3. Some foods are fortified with excess amounts of nutrients, such as vitamins A and D, or of trace elements, such as copper and zinc. Eating foods with excessive amounts of nutrients can ruin our health.

MEDICINES

Sources and uses of traditional medicines

1. A medicine is a substance used to prevent or cure diseases or to reduce pain and suffering due to illnesses.

2. Traditional medicines are medicines derived from natural sources such as plants and animals without being processed chemically.

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

4. 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

pressureGinger 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 attackAloe 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

For treating coughTongkat Ali Roots As a tonic for after a birth and

general health

Modern medicines1. Before the 20th century, most medicines were extracted from plants (herbal

medicines). Since 1900. Thousands of modern drugs have been synthesised from organic compound.

2. Modern medicines can be classified as follows based on their effects on the human body.

3. Some examples of modern medicines are analgesics, antibiotics, psychotherapeutic drugs.

4. Modern drugs have a trade name and a generic name. For example, the analgesic aspirin (generic name) is sold under different brand names such as Caprin and Disprin. Similarly, paracetamol (generic name) is sold under the trade name of Panadol.

5. Modern medicines usually contain a mixture of active ingredients prepared in different forms, such as capsules, pills, solutions or suspensions. For example, Alka-Seltzer (used as an antacid) contains sodium bicarbonate (NaHCO3), citric acid and aspirin. It is the sodium bicarbonate then neutralizes the excess stomach acid.

Fucntion of each type of modern drugAnalgesics

1. Analgesics are medicines that relieve pain. Examples of analgesics are aspirin, paraccetamol, and codeine. Analgesics are sometimes called painkillers.

2. Aspirin and paracetamol are mild painkillers whereas codeine is powerful painkillers.3. Analgesics relive pain but do not cure the disease.4. Aspirin : pain relief and anti-inflammatory action

a) The IUPAC name of aspirin is acetyl aslicylec acid. Aspirin contains two functional groups, a carboxylic acid group and the ester group. Thus, aspirin is aicidc in nature.

b) Uses of aspirinAspirin reduces fever and inflammable as well as relives pain. Aspirin is used to :(i) Reduce fever

(ii) Relieve headaches, muscle aches and joint aches(iii) Treat arthritis, a disease caused by inflammation of the joints(iv) Act as an anticoagulant. It prevents the clotting of blood and reduce the

risk of the heart attack and strokes.5. Paracetamol

a) Paracetamol have the following structural formula. Thus, unlike aspirin, paracetamol is neutral in nature.

b) Paracetamol is similar to aspirin in its effects (that is, reduces fever and relieves pain) but it does not reduce inflammation.

c) Paracetamol also reduces or relieves flu symptoms such as fever, bone aches and runny nose.

6. Codeinea) Codeine is an organic compound that contains the elements of carbon,

hydrogen, oxygen and nitrogen.b) Codeine is an analgesics and is used to relive mirror to moderate pain.

Codeine is more powerful than morphine. Codeine and morphine are narcotic drugs

c) Codeine is also used in cough mixtures for suppressing coughs.

Antibiotics : antibacterial medicine

1. Antibiotics are chemicals that destroy or prevent the growth of infectious microorganism.

2. Two examples of antibiotics are penicillin and streptomycin.3. Antibiotics are used to treat diseases caused by bacteria.4. Antibiotics are not effective against diseases caused by viral infections such as

influenza, measles, or small pox.5. Penicillin

a) Penicillin is derived from the mould Penicillium notatum.b) Penicillin are used to treat diseases, caused by bacteria, such as pneumonia,

gonorrhea and syphilis.c) Penicillin is only effective on certain bacteria. For example, it cannot be used

to treat tuberculosis.6. Streptomycin is the antibiotic that is effective in treating tuberculosis.

Psychotherapeutic medicines

1. Psychotherapeutic medicines are a group of drugs for treating mental or emotional illnesses.

2. Psychotherapeutic drugs can be divided into a few groups as shown in table below :

Types of psychotherapeutic drugs

Example

a) Stimulants Caffeine, amphetamineb) Antidepressant Prozacc) Antipsychotic

agentsChloropromazin

3. Stimulantsa) Stimulants are naturally occurring or synthetic drugs that stimulate (excite) the

activity of the brain and central nervous system.b) Adrenaline is a stimulant that the body produces when it needs to prepare for

demanding or energetic activities.c) Stimulants make a person more alert, more energetic, less tired and more

cheerful.d) Examples of stimulants are caffeine and amphetamines. Caffeine is a week,

naturally occurring stimulant and is found on coffee, tea and Cola drinks.e) Amphetamines are strong synthetic stimulants and increase alertness and

physical ability.f) Amphetamines increase the heart and respiration rates, as well as the blood

pressure. As a result, it causes the body to postpone the need of sleep and can reverse, partially and temporarily, the symptoms of fatigue.

4. Antidepressantsa) Depression is a chronic illness. Most cases of depression are caused by a

chemical imbalance in the brain.b) People experiencing depression feel hopeless. They experience a loss of

interest in everyday activities such as work or hobbies.c) There is a strong correlation between the amounts of special chemicals (called

neurotransmitters) in the brain and a person’s mood. If these chemicals get too low, the person may feel depressed.

d) Antidepressants are medicines that increase the brain’s level of neurotransmitters, thus improving mood.

e) Antidepressants make a person feel calm and sleepy.

5. Antipsychotic medicinesa) Psychosis is the serious mental illness in which people lose touch with reality.

People with psychosis may, Hear voice and see things that are not really there (hallucinations) Have belief that are not based on reality (delusions)

b) In psychiatry, there are a number of disorders that are classified under ‘ psuchosis’, such as schizophrenias (madness), psychotic depression, mania and so on.

c) Psychotic patients have extreme mood swings. Their mood changes rapidly from high spirit to deep depression.

d) Antipsychotic medicines do not cure symptoms to help the person live a more normal life.

Side effects of traditional medicines

1. It is generally believed that traditional medicines have little side effects compared to modern medicines. In fact, traditional medicines are sometimes used to counteract the side effects of some modern medicines.

2. However, taking high doses of quinine for a prolonged period may cause hearing loss. German health officials recently reported 40 cases of liver damage which were linked to the herbal medicine containing kava-kava.

3. While the use of traditional medicine is rising globally, health experts have insufficient data about how it affects patients.

4. The World Health Organisation( WHO) hopes to set up a global monitoring system to monitor the adverse side effects of traditional medicines.

Side effects of modern medicines

Type of modern drug

Side effects

Aspirin Can cause bleeding in the stomach because aspirin is vey acidic. Can cause allergic reactions, skin rashes and asthmatic attacks

Amphetamines

People who abuse amphetamines are excitable and talkative. Psychologically additive and can cause heart attack. Can cause anxiety, sleeplessness, aggressive behavior and decrease

appetite. Can cause enlarged pupils, heavy perspiration and trembling hands.

Codeine Can cause addiction.

Penicillin Can cause allergic reactions. Can cause death for people who are allergic to it.

Streptomycin Can cause nausea, vomiting, dizziness, rashes and fever. Can cause loss of hearing following long-term use.

Stimulants Can cause addiction.

Antidepressants Can cause addiction. Can cause headaches, grogginess and loss of appetite.

Antipsychotic drugs

Can cause dry mouth, blurred vision, urinary retention, constipation. Can cause tremor and restlessness. Sedation (make people calmer, or to make people sleepy)

Correct ways of using medicines

In taking any medicine, we should know why the medicine is prescribed, how the medicine should be used, what special precautions should be followed, what special diet should be followed, what are the side effects, and what storage conditions are needed. In addition, we should note the following points :

1. Self-medication Do not prescribe medicines for yourself (self-medication) or for other people. Discuss with your doctor and listen to him concerning the medicine to be taken.

2. Follow the instructions given Follow the instructions given by your doctor or pharmacist concerning the dosage and method of taking the medicine.

3. Medicines for adult and children Medicines for adult should not be given to children and vice versa.

4. Side effects Visit the doctor immediately if there are symptoms of allergy or other effects of the drugs.

5. Expiry date Like foods, medicines also have expiry date. Do not take medicines after their expiry dates.