Chemistry Form 5 Chapter 5 Note

A) SOAP & DETERGEN DETERGENT T I) o

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II) II)

Definition of Soap Soap are sodium or potassium salts of long-chain carboxylic acids The general formula of a soap :  RCOO Na /  RCOO K  •  R is an alkyl group which contain 12 to 18 carbon atoms. ato ms.

The The hi histo story of so soap manuf anufaactu cturing ring..

Babylonians made soap around 2800 B.C.

Purifying oils is recorded on Hebrew Tables around 4000 B.C. Ash + Lime – Caustic potash Caustic Potash + fats – soap

Michel Chevreul (French) discovered animal fats are cmposed of fatty acids and glycerol ( Causes rapid development of soap & candle.)

Sodium carbonate Na CO is produced cheaply & used for glass making , soaps and detergent.

Process of making soap ashes or sodium carbonate from common salt is patented by  Nicholas Leblane (French).

After 20 years, Ernest Solvay ( Belgian Chemist) developed Solvay process.

Later on, vegetables oil is used to replace animal fats.

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Solvay Process - Carbon dioxide ( obtained from heating CaCo ) is passed into concentrated NaCl solution which is saturated with ammonia .  NaCl +NH +H O + CO – Na HCO +NH Cl - NaHCO is then heated to obtain soda. 2NaHCO – Na CO +H O +CO .

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III) Preparation of Soap by Saponification Saponification is a process whereby the soaps are prepared by hydrolyzing   fats or oils under alkaline conditions. It is also the alkaline hydrolysis of esters using alkaline solutions. Fats/ Vegetable oils + concentrated alkalis – soap + glycerol (Fats- tallow from cow) ( Vegetable oils – palm oil or olive oil) For example, - Glyceryl tristearates is a naturally occuring esters  found in fats or oils.  CH COOC H CHCOOC H

+

3 NaOH (concentrated alkali)

+

CH OH

CH COOC H (glyceryl tristearate)

3C H COONa ( sodium stearate) Soap

CHOH CH OH (glycerol)

Example of soap, 1) sodium sodium palmit palmitate ate,, C H COONa COONa 2) Sodium Sodium oleate oleate,, C H COONa COONa 3) Sodium Sodium steara stearate, te, C H COONa COONa ♦

♦

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To enhance the soap’s marketability, additives are used such as perfume , colouring matter and antiseptic . Production of soap can be precipitated by adding common salt to the reaction mixture in order to reduce the solubility of soap in water. Properties of soap depends on a) type of of alkali alkali used for for saponif saponificat ication ion b) type of animal animal fats fats or vegetab vegetable le oils used used 2

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Potassium soap are softer, milder than sodium soap which can be used for   bathing.

IV) Structure of soap molecule. • When soap is dissolved in water, it will dissociate and produce sodium ions and carboxylate ions. • The active substances in soap is carboxylate ions which consists two  parts: a) the ‘ Head’ 1. negatively charged 2. contains the – C – O – ion 3. is hydrophilic ( like to dissolves water)

 b) the ‘Tail’ 1. positively charged 2. is a long long hydro hydrocar carbon bon chain chain 3. is hydrophobic ( do not like to dissolves water)

I )Definition of Detergent hydrocarbons Detergent is a synthetic cleasing agents which is made from hydrocarbons obtained from petroleum fraction. It is a kind of  petrochemicals. There are 3 types of detergent which depends on the charge on detergent ion. a) Anionic Detergent. Head of the detergent particle contains a negatively charged ions. Example : R – O – SO Na Divide into two types: Sodium alkylbenzene sulphonate ( detergent molecule with a benzene ring)

R-

- S – O Na

R

SO

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Sodium alkyl sulphate ( without a benzene ring) R – OSO  b) Cationic Detergent Head of the detergent particle contains a positively charged ion. Example : R – N(CH ) Br  c) Non- ionic detergent Example : R –O –CH CH OH II) Preparation of Detergent Sodium alkyl sulphate - can be prepared from alcohols with chain

lengths of 12 to 18 carbon atoms. - Step 1: Reaction with Concentrated sulphuric acid

Step 2 :

Neutralisation Neutralisation with sodium hydroxide solution

Sodium alkylbenzene sulphonates 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 molrcule to form sulphonic acid)

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Sodium alkyl sulphate Example : Dodecan - 1- ol, CH (CH ) CH OH Detergent prepared from dodecan – 1 – ol is called sodium dodecyl sulphate / sodium lauryl sulphate

Sodium alkylbenzene sulphonates Step 3 : Neutralisation

III) The Structure of Detergent Molecule • When a detergent is dissolved in water, it dissociates to form sodium ions and detergent ions. • It consists of two parts: a) the ‘ Head’ (sulphate group, - OSO / sulphonate group - SO) 1. nega negati tive vely ly char charge ged d 2. hydrop hydrophil hilic ic ( like like water water))  b) the ‘Tail’ ( long hydrocarbon chain) 1. neutral 2. hydrop hydrophob hobic ic ( hates hates wate water) r)

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.

1. sodium soap dissolves in water to form soap (-ions) and sodium (+ions). 5

2. Anion consists of a long hydrocarbon chain with a carboxylate group on one end. 3. the hydrocarbon (hydrophobic)soluble in oil/ grease. 4. carboxylate group (hydrophilic) soluble in water. Process of the cleaning action of soap s oap and detergent. • A piece of cloth is stained with grease and then dipped into soap/ detergent water. •

Through this, the wetting ability of water increases.

•

Thus, the surface of cloth is wetted thouroughly. thouroughly.

•

The hydrophobic part of the soap/ detergent anion dissolve in grease while the hydrophilic part is attracted to water molecule.

•

Because of the forces of attraction between water molecules and negatively-charged negatively-charged heads, the grease begins to be lifted off the surface when the water is agitated slightly.

•

Mechanical agitation during scrubbing helps the process of  emulsfication occurs whereby the grease is broken into small s mall droplets.

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The droplets do not coagulate and redeposit on the surface of  the cloth due to the repulsion between the negative charges on th surface. These droplets are suspended in water to form emulsion. The droplets is rinsed and washed away and leave the surface clean.

IV) Additives in detergents Additives in detergent is used to increase their cleaning power and make the detergent more attractive and saleable.

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Additives

Function

Example

Builders

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

Sodium tripolyphosphate

Drying agents

To ensure that the detergent in powdered form Sodium sulphate is always in dry condition. Sodium silicate To add to the bulk of the detergent and enable to  pour it at ease. To add fragrance to both detergent anf fabrics.

Fragrances Foam control agents

To co control foaming in detergent.

Optical whitener

To add brightness and whiteness to white fabrics. To pr prevent dirt particles removed from redepositing onto cleaned fabrics.

Fluorescent dyes

Biological en enzymes

To re remove pr protein st stains su such as as bl blood. To break down fat and a nd 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)

Suspension ag agents

Carboxymethylcellulose (CMC)

V) The effectiveness of soaps and detergents as cleansing agents Cleansing agents Soap

Advantages

Disadvantages

1. very effective in soft water to wash clothes.( water does not contain Mg & Ca ions) 2. Do not cause pollution po llution 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 stearate & calcium stearate) will be produced in hard ha rd water.

3. Not effective in acid water.( exist as molecules & do not have hydrophilic ends) - H ion from rainwater (acid) will will react 7

with soap ions to produce carbox ylic 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 aand soluble in water) ( scum is not formed)

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 aqua tic lives face the death. 5. Additives (sodium hypochlorite ) releases chlorine gas that is highly toxic and kills aquatic life.

2. Synthetic cleansing agents - structure of hydrocarbon chain can be modified to produce detergent. 3. effective in acidic water as H ions is not combine with detergent ions.

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B) FOOD ADDITIVES - Definition of Food Additives Additives – are natural or synthetic substance which are added to food to: i) prevent spoilage ii) ii) impr improv ovee its its appa appaer eran ance ce , tast tastee or text textur uree iii) iii) prev preven entt grow growth th of micr microo oorg rgan anis isms ms iv) iv) prev preven entt oxi oxida dati tion on of fat fatss and and oils oils by oxyg oxygen en in air  air  v) rest restor oree the the colo colour ur of food food dest destro roye yed d dur durin ing g foo food d  processing. - Type Type of Food Additives Additives and Their Functions 1. Preservatives – substance added to food to slow down and prevent the growth of microorganisms in order to kepp the lasts longer. longer. - salts, vinegar and sugar have been used for centuries to preserve food. Preservatives

Molecular  Formula

Uses

Salt sugar 

Drwas water out of the cells of microorganisms Retards the growth of microorganisms.

Vinegar 

Provides acidic condition that inhibits the growth of  microorganisms.

Sodium nitrite  NaNO Sodium nitrate  NaNO

To preserve the meat, sausage, cheese and dried fish. f ish. To prevent food poisoning in canned food. To maintain the natural colour of meat. To make the meat look fresh. To preserve sauces, s auces, fruit juice, jams ja ms and margarine.

Benzoic acid Sodium  benzoate Sulphur  dioxide Sodium sulphate

C H COOH C H COONa SO  Na SO

Used as antioxidants to prevent browning in fuits. Maintain the colour and freshness of vegetables. To prevent thr growth of yeast.

2. AntioxidantsAntioxidants- added to food to i)

peve event oxid oxidaatio tion tha that cause ausess ranc rancid id fats fats and brown foods ii) ii) to slow slow down own the oxida xidattion ion proce rocess ss.. - food containing fats or oils are oxidised and become rancid when exposed to air. This makes the food unpalatable. Th rancid products are volatile organic compounds with 4 odours. 9

( exp : butanoic acid, C H COOH) Antioxidants Butylated Hydroxyanisole (BHA) Butylated Hydroxytoluene (BHT)

Uses To retard rancidity in oils.

Sodium citrate Vitamin C

To stop fats from turning rancid. Inhibits the formation of carcinogeic nitrosamines. Stimulates the immune systems. Protects against chromosome breakage. Preserve the colour of friut juice. Neutralizes free radical compounds before the cell membrane are damaged. Reduce the risk of heart diseases and cancer.

Vitamin E

3. Flavourings - Flavourings are the largest group of food additives. - Function : to improve the taste of food restore taste loss due to processing. - There are 2 types of flavourings : i) Flavour enchancers - Flavor Flavor ench enchanc ancers ers are are chemi chemical calss that that are adde added d to food food to bring bring out the flavours/ to enhance the tastes of food. - Exp Exp : mono monoso sodi dium um glut glutama amate te (MSG (MSG)) MSG is a sodium salt of glutamic acid. It exists as solid fine white crystal. It is added to savoury prepared and processed - frozen foods - spice mixes - canned an and dr dry so soups - salad dressings - meat meat and and fis fish h bas based ed prod produc ucts ts In order to protect the public health, MSG is not allowed in baby foods and less used for the adults. ii)

artificial sw sweeteners  Aspartame • Aspartame is a white , odourless powder, approximately 200 times sweeter than sugar. sugar. • It is used in a variety of foodstuffs.

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It is stable when dry or frozen but breaks down and loses its sweetness over a time when stored in liquids at temperature above 30. • Exp : diet drinks and soft drinks - Synthetic Essences o contain chemicals which are made to resemble natural flavour. Exp :pentyl ethanoate, CH COOC H – give banana flavour and is o cheaper to use. - Many of compounds are used to produce artificial flavours belong to the homologous series of esters. •

4. Stabilizers - a substance which helps to prevent on emulsion ( oil /water droplets suspended in water/oil droplets) from separating out. - It is used in margarine, butter, ice cream and salad cream. - exp : lecithin, mono- and di-glycerides of fatty acids. 5. Thickeners - are chemicals that are added to food to thicken the liquid and to prevent the food from liquefying. - They absorb water and and thicken the liquid in food to produce a jelly-like jelly-like structure. - They are natural carbohydrates. - Exp: Thickeners Explanation Modified st starch Used in in instant so soups an 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. 6. Dyes - chemicals that are added to food to give the colour so as to improve the appearance of food. - is used to add or restore the colour in food in order to • enhance its visual appeal • match consumer expectations 11

give colour to food that have no colour. - artificial food dyes are oftenly used as they are more uniform, less expensive and have brighter colours than natural food dyes. - many food dyes are i) azo compounds ( re red , orange, yellow) - orang orang drin drinks, ks, custar custard d powde powders, rs, swee sweets ts and and apri apricot cot jam. iii) iii) trip triphe heny nyll compo compoun unds ds(( blueblue-br bril illi lian antt blue blue FCF FCF, green green)) - main trend in colour of food towards the use of natural colours is anthocyanin . * found in red grapes, red r ed cabbage sweet potatoes * have antioxidants properties. •

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, (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 Additives

To prevent food spoilage.

Advantages

To improve nutritional value

Medical reasons 12

Life without food additives

Food spoilage always occur 

Malnutrition will occur particularly. Diseases will occur  oftenly

C) MEDICINE - medicine is a substance used to prevent or cure diseases or to reduce pain and suffering due to illness. - it is classified as i) traditional medicine • is a medicine derived from natural resources without being  processed chemically. chemically. • Can be obtained from plants and animals. • Any medicinal plant containing alkaloid is potentially toxic to liver. Some of it interacts with medications resulting in serious side • reactions. • Exp : garlic capsules combined with diabetes medication can cause a sudden decrease in blood sugar 

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ii) Modern Medicine they usually contain a mixture of active ingredientsprepared in different forms such as capsules, pills, solution and suspensions. Exp: Alka-Seltzer Alka-Seltzer (used as antacid) contains sodium bicarbonate (NaHCo ), citric acid and aspirin to neutralises the excess stomach acid. can be classified as follows based on their sffect on the human body : a) analgesics (painkillers) medicines that relieve pain without causing numbness or affecting consciousness. Analgesics Uses Side effect o Reduce fever  Aspirin ♦ Cause brain and liver  o Relieve headaches,  Pain relief and antidamage of illedinflammatory action. children. muscle aches and joint   Acetyl salicylic acid  aches. ♦ Cause bleeding in the (IUPAC name) o Treat arthritis stomach.  Contains 2 functional o Acts as an ♦ Cause allergy groups(carboxylic anticoagulant –  reactions, skin rashes, acid/ester)  prevent clotting blood. asthmatic attacks.  Acidic. o Reduce the risk of  heart attack and strokes.

Paracetamol  neutral

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o

Codeine  Is an organic compounds that contains carbon, hydrogen oxygen and nitrogen elements.  Uesd in headache tablets and cough medicine  Is synthesized from morphine

To relieve mild to moderate pain (headache,muscle and  joint pain, backache ,  period pains) Does not irritate the stomach to bleed.

Causes skin rashes,  blood disorders and acute inflammation of the pancreas. ♦ Cause liver damage. ♦

♦

Cause addiction, depression, nausea, drownsiness

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Is a nacortic drugs. Is a strong analgesics.

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 b) antibiotics Cemicals that destroy / prevent the growth of infected microorganisms. Will not cure the infection caused by viruses such as cold and flu. f lu. Obtained from bacteria/fungi. Broken down by acid in the stomach. Antibiotics Uses Side effects Penicillin o Treat diseases ♦ Cause allergic caused by bacteria  Derived from the reactions such as oneumonia, mould penicillium ♦ Cause daeth for  gonorrhoea, syphilis notatum  people who and tuberculosis. allergiuc at it. o Treat tuberculosis, • Streptomycin ♦ Cause whooping cough nausea,vomitng, • Produced by soil and and some forms dizziness, rashes  bacteris at the genus of pneumonia. and fever. streptomyces ♦ Loss of hearing following long term use. c) psychotherapeutic medicines. A group group of dugs for treating mental / emotional ilness. Psychotherapeutic medicines Stimulants A medicine which activates the level of arousal and alertness of  the the centr central al nerv nervous ous syst system em to reduce fatigue and elevate moon in most people.

Uses i) Adrenaline A need need in dema demand ndin ing g ener energe geti ticc activities. ii) caffeine weak, naturally occuring stimulant found in coffee, tea and cola drinks. iii) Amphetamines Strong synthetic stimulants Increase aler alertn tnes esss & phy physical ical ability. Increase the heart *repiration rates & blood pressure.

Side effects Cause addiction

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Antidepressants Medicine used primarily in the treatment of depression.

Antipsychotic i) chlorpromazine ii) haloperidol iii) clozapine

i) tranquilizers to clam down a person reduce tension & anxiety

cause drowsiness, poor  coordin coordinati ation on and light light headedness, respiratory difficulties, sleeplessness, coma and death if overdose.

i) Barbituarates Cause sleep (high dose) To sedate, calm and relax individual Caus Causee addi addict ctio ion n and and in low doses. habit forming Cause death. To trea treatt psy psychia chiatr trie ie illn illnes esss such such as Cause mild, dry mouth,  schizophrenia (loses touch with reality)  blurred vision, urimary retention, retention, constipati constipation, on, tremor and less rrest as well well as sedati sedation( on(mor moree clmer/sleepy)

! Drug Abuse – taking drugs excessively and without a doctor’s doctor ’s  prescription.the examples of drugs are ectasy and ice. D) 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 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 s alt 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 . 18

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Check for expiry date . Follow your doctor’s instruction for taking medicine . Keep away from children . Do not overdose .

Intensive scientific research must be carried out to produce new substances and this takes takes more time . Scientists Scientists must patient patient and persevere for their  research and development to produce new chemicals in future .

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