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DEFINITION SOAP AND EXAMPLES

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 16 carbon atoms.

HISTORY OF SOAP MANUFACTURING

Babylonians

made soap

around 2800

B.C.

Purifying oils isrecorded on

Hebrew Tablesaround 4000 B.C.

Ash + LimeCaustic potash

Caustic Potash +fats soap

Process of making soap

ashes or sodium

carbonate from common

salt is patented by

Nicholas Leblane

(French).

After 20 years,Ernest

Solvay ( BelgianChemist)

developed Solvayprocess

Sodium carbonateNa CO

is producedcheaply &

used for glassmaking ,

soaps anddetergent.

Michel Chevreul (French)

discovered animal fats are

cmposed of fatty acids and

glycerol ( Causes rapid

development of soap &

candle.)

Later on, vegetables oilis

used to replace animalfats.

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SOAP PREPARATION PROCESS IN THE LABORATORY

.

STEP 1: Palm oil and concentrated sodium hydroxide solution is poured into a

beaker, heated, stirred until it boil [the layer of oil dissaperar] and cooled

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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STEP 3: Mixture is filtered by filter paper.

So

STEP 2: Water and a few spatulas of sodium chloride was added,boiled again and

cooled. Whiteprecipitate is formed and floats on the surface of the mixture.

Sodium chloride reduces the solubility of soap in water, therefore soap is

easily toprecipitate and floats.

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Procedure:

1. 10 cm3 of palm oil is measured with measuring cylinder 10ml and poured into abeaker 250ml.

2. 50 cm3 of concentrated sodium hydroxide solution 5 mol dm-3 measured withmeasuring cylinder 50ml and poured in the beaker.

3. The mixture is heated and stirred with glass rod until its boiling for 5 minutes.Then, the flame is turned off and the mixture is left to cool.

4. 50 cm3 water and a few spatulas of sodium chloride was added to the mixtureand boiled again for 5 minutes. Then, the flame is turned off and the mixture is

left to cool.

[white precipitate is formed and floats].

5. The mixture is filtered with filter paper, and the residue (soap) is washed bydistilled water.

STEP 4: Solid soap is washed with distilled water to remove excess alkali and

salt.

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Example:

Soap Chemical formula

Sodium palmitate CH3(CH2)14COONa

Sodium stearate CH3(CH2)16COONa

Sodium oleat CH3(CH2)CH=CH(CH2)COOK

Potassium soap is usually used for bathing because its more softer and milder

than sodium.

Palm oil + sodium hydroxide sodium palmitate

+ glycerol

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DEFINITION OF DETERGENT AND EXAMPLES

Detergent is sodium salt for sulphonic acid. Sulphonic acid is an organic acid with chain

lengths of 12 to 18 carbon per molecule.

Two common detergent;

Types of detergent

(a) Anionic detergent(b) Cationic detergent(c) Non-ionic detergent

ii. Sodium alkylbenzenesulphonate

i. Sodium alkylsulphate

(R represent hydrocarbon chain that contain 12 to 18

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PREPARATION OF DETERGENT

Sodium alkyl sulphate & Sodium alkylbenzene sulphonate are anionic detergent.

PREPARATION OF SODIUM ALKYL SULPHATE

Step 1: Sulphonation

Step 2: Neutralization

The alkyl sulphonic acid is neutralized by using sodium hydroxide.

Alkyl sulphonic acid

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PREPARATION OF SODIUM ALKYLBENZENE SULPHONATE

Step 1: Alkylation

Step 2: Sulphonation

Alkyl benzene

Step 3: Neutralization

AMBIK KT PNDRIVE..

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THE CLEANSING ACTION OF SOAP AND DETERGENTS

The cleansing action for soaps and detergent results from their ability;

I. to lower the surface tension of water,II.

to emulsify oil or grease / dirt, and

III. to hold them in suspension in water.

This ability is due to the structure of soaps and detergent

Structure of soaps

Soap consists ofsodium/potassium cations and soap anions.

When a sodium/potassium soap is dissolve in water, it will form soap anions and sodium ion, Na+

or

potassium ion, K+

Sodium soap soap anions + sodium cations [Na+]

Potassium soapsoap anions + potassium cations [K+]

What is soap anions?

From the diagram above shows that the structure of soap anions consists of,

i. hydrocarbon chains known as hydrophobic partii. carboxylate/ionic group known as hydrophilic part

Hydrophobic[hydrocarbon chains] Hydrophilic[carboxilate group]

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Structure of detergent

Detergent ofsodium cations and detergent anions.

When a detergent is dissolve in water, it will form detergent anions and sodium ion, Na+.

What is detergent anions?

i) Sodium alkyl sulphate detergent

From the diagram above shows that the structure of alkyl sulphate anions consists of,

i. hydrocarbon/alkyl chains known as hydrophobic part

ii. sulphate/ionic group known as hydrophilic part

i) Sodium alkyl benzene sulphonate detergent

OSO

Na+

Alkyl sulphate ion

Hydrophobic [hydrocarbon/alkyl chains] Hydrophilic[sulphate ions]

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From the diagram above shows that the structure of alkyl benzene sulphonate anions consists of,

i. hydrocarbon/alkyl benzene chains known as hydrophobic partii. sulphonate/ionic group known as hydrophilic part

Remember this;

In water, soap and detergent dissolves to form soap anions and detergent anions. The anions will

carry out the cleansing action, because these anions consists of hydrophobic and hydrophilic part.

Why?

Hydrophobic is water-hating part, is soluble in oil/grease/dirt, but insoluble in water. Hydrophilic is water-loving part, is soluble in water but insoluble in oil/grease/dirt. Both of the properties of anions, makes soap and detergent act as an effective cleansing

agent.

Alkylbenzene sulphonate anios

Hydrophobic[hydrocarbon/alkyl benzene chains] Hydrophilic [sulphonate

ions]

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How soap and detergent carry out the cleansing action?

- The cloth is dipped in a soap or detergent solutions.

- Soap and detergent reduces the surface tension of water.

- This increase the wetting ability of water, therefore the surface of the cloth is wetted thoroughly.

- Hydrophilic part dissolves in water.

- Hydrophobic part dissolves in dirt/grease.

Soa

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- Mechanical agitation during scrubbing helps pull the dirt/grease free, and break the grease into

small part.

- The droplets do not coagulate and redeposit on the surface of the cloth because the repulsion

between the negative charges on their surface.

- The droplets is suspended in the water forming an emulsion.

- Rinsing washes away these droplets and leaves the surface clean.

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THE EFFECTIVENESS OF CLEANSING ACTION OF SOAP AND DETERGENT

Advantages of soap

1. Soap are effective cleaning agent in soft water.- Soft water did not contains Mg

2+

ions and Ca2+

ions.

- Example: rain water, tap water

2. Soap does not polluted the environment.- Soap is biodegradable (can be decomposed by bacteria)

because it was made from substance that found in animal

and plant.

3. Soap will not harmed the aquatic life.- Soap will not change pH value of river and pool because

soap is salt and weak alkali.

Disadvantage of soap

1. Soap is not suitable for use in hard water.

- Hard water contains Mg2+ ions and Ca2+ ions.- Example: Sea water, river water

Why not suitable?

- Mg2+ and Ca2+ ions react with the soap ions to form an insoluble precipitate knownas soap scum.

- Soap scum reduces the amount of soap available for cleaning, thus wasting soap.-

Soap scum does not rinse away easily.- Soap scum can form deposits on clothes causing them to be grey or yellow in colour.

2. Soap did not effective in acidic water.

- Soap ion react with ion H+

to produce carboxylic acid molecule.

Advantage of detergent

1. Detergent is effective in hard and soft water.- Detergent do not form scum with hard water.- Detergent form soluble substances with calcium or magnesium ions.

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2. Detergent effective in acidic water- Detergent ion did not combine with H

+.

3. Detergent is synthetic cleansing agent.- Structure of the hydrocarbon chain can be modified to

produce detergents with specific properties.

Disadvantage of detergent

1. Detergent can cause pollution to environment- Detergents not biodegradable, so that it cannot be

decomposed by bacteria

2. Detergent harmed to aquatic life- Detergent contains phosphate fertilizer will increases the

growth of seaweed and algae in pond or river. Lots of

soluble oxygen in water will be use up by bacteria to

decompose seaweed and algae when the plant died.

The content of oxygen in water decreases, thus can kill

aquatic life.

3. Detergent produce a lot of foam.- Foam can cover the water surface and prevent the

oxygen dissolves into water, thus will kill aquatic life.

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DETERGENT ADDITIVES AND THEIR FUNCTION

The main substance in detergent is sodium alkyl benzene sulphonate and sodium alkyl sulphate.

Example of detergent is shampoo, clothes washing powder and dishes washing liquid.

Various type of additive is also added to detergent to enhance the cleaning efficiency and to meet

the needs of consumers.

additives Function

Whitening agent (sodium

perborate)

React as bleach agent to vanished the colour stain but did not

fade the colour of the clothes.Biological enzymes (amilase,

lipase, protease, selulase)

React to substance that in organic properties like blood, food

and water. Enzymes dissolve and change it to substance that

can dissolve in water.

Fluorescent agent

(Blancophor)Make the clothes more white, shiny and bright.

Buildup agent

(sodium tripoliphosphate)

Soften hard water, expel ion Mg2+

dan Ca2+

. increase the pH

value

Drying agent

(sodium sulphate,

Sodium silicate)

Ensured that the detergent is always in a dry condition.

Stabilizers To prevent the formation of foamPerfumes To make clothes smell fresh and clean.

Antiseptic substance To kill all microorganism that cause disease and smell.

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