definition soap and examples
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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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