Soap and Detergent

a) Give definition of soap and some examples of soap.

Soap is a salt that is formed from the reaction between an alkali and a fatty acid, RCOOH.

* Soap is a sodium salt if the alkali used is sodium hydroxide.* Soap is a potassium salt if the alkali used is potassium hydroxide.

1) General formula of soup is RCOONa or RCOOK .2) Example of soup :

Sodium palmitate , CH 3(CH 2)14COOH−¿Na+¿ ¿¿

Sodium palmitate is a sodium salt of palmitic acid that is derived from palm oil.

Sodium stearate , CH 3(CH 2)1 6COOH−¿Na+¿¿ ¿

Sodium laurate , CH 3(CH 2)10COOH−¿Na+¿¿ ¿

b) Briefly explain the history of soup manufacturing in a flowchart.

2200 B.C.Although it is believed by many that soap's history actually began around 2800 B.C. in

Babylonia (where historians found a barrel containing a soap-like substance) unarguable proof of soaps existence was first provided by a 2200 B.C. Mesopotamian clay tablet with an

actual soap recipe inscribed on it. This ancient soap making technique described mixing potash and oils to form a cleaning agent.

1500 B.C.Egyptian manuscripts describe a matter created by combining animal fats and vegetable oils to create a soap-like substance. The ancient documents go on to explain another type of soap

that is used in the production of wool.

200 A.D.The very first allusion to soap making in literature occurred by a famous Greek physician

named Galen.

600 A.D.Soap making guilds were formed and the modern formula for soap that we use today was

created.

900 A.D.Soap started to be produced commercially and sold for .3 Dinars per bar.

1700-1800 A.D.During the industrial revolution, soap began its production in factories and stopped being

produced in the home kitchen.

CurrentlySoap is being produced in the same way as it was centuries ago after the industrial revolution. As almost all people in this modern age purchase and use commercially manufactured soaps,

the history of soap making is at somewhat of a standstill.

c) Soap can be prepared through saponification. Use a flow chart to show soap preparation process in the laboratory, starting with the raw materials. Include any relevant chemical process.

Saponification process is a hydrolysis process of ester ( oil or fat ) by alkali. Manufacturing of soap can be divided into 2 stage

Stage 1

I. The two parts of the oil or fat molecule are separated by heating the oil with alkaline solution through hydrolysis process.

II. In this process, the ester molecule is broken up into fatty acid and glycerol by water in the presence of alkali which act as catalysts.

Ester + Water fatty acid + glycerolHydrolysis

Alkali act as catalysts

Stage 2

I. Fatty acid that is released in stage 1 reacts with alkali to form sodium salt of fatty acid which is soap

Fatty acid + sodium hydroxide ( alkali ) Sodium salt of fatty acid (soap) + water

Example:

Vegetable oil + sodium hydroxide sodium salt of fatty acid + glycerol

Preparing soap in laboratory

Aim : To prepare soap through the saponification process.

Material : Palm oil , 5 mol dm−3 concentrated sodium hydroxide solution , sodium chloride powder , red litmus paper and distilled water.

Apparatus : 250 c m3beaker , glass rod , tripod stand , wire gauze , Bunsen burner , spatula , 10c m3 and 100 c m3 measuring cylinder , filter funnel , filter paper and test tube

Procedure :

( ester ) ( alkali ) ( soap )

1. Approximately 5c m3 of palm oil is poured into the beaker.2. Approximately 30 c m3 of concentrated sodium hydroxide solution is added into

the same beaker.3. The mixture is then boiled slowly while being stirred with a glass rod for 10

minutes. The mixture is prevented from bubbling.4. 50 c m3of distilled water and two spatulas of sodium chloride are added.5. The mixture is boiled and stirred for s few minutes.6. The mixture in the beaker is left to cool down and the resulting white solid is

filtered.7. The white solid that is produced is washed with a little distilled water and dried

with filter paper.8. The following test are carried out on the white solid :

a) Touched with fingersb) Some of the white solid is shaken together with some water in a test tubec) Tested with red litmus paper

9. The observation are recorded in the table provided.

Observation :

Test on the white solid ObservationTouch with fingers SmoothShake with water Many bubble is producedRed litmus paper Change to blue

Analysis :

The white solid produced is an alkaline soap. Table salt is added to lower the solubility of soap in water so that the soap can

precipitated out. When sodium hydroxide solution is added , the process of saponification occurs to

produce sodium salt fatty acid which is soap.

Conclusion :

Soap can be prepared through the saponification process.

d) Give definition of detergent and some examples of detergent.

Detergent is a salt that is produced from the reaction between an alkali and a sulphonic acid.

A detergent is the sodium salt of sulphonic acid.

Example of detergent:

a) Sodium alkyl sulphate

Synthetic detergent are made from hydrocarbons that are obtained as by-products of the petroleum industry, for example propene gas, C3H 6

Detergent may contain many other substances in addition to the substances that does cleaning and make it more effective which is called addictives.

e) Use a flow chart to summarize the steps in preparation of detergent.Include any relevant chemical equation.

A synthetic detergent, a sodium alkyl sulfate called sodium dodecylsulfate, will be prepared by reacting dodecyl alcohol (dodecanol) with sulfuric acid.

Dodecanol + Sulfuric acid Dodecylsulfate

The resulting dodecylsulfate is converted to the sodium salt by a reaction with sodium hydroxide.

Dodecylsulfate + Sodium Hydroxide Sodium dodecylsulfate

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f) Both soap and detergent so much better than water alone. Use a flow chart and colourful diagram to summarize the cleansing action of soap and detergent.

When added into water, soap molecule will dissociate into sodium or potassium ions and soap ions.

Soap ions can be divided into two part :

tail

Soap molecule can reduce the surface tension of water to allow it to wet a material’s surface better.

Cleansing action of soap

I. The soap molecule dissolves in water and reduces the surface tension of water. Water wets the dirty surface.

II. The hydrophilic region dissolve in water.III. The hydrophobic region dissolve in dirt.IV. The dirt is lifted off the surface of the material upon shaken and

suspended in water.V. The tail region emulsifies and breaks up the grease into small drops.

head

Consists of the anion region Is ionic Called the hydrophilic region Dissolve in water

Consists of the hydrocarbon region

Molecule that has covalent characteristics

Called the hydrophobic region Dissolve in grease or oil (dirt )

VI. When shaken, the water molecules will attract the soap ions and cause the dirt to detach from the surface of the material.

VII. The soap bubbles help to float the dirt emulsion in the water. When rinsed, the dirt will be removed together with water.

The cleansing action of detergent and soap is fundamentally same. When a detergent dissolves in water, its molecule will dissociate to form sodium or

potassium ion and detergent ion ( detergent anion ). The detergent ion such as R-O-SO3

−¿¿ can be represented in a simplified form by structure below.

Cleansing action of detergents

I. Detergent molecule dissociate to form sodium or potassium ions and detergent ions.II. Hydrophilic region dissolve in water. Hydrophobic dissolve in grease and emulsifies

the grease.III. When the water is shaken, the detergent ion will remove the dirt.

g) Compare and contrast the effectiveness of cleansing action of soap and detergent in hard water by using mid map or table.

O-SO3−¿¿

Ionic head Hydrophilic head Dissolve in water

Hydrocarbon tail Hydrophobic head Dissolve in grease(dirt)

Hard water contains a great amount of calcium and magnesium ions. Soap cannot be used in hard water because the magnesium and calcium ions wil

react with soap ions to form a non-soluble precipitate in water that is called a soap film or scum. Soap cannot produce bubble in hard water.

Soap scum is not easily cleaned. It will leave a clear sediment that can be seen on the clothes and cause the clothes to feel hard.

Properties Soap Detergent

Cleaning power Less powerfull More powerfull

Ease of rinsing It is difficult to wash away all soap on clothes. The soap that remains leave and odour and spoils the fabrics

Rinse out well from clothes

pH Slightly alkaline Can be controlled to suit the cleaning task

Molecular structure Determined by the fatty acids found in the oil or fat used to produce soap

Can be modified to suit the cleaning task. For example, a detergent can be made specially for cleaning toilet bowls

Formation of scum Form scum with hard water Does not form scum with hard water

h) Detergent consists of various addictives. What is the purpose of adding detergent addictives ? Construct a mind map to show the addictives in detergents and its functions.

Addictives Example Function Biological enzyme Amylases, proteases,

cellulasesTo remove protein stains such as blood

Whitening agent Sodium perborate To convert stains into colourless substances

Optical whitener Fluorescent dyes To add brightness and whiteness to white fabrics

Builder Sodium tripolyphosphate To enhance the cleaning efficiency of detergent by softening the water

Suspension agent carboxymethylcellulose To prevent the dirt particles removed from redepositing onto cleaned fabrics.

Filler Sodium sulphate, sodium silicate

To add to tha bulk of the detergents and enable it to be poured easily

Foam control agents Silicones To control foaming in detergent

Fragrance - To add fragrance to both detergent and fabrics

a) What are the purposes of using food additives? Present your information in a mind map.

Food Additives