Soap and Detergent

CONTENTSmeaning of soapsoap preparation processmeaning of detergentdetergent preparation processcleansing action of soap and detergentcompare and contrast the effectiveness of the cleansing action of soap and detergentadditives in detergent and their respective functions

MEANING OF SOAPGeneral formula:RCOONa+orRCOO K+

Example:Sodium palmitate, CH3(CH2)14COO-K+Potassium stearate, CH3(CH2)16COO-K+

SOAP PREPARATION PROCESSSoaps are prepared by the alkaline hydrolysis of fats and oils. This process is known as saponification.

A by-product of this reaction is glycerol which is useful as in foods, as an antifreeze, as a tobacco-moistening agent, and in the manufacture of nitroglycerine and dynamite.Oil or fatAlkaliGlycerolSoaps Saponification is the alkaline hydrolysis of ester using alkali solutions

Example:

MEANING OF DETERGENTR OSO3- alkylbenzene sulphonate ion alkyl sulphate ion

DETERGENT PREPARATION PROCESSPreparation of sodium alkyl sulphate:Step 1: Reaction with concentrated sulphuric acid

Step 2: Neutralisation with sodium hydroxide solution.

Preparation of sodium alkylbenzene sulphonateStep 1 : Alkylation

Step 2 : Sulphonation

Step 3 : Neutralisation

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

CLEANSING ACTION OF SOAP AND DETERGENTA piece of cloth with a greasy stain on it, is dipped in a soap or detergent solution. Soap or detergent reduces the surface tension of water. This increases the wetting ability of water. Therefore, the surface of the cloth is wetted thoroughly.The hydrophobic part of the soap or detergent anion dissolves in the grease. The hydrophilic part is attracted to the water molecules.Mechanical agitation during scrubing helps pull the grease free and also break the grease into small droplets.The droplets do not coagulate and redeposit on the surface of the cloth due to the repulsion between the negative charges on their surface. These droplets are suspended in water forming an emulsion. Rinsing washes away these droplets and leaves the surface clean.hsleonhs@hotmail.com

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EFFECTIVENESS OF THE CLEANSING ACTION OF SOAP AND DETERGENT

CharacteristicSoapDetergentCleansing abilityWeakerStrongerRinsing abilitydifficult to rinse completely. Soap that is left behind damages the material Rinses easily and completely out of clothes and other objects.Molecular structureIt can only be determined by the structure of the fatty acid used to produce soapIt can be modified to suit the job of cleaning. For example, the formula of a detergent can be specially made to be able to clean dishes and other utensils onlypHAlkalineCan be controlled to suit the type of detergent requiredSuspensionForms scum in hard waterDoes not form scum or any other kinds of suspension in hard water

ADDITIVES USED IN DETERGENT AND THEIR RESPECTIVE FUNCTIONS

AdditivesFunctionBiological enzymes (amylase, lipase, protease)Break down fat and protein molecules in food stains to produce fatty acids, glycerol and amino acids that are soluble in water, thus increase the cleansing power of a detergentWhitening agents (sodium perborate)Remove stains, clothes become white and cleanerBuilders (sodium tripolyphosphate)Soften hard water by removing calcium ions, Ca2+ and magnesium ions, Mg2+, increase the pH value of waterBrightenersMake fabrics appear white and brighterDrying agents (sodium sulphate, sodium silicate)Ensure that the detergent in powdered form is always in a dry conditionStabilisersPrevent the formation of foamPerfumesMake clothes smell fresh and clean

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