Soap and Detergent

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Soap and detergent 1. Definition of soap and examples of soap  Soaps are sodium or potassium salts of long chain fatty acids that contain 12 to 18 carbon atom per molecule  Sodium palmimate, potassium oleate and potassium stearate are examples of soaps 2. The history of soap manufacturing : in 1816, the French chemist Michael Chevruel (1786-1889) dicovered that animal fats are composed of fatty acid and glycerol. this discovery constributed to the rapid development of the soap and candle indu
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   Soap and detergent  1.   Definition of soap and examples of soap    Soaps are sodium or potassium salts of long chain fatty acids that contain 12 to 18carbon atom per molecule    Sodium palmimate, potassium oleate and potassium stearate are examples of soaps2.   The history of soap manufacturing :3.   Preparation of soap by saponificationin 1816, the French chemist Michael Chevruel (1786-1889) dicovered that animalfats are composed of fatty acid and glycerol. this discovery constributed to therapid development of the soap and candle industry.in 1816, the Belgian chemist Ernest Solvary (1838-1922) discovered the process tomake soda (sodium carbonate) from common salt (sodium chloride) and calciumcarbonate. this process is known as Solvay Process which produces sodiumcarbonate which is used to making glass, soaps and detergents.Apparatus : beaker, measuring cylinder,glass rod, Bunsen burner, filter funnel, filter paper, wiregauze, spatula and tripod stand.Materials : 5 mol dm -3 sodium hydroxide solution, sodium chloride solution , palm oil, olive oil, cornoil and peanut oil.Procedure :A)   preparation of soap1.   using a small (100cm 3 ) measuring cylinder, 10cm 3 of palm oil is measured out into a beaker.2.   Using a large (250cm 3 ) measuring cylinder, 50cm 3 of concentrated (5mol dm -3 ) sodiumhydroxide solution is measured out and poured into the palm oil in the beaker.3.   The mixture is heated until boiling (figure 5.1(a)). The solution is stirred with a glass rodthroughout the experiment4.   The boiling is continued for about 5 minutes until the layer of oil disappears.5.   The Bunsen flame is then turned off and the reaction mixture is left to cool.B)   To separate the soap from the reaction mixture1.   Three to four spatula of sodium chloride is dissolve in about 100cm3 of water2.   The salt solution is then added to the soap solution obtained in section A. The mixture isboiled again for about 5 minutes (figure 5.1(b)).3.   When the mixture is cooled, a white precipitate is formed, which floats on the surface of themixture.4.   The mixture is filtered (figure 5.1(c)) and washed with distilled water to removw excess alkaliand salts.   4.   Definition of detergent and examples of detergent    Detergents are synthetic cleaning agents made from hydrocarbons obtained frompetroleum fractions.    Sodium alkyl sulphate and sodium lauryl sulphate are examples of detergent.5.   Preparation of detergent    The detergent, sodium alkyl sulphate5.   A small amount of the residue on the filter paper is examined by (a) rubbing it on the hand,(b) shaking it with a water in boiling tube. The observations are recorded.6.   The experiment is repeated using olive oil, corn oil and peanut oil.Figure 5.1 preparation of soapResult :Test Observationa)   Rubber on the hand Soapy (slippery) feelb)   Shaken with water A lot of foam is producedDiscussion :1.   The white residue on the filter paper is soap because it has slippery feel and produces foamwhen shaken with water.2.   The soap produced in section A can be orecipitated from the solution by adding sodiumchloride and boiling the solution again. The process is called salting out.3.   The salting out process occurs because sodium chloride reduces the solubility of soap in waterand causes it to be precipitated.4.   The precautionary step in this experiment is to control the flame of the Bunsen burner. This isbecause boiling is mixture of palm oil with sodium hydroxide solution produces a lot of froth.Conclusion : soaps can be prepared from vegetable oil and concentrated sodium hydroxide solutionby saponification. heat heatVegetable oil ConcentratedNaOH(aq) Glass rodSoapsolutionFilter funnelFilter papersoapfiltrate (a)   saponification (b) precipitation of soap (c) filtration       The detergent, sodium lauryl sulphate6.   The cleansing action of soap and detergent    The ionic ‘head’ (negatively -charged) is soluble in water (hydrophilic) but insoluble in oil    The long hudrocarbon ‘tail’ (neural) is insoluble in water (hydrophobic) but soluble in oil step 1 : reaction with concentrated sulphuric acidlong chain alcohol + concentrated sulphuric acid alkylhydrogen sulphate + waterstep 2 : neutralisation with sodium hydroxide solutionalkyl hydrogen sulphate + sodium hydroxide sodium alkylsulphate + water step 1 : preparation of lauryl hydrogen sulphatelauryl alcohol + sulphuric acid lauryl hydrogen sulphate +waterstep 2 : preparation of sodium lauryl sulphatelauryl hydrogen sulphate + sodium hydroxide sodium laurylsulphate + water solution    STEP 1 ACTION OF SOAP ON DIRT When soap or detergent is mixed with water, it lowers the surface tension of water andwets the dirty surfaceThe negatively- charged ‘heads’ of soap or detergent ions dissolve in water (hydrophilic)   The hydrocarbon ‘tails’ of soap or detergent ions dissolve in the layer of grease (hydrophobic)STEP 2 DIRT BEING SURROUNDED BY SOAP/DETERGENT IONS  if the water is agitated slightly, the grease begins to lift off the surface.STEP 3 LIFTING DIRTH FROM CLOTH on further agitation during waashing, the greasy dirth dirt lifted from the surface sincethe density of grease is less than water.STEP 4 EMULSIFYING DIRT IN WATER when the water is shaken, the grease will be emulsified when it breaks into smallerdropletsthese greasy droplets repel one another because they carry the same charge. as a result,the grease is suspended in the solutionwhen the cloth is rinsed with water, the droplets will carried away.
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