Preparation of Soap-Lab Report PDF

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A lap report on the preparation of
soap ...

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Preparation of Soap Ashley Sargent Submitted: 9/16/2020

Abstract: Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and alcohol. A lone pair of electrons on the OH- is attracted to the partially positively charged C atom in the C=O bond in the ester. The C-OR’ bond breaks generating a carboxylic acid and alcohol. The overall goal of this experiment was to convert a commercially available fat or oil into soap. The soap was prepared by heating the mixture of sodium hydroxide, ethanol and triglyceride (commercial oil) until they became paste-like mixture before cooling the mixture in an ice bath until cooled to room temperature and filtered using vacuum filtration apparatus. The soap was then stored until the next lab for allowance to dry before observance. The weight obtained from the soap was 80.09 grams. The calculated theoretical yield was 4.59 g of soap. The calculated percent yield was 1,744%. The soap has the precipitate of properties if compare with the synthetic detergent that does not form any precipitate. Soap solution has a higher relative cleanliness compared to the detergent, meaning that the soap solution is greater than detergent.

Aim/objectives: The aim of this experiment was to prepare soap and compare the properties of the soap.

Introduction/Background: Human beings almost never really pay attention to the chemistry of how something that they use in their everyday activity works. Soap and detergent are amongst the items that are frequently being used in our daily life activities. Ways that soap and detergent are used in our daily life are through washing our clothes, washing or hands and bathing. Under the chemistry concept, both soaps and detergents have very similar chemical properties that perform the same basic function of cleaning dirt. Although, both items share a major similarity they also produce differences in their production products, in that, detergents are synthetic and man-made, but soaps are made from natural products. Both detergents and soaps are sold with many additives such as perfumes and sudsing agents to make them more attractive to consumers. Both acidic and hard water reduces the cleansing action of soap. Hard water contains dissolved Ca2+, Mg2+ and Fe3+ ions from the minerals that water passes over. In the presence of these metal ions, the Na+ and K+ convert to insoluble Ca2+, Mg2+ and Fe3+ salts. The cleansing action of soap is reduced because soap molecules are removed from the solution. In order to overcome the problems that hard water create for the cleansing action of soap several techniques can be used. One technique is to soften water using a softening agent such as sodium phosphate, sodium carbonate, etc. Surprisingly, the method of soap production has not changed much from the first production times to this era, which is saponification. Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and alcohol. The word soap is known as a generic term for sodium or potassium salts of long-chain organic acids. The RCO2H functional group, where the R is shorthand for methyl or other complex hydrocarbons, is present in organic acids. The R groups in soaps are hydrocarbon chains that generally contain 12 to 18 carbon atoms. Stearic (animal fat),

lauric (vegetable oil) and palmitic (palm oil) are a few sodium fatty acid that are known as soaps. The R groups in the triglyceride may or may not have the same chain length. Thus, different types of soaps may be produced from the saponification of a triglyceride. Soap works by forming micelles in aqueous solution. When the long chain carboxylate anions are mixed into H2O, they aggregate so that the nonpolar alkyl chains for a micelle and the polar carboxylate groups form the outer surface of the micelle. When the soap molecules have formed micelles, they are fully water soluble. However, the inner core is extremely nonpolar, so dirt particles are soluble inside. Once the dirt is dissolved into the micelles, excess H2O rinses away the micelles, taking the dirt with them. Ultimately, the purpose of this experiment is to stimulate a chemical reaction called saponification by converting fat or oil into soap. Inside the lab, the production of soap includes multiple steps to properly carry out the production of soap. The fats or vegetable oils used in the lab are triglycerides. Triglycerides are esters derived from three fatty acids. After the production of soap, it can be compared to detergents using several different tests such as comparing properties and the emulsification occurrences.

Materials: Sodium Hydroxide H2O Ethanol Triglyceride (commercial oil) Sodium Chloride Vacuum filtration apparatus Buchner funnel Beakers Ice bath Heating apparatus Graduated cylinder Materials/Compounds Ethanol

Sodium Hydroxide

Sodium Chloride

Glycerol

Pictograms

Experimental procedure: To start the experiment, we weighed 2.5 g of NaOH and added it into a 50 mL beaker. Then to that same beaker we added 10 mL of H2O and 95% of CH3CH2OH and stirred it until the NaOH dissolved. Next, 5 g of oil was placed into a 250 mL beaker and the basic solution was added. This mixture was then heated in a bath of boiling H2O for 45 minutes and after 20 minutes of heating the mixture, another 20 mL of 50:50 H2O:CH3CH2OH was added. While this mixture was heating, we dissolved 25g of NaCl into 75 mL of H2O in a 400 mL beaker. After the 45 minutes of heating are finished, the hot solution was poured into the NaCl solution. The mixture was then stirred thoroughly and placed in an ice bath to cool until room temperature. The soap was then collected by vacuum filtration and allowed to dry in a Buchner funnel under vacuum for 15 minutes. Lastly, we transferred the soap to a watch glass and so it can be allowed to dry until the next lab period before obtaining its weight and calculating the percent yield.

Results/Data: Weight of Soap: 80.09 g Calculations: a. Actual yield = 80.09

b. Theoretical yield of soap = 4.41 g TG * 1 mol TG/680.595 g TG *3 mol Soap/1 mol TG * 236.175 g Soap/1 mol Soap =4.59 g Soap

c. Percent yield =actual yield/theoretical yield* 100 = 80.09g/4.59g*100 =1,744%

Equation:

Structure of Compounds

Glycerol

Sodium Hydroxide

Triglyceride

Ethanol

Detergent Molecule

Biodegradable Detergent molecule

Discussion/Conclusion: In this lab, our goal was to convert commercially available oil into soap and compare the soap to detergent. We were able to create soap on a small batch scale, as planned. The theoretical yield of soap was 4.59 g. The percent yield of the soap was 1,744%. In the results it was recorded that the mass obtained from the soap was 80.09 grams. The reason that the mass was so large is because there could have been water remaining in the soap even after allowing it some time to dry. This large mass resulted in a high number for the percentage yield. Observing the soap, it could be seen that the soap was not smooth like other laboratory students’ soap. The soap that resulted from the experiment seem to have ridges on it and seems to be rougher upon sight. There could have been many errors whilst performing the lab. The first is not measuring the materials right before pouring them into beakers or heating them. The second may have been heating the solution/mixture too much before removing it. The third is not letting the mixture cool down to room temperature before placing it into the cool bath. A mistake that was probably made but could have been avoided is not letting the NaOH dissolve properly. To prevent this mistake, we should have made sure when mixing the oil with ethanol and sodium hydroxide, the mixture is stirred completely to ensure the solution is dissolved completely.

NaCl helps to precipitate the soap from aqueous solutions. The soap is formed by the precipitation of the ‘common salt or NaCl’. When the NaCl is added in the aqueous solution then the reaction occurs, and the soap precipitates out from the solution. When the soap is added to the solution then the solubility of the soap becomes decreased and the soap precipitates out from the solution as a solid form. Sodium acetate and sodium propionate make poor soaps because they do not have a long enough hydrocarbon portion with which to bond to the dirt. Good soaps are made from those fatty acids which contain long hydrocarbon chains in addition to the ionic “head” portion. If the hydrocarbon portion is not sufficiently long, the acid will be too polar to dissolve dirt.

References:

Syahiirah, Nurlina. “CHE485 - Lab Report on Preparation of Soap and Properties Comparison with Synthetics Detergent (2017).” Academia.edu, www.academia.edu/36294844/CHE485_Lab_Report_on_Preparation_of_Soap_and_Prope rties_Comparison_with_Synthetics_Detergent_2017_....