Making Soap: Base-Catalyzed Hydrolysis of a Triglyceride

Topics: Water, Fatty acid, Ester Pages: 6 (1694 words) Published: November 23, 2011
The main reason for this experiment is to prepare a simple soap made from vegetable oil. The physical properties will be tested in order to demonstrate the reactions that occur. The experiment can conclude that the vegetable oil had a primary fatty acid called linoleic acid, which was evident during the saponification reaction. The simple soap did appear to be a good emulsifier because the soap did dissolve in the mixture of mineral oil and water. In hard water the calcium and magnesium did loose their effectiveness and became insoluble in the solution. When magnesium was added to acidic water, the salt was converted to a fatty acid, and was also insoluble. Background:

The purpose of this experiment is to demonstrate saponification in order to prepare a simple soap made from a vegetable oil. The emulsifying properties will also be tested in order to demonstrate the reactions that occur in hard and acidic water. The physical properties of the vegetable oil will be compared to a different physical properties produces from a different vegetable oil. Triglycerides are fats found in oils. Triglycerides have three components; glycerol, alcohol functional group, and fatty acid. Triglycerides can vary in size and structure depending on the fatty acid attached. Glycerol is theoretically three ester bonds. In the experiment the ester bonds are broken down through a process called saponification. The product of this reaction is soap. An alcohol and carboxylic acid are also produced when an ester bond is broken. While under basic conditions the negative carboxylic acid and positive ions produce a Carboxylate salt of the fatty acid. Therefore a soap produced can create many different Carboxylate salts. Carboxylate salts have a water-soluble portion and a portion that is hydrophobic. As a result of having a water-soluble and a fat-soluble portion allows the soap to act as an emulsifier. This allows materials that are not normally soluble to become soluble in water. In hard water, Carboxylate salts of fatty acids loose their effectiveness as emulsifiers because the salt is insoluble in water and will become removed from the solution. Conflictingly, when Carboxylate salt is added to acidic water, the salt is converted to a fatty acid, which are insoluble.

Preparation of Soap
1.) The specified graduated cylinder was used to measure 12 mL of oil. The graduated cylinder and the oil, were weighed and the mass was recorded. The oil was transferred into a 125 mL Erlenmeyer flask. The empty graduated cylinder was reweighed. 40 mL of 95% ethanol and 10 mL of 25% NaOH were added to the Erlenmeyer flask. 2.) The flask was placed into a hot water bath. The flask was held in the bath using a straight clamp attached to a ring stand. The mixture was stirred constantly and was heated. If the contents in the flask began to boil vigorously, the flask was removed from the boiling water until the bubbling was settled. The contents were heated for 45 minutes. 3.) The mixture was cooled in an ice water bath. 50 mL of saturated sodium chloride was added to precipitate the soap. The contents were stirred using a glass stirring rod. 4.) A piece of filter paper was weighed and placed into the funnel before the soap was filtered. After the soap had been filtered, two 10 mL portions of ice water were poured over the soap in order to clean it. The soap was sucked for about 10 minutes in order for it to dry. 5.) The appearance of the soap was observed and recorded. The soap was scraped into a weighing dish and weighed. The weight of the soap was recorded, including the filter paper. 6.) The physical properties of two different soaps were compared. The similarities and differences were recorded. The soap was discarded into the appropriate waste container. Properties of Soap

1.) The emulsifying properties of the soap were tested in 2 test tubes by adding 10 drops of mineral oil and 5 mL of distilled...
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