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Making Soap: Base-Catalyzed Hydrolysis of a Triglyceride

Abstract: 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. Experimental: 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 water. A small amount of the soap was added to the first test tube. The other test tube was a control. The test tubes were sharply tapped in order to mix the contents. The test tube was observed and recorded. 2. ) A soap solution was prepared in a small beaker by adding 25 mL of distilled water and a small amount of the soap.

The contents were gently warmed in a warm water bath in order to dissolve as much of the soap as possible. 3. ) 5 test tubes were prepared and labeled 1-5. 5 mL of the soap solution that was previously prepared, was added to each test tube. 4. ) 2 drops of 5% CaCl2 were added to test tube 1. The test tube was observed and the observations were recorded. 5. ) 2 drops of 5% MgCl2 were added to test tube 2. The test tube was observed and the observations were recorded. 6. ) 2 drops of 5% FeCl3 were added to test tube 3. The test tube was observed and the observations were recorded. 7. ) 2 mL of tap water wad added to test tube 4.

The test tube was observed and the observations were recorded. 8. ) Test tube 5 served as the control because it only contained the soap solution. A drop from test tube 5 was placed onto pH paper in order to test the pH. The pH was recorded. Data: Mass of oil and graduated cylinder 74. 57 g Mass of empty graduated cylinder 66. 43 g Mass of soap product (with filter paper) 18. 72 g Physical properties of soap light yellow, slimy and clumpy, appears like apple sauce Physical properties of soap from another group yellow, soft, porous, and thick Observations of solubility of Mineral oil: Distilled water appears like water

Soapy water cloudy and clumpy. Test tube #1 CaCl2 Semi-cloudy; mostly clear Test tube #2 Mg Cl2 white; real cloudy Test tube #3 FeCl3 yellow/ orange Test tube #4 Tap water clear; bubbled slightly Test tube #5 pH of soap solution pH = 8 Analysis: –Calculations 1. ) Mass of oil = (Mass of graduated cylinder & oil) – (mass of empty graduated cylinder) (74. 57g) –(66. 43g) = 8. 14 g 2. ) Mass of soap produced = (Mass of soap) – (mass of filter paper) (18. 72g) – (0. 02g) = 18. 7 g 3. ) Mass of fatty acids = (Mass of soap)(0. 90) (18. 7g)(0. 90) =16. 83 g 4. ) Percent oil that is fatty acid (Mass of oil )/ (mass of fatty acids) X 100 8. 14 g) /(16. 83 g) X 100 =48. 4 % Our corn oil soap was similar to a group that prepared walnut oil soap. They were similar in appearance because they were both yellow and thick. The primary fatty acid in the corn oil soap was linoleic acid. The soap in the experiment is an emulsifier because the insoluble material (corn oil) became soluble when mixed with mineral oil and water. This was evident because the soap appeared yellow and cloudy in the test tube that contained soap, mineral oil, and water. When CaCl2 and MgCl2 are added to the soap solution, the solution appears white and mostly cloudy.

Calcium and magnesium are salts that are added to hard water, they have lost their ability to emulsify and therefore are insoluble and cloudy. FeCl2 is added to acidic water and is converted to fatty acids which are insoluble, which is the test tube appears yellow/orange in color. The tap water in the lab is hard because when magnesium and calcium are added to the water appear insoluble because they are unable to emulsify. This reaction is only apparent when added to hard tap water, which is why the water in the lab is hard. Results and Conclusions: 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. In the experiment can conclude that the vegetable oil had a primary fatty acid called linoleic acid, which was evident during the saponification reaction. While under basic conditions the negative carboxylic acid and positive ions produce a Carboxylate salt of the fatty acid.

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 the experiment, the simple soap did appear to be a good emulsifier because the soap did dissolve in the mixture of mineral oil and water. The insoluble material (corn oil) became soluble when mixed with mineral oil and water. This was evident because the soap appeared yellow and cloudy in the test tube that contained soap, mineral oil, and 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. In the experiment, when hard water was added to the calcium and magnesium, the salts 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. The purpose of this experiment was completed properly.

The experiment demonstrated saponification in order to prepare a simple soap made from a vegetable oil. The emulsifying properties were also tested in order to demonstrate the reactions that occurred in hard and acidic water. The physical properties of the vegetable oil were also compared to the different physical properties produced from a different vegetable oil. Possible errors include that the experiment was initially done with sodium chloride instead of sodium hydroxide. In which case the experiment was immediately restarted and done properly the second time. No other possible errors were evident.

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