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Unformatted text preview: 34 EXPERIMENT 4 Preparation of Soap Objective: Synthesize soap. Compare the properties of soap and a commercial detergent. Introduction: Soap has been made and used by people for ages, although the purposes to which it was put are not known. Inscriptions on excavated clay cylinders indicate that the Babylonians had devised a method for making soap as early as 2800 BC. The Egyptians were making as early as 1500 BC. Biblical evidence suggests that the Israelites were also making soap. Whatever its original purposes, the use of soap for personal hygiene had definitely occurred by the second century AD. The Alexandrian physician Galen (130 200 AD) mentions its use for washing the body. Soap was known during Roman times, but was seemingly unpopular as a personal hygienic. The Romans preferred to use perfumed oils, which they scraped off the skin with a specialized piece of metal. The soap making process known to the Romans was the same process as was used by previous civilizations: the boiling of animal fats and vegetable oils with ashes. Presumably, the unpleasant appearance and aroma of these early soaps accounted for their unpopularity. Little is known about the use of soap during the Dark Ages. Like so many things during the Dark Ages, knowledge of its value was probably lost and its use declined. The manufacture of soap in Europe and the Mediterranean region had reemerged by the end of the first millennium. Soapmakers guilds guarded their trade secrets closely, although the basic process was unchanged from earlier times, except for the addition of fragrance. A major step toward large-scale commercial soapmaking occurred in 1791 when the French chemist Nicholas Leblanc patented a process for making soda ash (sodium carbonate) from common salt. Soda ash is the alkali in ashes that reacts with fats and oils to form soap. The large quantities of good quality, inexpensive soda ash available because of the Leblanc process allowed soap to be made on a larger scale and at a more affordable cost. Soapmaking was put on a more scientific footing about 20 years later when the French chemist Michel Eugene Chevreul discovered the chemical nature of and relationship between fats, glycerine, and fatty acids. The combination of these scientific discoveries with the increasing industrialization of society made soap broadly available, changing it from a luxury item to a necessity. The manufacture of soap remained essentially unchanged from Leblancs time until 1916, when the first synthetic detergent was developed in Germany in response to a World War I- related shortage of fats. Detergents are made from petroleum-derived hydrocarbons. The greater availability and number of ways petroleum-derived hydrocarbons can be chemically combined to make detergents further increased the production and availability of detergents, so that today detergents are produced and used in much greater numbers than is soap. However, soap is still used in considerable amounts for personal hygiene and other applications. used in considerable amounts for personal hygiene and other applications....
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- Fall '07