Soaps Essay

876 Words4 Pages
Experiment 12 Fat and Oils; Soaps and Detergents Summary of principles Soaps are carboxylate salts with very long hydrocarbon chains. Soap can be made from the base hydrolysis of a fat or an oil. This hydrolysis is called saponification, and the reaction has been known for centuries. Traditionally, soaps were made from animal fat and lye (NaOH). Soaps are less effective in hard water, which is water that contains a significant concentration of Mg2+ and Ca2+ ions. These ions form precipitates with soap molecules, and this precipitate is often seen as a gray line on a bathtub or sink and is often called “soap scum”. Since soap forms a precipitate with these ions, it means that many of the soap molecules are no longer present in the solution. Therefore, soap will form fewer suds in hard water. “Soft water” is water that contains very few or no ions that precipitate with soap. Soap will therefore be much more effective in soft water than in hard water. Detergents are similar to soaps in that they have a charged head group and a long nonpolar tail group, but they are not prepared from natural fats or oils. Detergents are useful because they do not form precipitates with magnesium or calcium ions, which means that they work in both soft and hard water. Shown below is a typical detergent molecule, sodium lauryl sulfate (which you may recognize from ingredient lists of shampoos or other cleaning products): After detergents started being widely used, it was discovered that they were not broken down in sewage treatment plants. Many streams and lakes became contaminated with detergents and large amounts of foam appeared in natural waters. Biodegradable detergents were then developed. Shown below is an example of a biodegradable detergent, sodium. Pre-Lab Question (in book) Equations and Mechanisms Material Test tubes waste bottle

More about Soaps Essay

Open Document