Showing posts with label boiling. Show all posts
Showing posts with label boiling. Show all posts

Friday, February 19, 2010

Saponification

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a process in which ESTERS are hydrolysed by the action of acids, alkalis, boiling with water or superheated steam. If alkalis are used then SOAPS are produced and this is the origin of the term (sapo is the Latin for soap).

Taken from Dictionary of Science

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Saponification is the hydrolysis of an ester under basic conditions to form an alcohol and the salt of a carboxylic acid (carboxylates). Saponification is commonly used to refer to the reaction of a metallic alkali (base) with a fat or oil to form soap. Saponifiable substances are those that can be converted into soap.


Sodium hydroxide (NaOH) is a caustic base. If NaOH is used a hard soap is formed, whereas when potassium hydroxide (KOH) is used, a soft soap is formed. Vegetable oils and animal fats are fatty esters in the form of triglycerides. The alkali breaks the ester bond and releases the fatty acid salt and glycerol. If necessary, soaps may be precipitated by salting it out with saturated sodium chloride. The saponification value is the amount of base required to saponify a fat sample.


In a classic laboratory procedure the triglyceride trimyristin is obtained by extracting nutmeg with diethyl ether. Saponification to the sodium salt of myristic acid takes place with NaOH in water. The acid itself can be obtained by adding dilute hydrochloric acid.

Taken from Wikipedia



Monday, January 11, 2010

Vacuum Distillation


distillation performed under reduced pressure. Since a reduction in pressure also reduces the boiling point of substances it means that certain substances which at normal pressures would decompose (break down), can be distilled.

Taken from Dictionary of Science

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Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure (usually less than atmospheric pressure) causing evaporation of the most volatile liquid(s) (those with the lowest boiling points). This distillation method works on the principle that boiling occurs when the vapor pressure of a liquid exceeds the ambient pressure. Vacuum distillation is used with or without heating the solution.

Taken from Wikipedia