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Soap can be made from many oils and fats. The reaction is a double displacement involving a
strong base such as sodium hydroxide and fats. (a) Obtain animal fat from a butcher. Boil
this fat in water and the oil will separate on the surface. When cold, the fat will solidify and
it can be separated from the water. Melt the fat again and strain through several layers of
cloth. (b) Weigh this fat and then weigh out about one third as much sodium hydroxide
pellets. Take care not to touch either the solid sodium hydroxide or the solution, because it
is very caustic. Heat the fat in an iron saucepan or dish and, when it is molten, slowly add
the sodium hydroxide solution with continuous stirring. Heat with a small flame to avoid
boiling over. Allow the fat and the sodium hydroxide to boil for 30 minutes. Stir the
mixture frequently. (c) The next stage is to weigh out common salt, sodium chloride; about
twice the weight of sodium hydroxide used in (b) is needed. After the 30 minutes boiling,
stir this salt well into the mixture. Then allow to cool. The soap separates as a layer at the
top. Separate this soap from the liquid below, melt and pour into matchboxes where it will
solidify again as small bars of soap.
sharon kalunda answered the question on April 12, 2019 at 08:50
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