Saturday, December 26, 2009

After you make soap, first you dissolved vegetable oil in ethanol. what happens to ethanol during the reaction

I measure 23ml of vegetable oil into a 250-ml flask. add 20ml of ethyl alcohol,20ml of sodium hydroxide and stir under heat for 20 minute. then put it in a flask with ice cold H2O to cool it. then add150 ml of saturated sodium chloride to the soap mixture while stirring.and vacuum the top of the H2O off the top.After you make soap, first you dissolved vegetable oil in ethanol. what happens to ethanol during the reaction
The ethanol is put inside just to increase the overall fat - water NaOH surface. (because the ethanol dissolves both of them). The hydrolysis of the fat happens only on this surface, so it makes the reaction proceed faster. Only change that could happen is esterification of fatty acids, that are created, but the environment is too alkaline for this to happen (FA salts are unreactive.) So no chemical change happens. Also the soap is less soluble in the ethanol than in the water so it help to salt-out the soap.After you make soap, first you dissolved vegetable oil in ethanol. what happens to ethanol during the reaction
doesnt it get changed to glycerol?

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