The simplest is to use lard and soda homemade soap method:
To 20 grams of lard, 7 g sodium hydroxide and 50 ml of water on the beaker, with the alcohol burner. Side of the heating, while stirring constantly, to make lard and sodium hydroxide full response. As the reaction is relatively slow, so This relatively long period of reaction time. in the reaction process, should be added the water several times to make up for the loss due to evaporation of water out.
When you see the reaction mixture is no longer floating on the surface layer of molten state of the original oil (ie no effect of lard), the description has been basically lard and sodium hydroxide reaction completely, you can stop heating. And hot to beaker, add 50 ml hot saturated salt solution, stir, you can place the cooling, so that sodium stearate precipitated from the mixture.
Finally, the upper floating in the solution of solid sodium stearate removed, water will be absorbed on the surface of solid solution (which dissolved the glycerol, the role of salt and not End of sodium hydroxide) wash clean, will it dry after molding, to do became a soap.
The key to this experiment do three things:
1. Lard and sodium hydroxide reaction time must be sufficient, do not be impatient, to other mixtures of oil floating on the surface can not see when to stop heating. If the response is not complete, will contain excess oil soap, wax and sodium hydroxide, this would reduce the cleaning ability of soap, and with the larger alkaline.
2. the reaction process, do not forget to fill the water. mixture should be maintained around 50 ml of water.
3. reaction finished After the mixture before the reaction volume should remain similar. stearate sodium precipitation, the mixture still have a certain amount of water to glycerol, sodium chloride and sodium hydroxide have not completed the role of stay in the water, if too little water , and these three substances are mixed into soap, the impact of its quality.