Friday, 29 September 2017


 Our students have collected the used oil from the school's kitchen to make hand made soap.  The disposal of this used oil is often a difficult task, just pouring it down the drain may seem like a simple solution but it can have terrible and expensive consequences for the environment. Fat in drains can lead to blocked pipes, sewer blockages in municipal lines and if it ends up in nature, in rivers, lakes or the sea it has a very negative impact on the environment.
 One of the solutions is to turn these fats into other things. There are many countries that offer recycling programs for safe cooking oil disposal to later change the oil into biodiesel, candles, dog treats and soaps.
Our students worked very hard to bring the used school's kitchen oil to the laboratory and distribute it into smaller containers to make it easier to handle during the soap making process. In the following pictures you can see the soap making process. These students spent many hours making soap, often during their morning and lunch breaks. The project was presented at the school's Science Fair where the soaps were sold. The money collected  was handed to the school's charity project.

 Saponification is the process by which triglycerides react with sodium or potassium hydroxide (lye) and produce glicerol and a fatty acid salt , called soap. The triglycerides are most often animal fats or vegetable oils. When sodium hydroxide is used, a hard soap is produced. Using potassium hydroxide results in a soft soap.
 The chemical reaction between any fat and sodium hydroxide is a saponification reaction.
triglyceride + sodium hydroxide (or potassium hydroxide) → glycerol + 3 soap molecules

1. When the caustic soda is mixed with the oil, the fatty acid molecules are broken.
2. Half of the molecules are mixed with hydroxide, producing glycerin (alcohol). This evaporates later.
3. The other part join with the sodium. With this soap is produced.

 The students designed a logo for their soaps and used different decorative elements, most of them recycled materials, to pack and prepare them for sale at the Science Fair.


The environmental problem of cooking oil

Thursday, 21 September 2017


Print these worksheets as soon as posible and bring them to the class.