Friday, 6 October 2017
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.
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.
FUN IN THE KITCHEN!!
Thursday, 21 September 2017
Friday, 23 June 2017
HOW TO DETECT LIPIDS IN FOODS USING ALCOHOLWhat are lipids?
Lipids are organic biomolecules formed mainly of carbon, hydrogen and oxygen. They accumulate large amounts of energy and perform many functions in living things. They make up biological cell membranes, protect some organs, regulate body functions, in the case of sex hormones and vitamins A,D,K,E. They are excellent thermal insulators. Some are essences and others are plant pigments.
Lipids are insoluble in water but soluble in organic solvents such as alcohol. This property was used in this experiment.
María put samples of food in different beakers and added alcohol. She let the mixture stand for a few minutes.
When this is done, a clear liquid should float on top. If the liquid is white it is that too little food or alcohol has been used.
After a while she took some of this clear liquid and with the use of a pipette and put it into a test tube. Now she added a few drops of water and observed. In some test tubes the liquid remained clear and in others it became cloudy. The cloudy samples indicate the presence of lipids. The samples that remained clear indicate that the sample does not have lipids or at least not significant amounts.
Alcohol dissolves lipids present in food samples. When water is added the liquid becomes cloudy. It is because a lipid emulsion, in which water and alcohol act as an emulsifier agent, are formed. The emulsifier causes the lipids to remain suspended in the water in the form of drops. Due to the suspension the mixture takes on a cloudy whitish appearance indicating the presence of lipids in the sample.
HOW TO DETECT STARCH IN FOOD USING IODINE.
Iodine changes colour when in contact with starch. Using a pipette María added a few drops of iodine to different food samples. The foods that contain starch, such as bread, pasta or rice, turned black or dark blue.
Starch comes from plants, it is a carbohydrate and is therefore made up of carbon, hydrogen and oxygen. It consists of a large number of glucose molecules joined together. This polysaccharide is produced by most green plants. It is the most common carbohydrate in human diets and is contained in large amounts in foods like potatoes, wheat, rice etc.