Sunday, May 17, 2009
COSMETICS
REFRIGERATOR
According to Mary Bellis, refrigeration is the procedure of getting rid of heat from an enclosed space, or from a substance, to bring down its temperature. A refrigerator uses the evaporation of a liquid to absorb heat. The liquid, or refrigerant, used in a refrigerator evaporates at an extremely low temperature, creating freezing temperatures inside the refrigerator. It's all based on the following physics: - a liquid is rapidly vaporized (through compression) - the quickly expanding vapor requires kinetic energy and draws the energy needed from the immediate area - which loses energy and becomes cooler. Cooling caused by the rapid expansion of gases is the primary means of refrigeration today.
It was recently discovered that a part of the oxone layer around the earth which contains Chlorofluoro Carbon (CFC) is used in refrigerators to keep food cold. The refrigerator takes in heat at low temperature and rejects it at a higher temperature( second law of thermodynamics) energy is conserved during the process, using external energy to drive the process, the refrigerator is a heat pump.
CLEANING AGENT
Soap is a mixture of chemical compounds resulting from the reaction between fats and alkalis. Soap can be introduced by incorporating melting fats into excess sodium hydroxide solution and boil the mixture.
-The pasty boiling mixture is treated with brine.
-This causes a seperation of the content into two layers of which the upper layer contains impure soap.
-It is then washed to remove the excess alkali and salt and treated in various ways.
Detergents are synthetic cleaning products. They are made from petrochemicals. Detergents are used to wash dishes, laudrys, walls and floors. Soaps and Detergent reduces the surface tension of water they help lift dirt from greasy surface thereby reducing the spread of germs.
Sunday, May 10, 2009
FERTILIZERS
Fertilizers contain nitrogen,phosphorus and potassium (N.P.K). Nitrogen is supplied in form of ammonia(NH3) which is obtained from fossil fuels. The ammonium compound used are ammonium trioxonitrate(v) and ammonium tetraoxophosphate(vi). Sodium trioxonitrate is also a source of nitrogen. Ammonium tetraoxosulphate(vi) is sometimes retrieved as a by product from the conversion of coal into coke.
Phosphorus is naturally obtained as rock phosphate. It is treated with hydrogentetra-oxosulsphate(vi) acid so as to make it into a suitable form that can be used to prepare fertilizer the phosphorus is transformed into acids which is converted to ammonium tetraoxophosphate(v).
Potassium in form of salt is mined from underground deposit.
These three elements are mixed together in their right N.P.K proportions. A few other elements like zinc, boron, copper and molybdenum are added depending on their needs in certain region to form a suitable fertilizer to grow plants.
Coagulation is a process when the untreated is passed through large settling tanks where chemicals like potash alum(KAl(SO4)2 or sodium aluminate(III)(NaAlO2) are added to cause flocculation.
Sedimentation.
Sedimentation then occurs where all the impurities clump together to form big particles of dirt or flocs which settles down rapidly.
Filtration.
Filtration -the water is then passed through a filter bed to remove the remaing fine particles of dirt.
Disinfection.
Disinfection is a process when the water is treated with chemicals like chlorine to kill germs other usefull chemicals like iodine and fluorine maybe added in correct amounts as food supplement to prevent goitre and tooth decay.
WATER PURIFICATION
With two thirds of the earth's surface covered by water and the human body consisting of 75 percent of it, it is evidently clear that water is one of the prime elements responsible for life on earth. Further in the body, it regulates the activities of fluids, tissues, cells, lymph, blood and glandular secretions.
Our water must be clean befor it can be used so as to ensure safety, and to avoid unnecessary sickness. That is why chemistry helps us with a way of purifying our water. Water is made of two molecules of hydrogen and one molecule of oxygen(H2O). Rainwater is one of the purest form of natural water because it is formed as a result the condensation of water vapour in the atmosphere, all the types of natural water are in constant circulation forming a gigantic water circle. Water from rainfall, rivers or lakes is stored in reservoirs, this water is purified by various methods like;
- Coagulation
- Sedimentation
- Filtration
- Disinfection.