When most people think of solar electricity an image of big black panels comes to mind. But what exactly happens in or on those panels that can create enough electricity to power a cell phone or a car? The process involves many tiny particles/energies called photons knocking electrons free from a solid piece of material called a semiconductor. These electrons are then free to travel and power things such as cell phones and cars.
The scientific term used to describe this process is the photovoltaic effect. More specifically the incoming photons excite the electrons of the semiconductor into a higher, empty orbital. Because semiconductors allow for the transmissions of electricity much like metals do, electrons can flow creating an electrical current.
One of the most common semiconductors is silicon. It is popular because it can absorb light beyond visible light, mainly infrared light. Even with these abilities it can still only capture about 28% of the energy that reaches it. For this reason solar panels must be linked together to form a strong enough electrical current.
The sun is the most important source of energy for our planet and it would be a shame to waste the energy that is around us every day. I think that although solar energy may be expensive it is a worthwhile investment for the planet’s future.
Source:
Baird, Colin. “Solar cells produce electricity.” Chemistry in Your Life. W.H. Freeman & Company, New York. 2006. 332
Fatty Soap
ReplyDeleteSoap has been used by people from as far back as the Middle Ages. In Roman times, it was produced and used as a cleaning product much as we use it in modern times. Historically, the fatty acids in soap were derived from animal fat which contains glycerol in the form of a triestar with three fatty acids. When heated, the fatty acids can be released turning the substance back into glycerol. With modern technology, manufacturers can use high pressure and temperature water to split the fat into fatty acids and glycerol. Additionally, the fat can decompose by adding a basic substance of sodium and potassium carbonate paired with heating it. This substance can be obtained through a mixture of water and wood ashes, which change the fatty acid into a sodium or potassium, salt.
After this process, salt is added and the soap and glycerol can be removed from the rest of the solution and the glycerol sinks to the bottom of the new mixture. Glycerol then, becomes a by-product of the mixture. This process is referred to as saponification and is very similar to the process of making soap today though the majority of glycerol in removed before soap is sold today because it can be corrosive to the skin. Soft soaps, similar to the ones many have in their bathrooms are known as semisolids and can be found in shaving cream, hand soap and gel soap and are constructed in large by potassium salts. Hard soaps are denser than the water the are generally used in, a process which happens when blowing air into the soap before it cools and hardens. Soap today differs from the soap people have used in the past mainly because of the additives used for color, smell and harshness.
When calcium and magnesium ions dissolve in water they form scum, which is insoluble and prevents the soap from doing its main job: cleaning. Not only that, but it often prevents items from being cleaned. Hard water, which contains a greater amount of calcium and magnesium ions often turns soap to scum at a more rapid rate than soft water which contains less of the ions. Many people prefer soft water when showering because of this and historically people have captured rainwater for use in bathing because it is soft water.
In buying a three-dollar bottle of soap at Target, we rarely consider these elements of the process, though it can be important in analyzing why one’s skin is dry or oily. In looking at the process, it may be beneficial to consumers to understand the system that develops soap to make a better choice!
Baird, Colin. “Soap is manufactured from fats.” Chemistry in Your Life. W.H. Freeman & Company, New York. 2006. 505-506.