jim
Chemical reactions are the heart of chemistry. People have always known that they exist. The Ancient Greeks were the firsts to speculate on the composition of matter. They thought that it was possible that individual particles made up matter. Later, in the Seventeenth Century, a German chemist named Georg Ernst Stahl was the first to postulate on chemical reaction, specifically, combustion. He said that a substance called phlogiston escaped into the air from all substances during combustion. He explained that a burning candle would go out if a candle snuffer was put over it because the air inside the snuffer became saturated with phlogiston. According to his ideas, wood is made up of phlogiston and ash, because only ash is left after combustion. His ideas soon came upon some contradiction. When metal is burned, its ash has a greater mass than the original substance. Stahl tried to cover himself by saying that phlogiston will take away from a substance's mass or that i!t had a negative mass, which contradicted his original theories. In the Eighteenth Century Antoine-Laurent Lavoisier, in France, discovered an important detail in the understanding of the chemical reaction combustion, oxigine (
"Chemical Reactions," Encyclopedia Brittanica MACROPEDIA, 1995, Vol. 15 ion rate. This is also a way to control reactions. A good example in nature of a catalyst is in a firefly. The reaction that releases the light is complex. Lucifern, which the firefly makes naturally, is oxidized in the presence of luciferase, another natural enzyme, which acts as a catalyst in the reaction. Thus, the reaction makes an excited form of luciferase, which soon returns to its original state. Energy as light is released when the lucifrase returns to its normal state. The insect can easily control this reaction with an inhibitor it naturally makes. Another contributor in this consideration is entropy. It is the measure of energy not available for work in the reaction that becomes energy moved to disorder. Entropy is simply a measurement of unusable energy in a closed thermodynamic system. An acid and base reaction is another thing to consider. Acids and bases react very readily to each other. When an acid and a base react, they form water and a salt. Acids and bases! oxygen). He said that combustion was a chemical reaction involving oxygen and another combustible substance, such as wood. John Dalton, in the early Nineteenth Century, discovered the atom. It gave way to the idea that a chemical reaction was actually the rearrangement of groups of atoms called molecules. Dalton also said that the appearance and disappearance of properties meant that the atomic composition dictated the appearance of different properties. He also came up with idea that a molecule of one substance is exactly the same as any other molecule of the same substance. Pauling, Linus and Peter, Chemistry, W. H. Freeman and Co., 1975 "Dances With molecules," Science News, Vol. 147, May 27, 1995 nH2OC(C6H4)CO2H + nHOCH2CH2OH -* [...OC(C6H4)CO2CH2CH2O...]n 2nH2O in which n is a large number of moles. A chain reaction is a series of smaller reactions in which the previous reaction forms a reagent for the next reaction. The synthesis of hydrogen bromide is a good example: H2 + Br2 -* 2HBr Exoergic, or exothermic, reactions release energy during the reaction. Combustion is one of the major reactions that do this. The burning of wood, or any other fuel, gives off heat, and the burning of glucose in our bodies gives off both energy and heat. Endoergic, or endothermic, reactions absorb energy during the reaction. The melting of an ice cube is an example of an endothermic reaction.
Some common words found in the essay are:
Amedeo Avogadro, Kinetics Kinetics, California Berkly, Ernst Stahl, Robert Merrifeild, University Illinois, Nineteenth Century, Joseph-Lois Gay-Lussac, chemical reactions, Lavoisier France, , chemical reaction, reaction reaction, reaction reactants, reaction rate, reaction called, acids bases, reactions chemical, acids bases react, reactions chemistry, types reactions, reaction oxidation goes, chemical reactions chemistry,
Approximate Word count = 1969
Approximate Pages = 8 (250 words per page double spaced)
|
