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The Story on Potential Energy
Potential energy is energy stored within a body due to its position. For example, a bowling ball held up in the hand of a person contains stored energy. Gravity tends to bring the ball back to ground surface. If the bowling ball is dropped, it will fall down to the ground and the potential energy in the ball will be converted to kinetic energy. Due to the law of conservation of energy, it can never be created or destroyed, only transformed. This is why all forms of energy simply change from one form to another.
There are various forms of potential energy such as gravitational, elastic, nuclear, electric and chemical potential. Here we will focus on the latter.
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Bonding with Chemical Potential Energy
Chemical potential energy is that which is stored within the bonds of atoms and molecules of a substance. The bonds have stored chemical potential energy which is released when they are broken and the substance undergoes a chemical reaction. In such processes, conservation of mass is maintained. Bonds are broken and reformed but the amount of matter remains unchanged. An example of this principle is in a combustion reaction within a car's engine. The gasoline reacts with oxygen when ignited by a spark in the engine. Chemical potential energy that once was stored is then released and the car is set in motion. However, conservation of mass still occurs as the mass of the gasoline and oxygen equal the products, which are the mass of carbon dioxide and other emissions. Some other examples of this type of energy include the burning of fossil fuels such as coal, metabolic breakdown of food in organisms through digestion, conversion of solar energy into chemical energy by plants through photosynthesis, and conversion of electrical energy through electrochemical reactions. In all of these reactions, the energy comes from a re-arrangement of electrons in the orbital shells. The nucleus of an atom is not involved in any of these reactions.
Chemical potential energy is dependent on three main factors:
1. Mass of the object
2. Nature of the chemical-specific heat
An object's mass determines how much energy will be converted and is a good estimation of the chemical potential. The temperature can influence the change in an object's chemical energy; at higher temperatures more bonds will be broken and the substance can undergo a complete chemical reaction. The reactions can be either endothermic or exothermic. In endothermic reactions, more heat is absorbed to break the bonds while in exothermic reactions more heat is released. Chemical potential energy depends on the strength of the bonds; strong bonds have low energy and weak ones have high energy. Large amounts of heat and/or light energy are released during the formation of strong bonds. Conversely, more energy is required to break strong bonds than weaker bonds.
Now that you have a better grasp on the two concepts of energy, you may have a shot at acing that test! Good luck!
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1. Chemistry 2: Types of Potential Energy, http://chemsite.lsrhs.net/chemKinetics/PotentialEnergy.html
2. Teaching the concept of chemical potential energy. Summer Research Program for Science Teachers. Retrieved from http://www.scienceteacherprogram.org/chemistry/linn04.html
3. Chemical energy, http://www.historyoftheuniverse.com/chemener.html
4. What is Energy?, http://www.uwsp.edu/cnr/wcee/keep/Mod1/Whatis/energyforms.htm