How Is Energy Used in Chemical Reactions?
Energy refers to a force's ability to cause objects to move. Chemical reactions result in the production of new substances and are always accompanied by a change in thermal energy. Thermal energy, or heat energy, refers to the kinetic energy found in molecules as they move around.
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Overview of Energy
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In science, energy refers to an object's ability to do work. Work is not defined as doing something to achieve a goal but as the result of a force acting on an object and causing it to move. For example, if you throw a ball, you are doing work on the ball because you are causing it to move.
There are two kinds of energy: potential and kinetic energy. Potential energy is stored energy. For example, a weight sitting on a shelf has a high amount of potential energy because it would generate a large force if it were to fall. Kinetic energy is the energy of motion. Billiard balls rolling around the table after a pool shot are using kinetic energy.
Chemical reactions release chemical energy. Chemical energy is a special kind of potential energy found in foods and fuel. This energy must be converted into a usable form via chemical reactions.
Conservation of Energy
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The Law of Conservation of Energy says that energy cannot be created nor destroyed; it can only be converted from one form to another. This is important to remember when thinking about chemical reactions. We often say that a reaction "gives off" heat, but this is not exactly true. A chemical reaction does not cause a substance to lose energy; it converts the energy into a different form, such as heat.
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Chemical Reactions
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Chemical reactions are interactions between different elements that result in the creation of new substances. Chemical reactions are always accompanied by a change in energy. Some chemical reactions, called exothermic reactions, release energy, while other reactions, called endothermic reactions, absorb energy from the environment.
Exothermic Reactions
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In exothermic reactions, the products have less potential energy than the reactants because energy has been released, usually in the form of heat. Lighting a propane barbecue grill is an example of an exothermic reaction. When you light the propane, heat is released into the environment along with water and carbon dioxide. The propane and oxygen involved in the reaction have more potential energy than the carbon dioxide and water produced.
Endothermic Reactions
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In endothermic reactions, the products have more potential energy than the reactants because energy has been absorbed. The process of photosynthesis is an example of an endothermic reaction. In this reaction sunlight is absorbed by the plant and reacts with carbon dioxide and water to make glucose and oxygen.
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References
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