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Chemical Changes & Energy

Chemical Changes & Energy. All chemical changes also involve some sort of energy change. Energy is either taken in or given off as the chemical change takes place. Energy is the capacity to do work. Work is done whenever something is moved. Chemical Changes & Energy.

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Chemical Changes & Energy

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  1. Chemical Changes & Energy • All chemical changes also involve some sort of energy change. • Energy is either taken in or given off as the chemical change takes place.Energy is the capacity to do work. • Work is done whenever something is moved.

  2. Chemical Changes & Energy • Chemical reactions that give off heat energy are called exothermicreactions. • Chemical reactions that absorb heat energy are called endothermic reactions.

  3. Physical Changes & Energy • Freezing, condensation and deposition are exothermic. • Melting, evaporation and sublimation are endothermic.

  4. Assessment Questions Question State whether each of the following is an endothermic or exothermic process. 1. melting of ice endothermic 2. combustion of gasoline exothermic

  5. Assessment Questions Endothermic or exothermic? 3. Natural gas is burned in a furnace. exothermic 4. When solid potassium bromide is dissolved in water, the solution gets colder. endothermic

  6. Assessment Questions Endothermic or exothermic? 5. When concentrated sulfuric acid is added to water, the solution gets very hot. exothermic

  7. Graph of anEndothermic Reaction

  8. Graph of anEndothermic Reaction • In an endothermic graph, the products have greater energy than the reactants. The change in energy is a positive value. Products Reactants

  9. Graph of anExothermic Reaction

  10. Graph of anExothermic Reaction • In an exothermic graph, the reactants have greater energy than the products. The change in energy is a negative value. Products Reactants

  11. Conservation of Energy • Energy can be neither created nor destroyed in ordinary changes (not nuclear); it can only change form.

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