Characteristics of a Chemical Change

13 Distinguish between reactants and products in a chemical equation. 

In Section 2.3 we said that a chemical change occurs when the chemical identity of a starting substance is destroyed and a new substance forms. Chemists describe such a change hy writing a chemical equation. The formulas of the beginning substances, called reactants, are written to the left of an arrow that points to the formulas of the substances formed, called products. The equation for the reaction of the element carbon with the element oxygen to form the compound carbon dioxide is 

Notice how the equation is a symbolic representation of the essence of a chemical change The carbon (C) and oxygen (O2) present at the beginning are destroyed, and a new substance, carbon dioxide (CO2), forms. 

The decomposition of water (see Fig. 2.7) is another example of a chemical change. The starting compound, water (H2O), decomposes into its elements, hydrogen (H2) and oxygen (O2). The equation is 

15 Distinguish between potential energy and kinetic energy. 

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Characteristics of a Chemical Change Conservation Laws and Chemical Change... 

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