Equation, Chemical (Encyclopedia of Science)
A chemical equation is a shorthand method for representing the changes that take place during a chemical reaction. In describing the formation of water from its elements, a chemist could say, for example, that "two molecules of hydrogen gas combine with one molecule of oxygen to form two molecules of water." Or she could write the following chemical equation that contains the same information in a much more compact form:
2 H2 + O2 2 H2O
At the minimum, a chemical equation contains the chemical symbols and formulas for the elements and compounds involved in the reaction and the + and signs that indicate reactants and products. The term reactants refers to the substances present at the beginning of the reaction, and the term products refers to the substances formed in the reaction.
In the example above, the reactants are represented by the symbols H for hydrogen and O for oxygen. The product is represented by the formula H2O for water. The + sign indicates that hydrogen (H) has combined with oxygen (O) in the reaction. The indicates that the two have reacted with each other to form water.
Balancing chemical equations
One of the fundamental laws of chemistry is the law of conservation of matter. That law says that matter can be neither created nor destroyed...
(The entire section is 744 words.)
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