Chemical Reaction Equations: General Information

Chemical Changes

Chemistry is the study of matter and the changes in matter. A chemical reaction is the process by which a substance changes into a different substance. During these transformations matter is not created nor does it vanish. A fundamental law about the nature of matter is the Law of Conservation of Mass. This law states that during any chemical change, mass is neither lost nor gained; matter is merely transformed from one substance into another.

We can understand why the Law of Conservation of Mass works if we think of Dalton’s model of the atom. Atoms are not created nor destroyed during chemical changes; they are just re-grouped into different compounds.

Chemical Reaction Equations

We use chemical reaction equations to describe the details of a chemical change. This type of shorthand gives a surprising amount of information in as few symbols as possible.

The information that this reaction equation conveys is

The identities of the substances involved listed by their formulae. If we know chemical nomenclature and symbols, we can also deduce the types of substances involved in the reaction (element versus compounds, and ionic, molecular, etc).
Which of the substances are the reactants (those present before the chemical change takes place) and which of the substances are the products (those formed during the chemical change).
The number of atoms/ions/molecules which make up these substances (indicated by coefficients and subscripts).
The states of matter for the substances in this particular reaction.

This site was last updated 09/14/06