Introduction to Chemical Equations
As we begin this lesson I would like to point out a few very basic bits of information. These are things we won't dwell on, but I do want to make sure you know what they are.
First, there is the distinction between chemical reactions and chemical equations. A chemical reaction is what really happens. For example, when magnesium burns, a shiny, lustrous piece of flexible metallic ribbon is heated in the presence of a colorless, transparent gas and changes into a white-to-grey, opaque, crumbly, powdery solid. That is a chemical reaction. The chemical equation is a way of representing that reaction by using formulas to represent each of the chemicals involved.
When water is electrolyzed, we can write that H2O becomes H2 and O2. "H2O H2 + O2" is an equation that represents the reaction. The reaction itself is the formation of two colorless gases, hydrogen and oxygen, when an electric current is passed through the colorless transparent liquid, water. It is important that you realize the distinction between reactions and equations.
Second, there are a few important terms that you may already know, but let's take this time to formalize it. The term "reactant" is the same as the term "reagent." It refers to each of the chemicals that are reacting with one another; in other words, what you have when you start the reaction. The chemicals that you get as the reaction proceeds are called the "products." So, as a chemical reaction proceeds, you start with reactants and you end up with products. When magnesium burns, you have magnesium as one reactant or reagent and oxygen as the other reactant or reagent. The magnesium oxide that you end up with is the product.
There are three types of equations with which you need to become familiar. They are word equations, skeleton equations and balanced equations. They are discussed in the pages of this section.
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