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It is important that chemistry students are able to write balanced equations, be able to interpret equations that other people have written, and also to know how to predict specific reactions.
The difference between a formula and an equation is that a formula shows chemistry that is at a standstill, whereas equation show chemistry in action. Equations are responsible for showing the reactants which enter into a reaction; products that are formed by the reaction; and the amounts of each substance and each substance that is produced.
There are some things that it is vital that you remember when you are writing chemical equations and they are the symbols. You will be able to find all of these on this site: www.files.chem.vt.edu/RVGS/ACT/notes/Types_of_Equations.html
If you are writing equations you need to remember that you need to write the formula (or formulas) for any substance that is coming into the reaction. You need to put a plus sign (+) between the formulas where they are needed, and to put the yield arrow after the final one.
Once you have decided which of the four types of equations is applicable to the reaction that you are thinking about you can write down the correct formulas for all of the formed products to the right of the arrow.
Remember to make sure that each formula is correct before you write it down because it can never be changed while you are balancing the equation. A chemical reaction must be accountable for every single atom that is used. This is an application of the Law of Conservation of Matter and means that atoms in a chemical reaction are not created or destroyed.