Balancing Chemical Equations

Reactants Chemicals present at the start of a reaction Can be one or more than one

Products Chemicals that are formed during a chemical reaction Can be one or more than one

To simplify things, we usually write chemical reactions as equations. Chemical equations To simplify things, we usually write chemical reactions as equations. The reactants go on the left side The products go on the right side An arrow is used to show the direction of the reaction and is read as “yields” or “forms”

Law of Conservation of Mass/Matter Matter cannot be created nor destroyed. This means that the exact same atoms must be present at the beginning and the end of the reaction. It also means that all of the reactants combined must have the exact same mass as all of the products combined.

While we cannot create new matter, we can rearrange existing atoms by breaking and forming new bonds. So we must make sure that we have equal numbers and types of atoms in the reactants and the products.

Balancing Equations To balance an equation, you must first figure out how many of each type of atom you have on each side of the arrow

If they are already even… Then you are done. Don’t do anything else. SO3 + H2O  H2SO4 1S 1S 2H 2H 3+1 O 4O

If they are not even… Use coefficients to show how many of each compound you would need to make them even 2H2 + O2  2H2O 4H 4H 2O 2O

A couple of tips… 1) Start on the left and work your way over 2) Make sure to double check when you are done 3) If any polyatomic ions show up on both sides, treat them like a single element 4) Save pure elements for last because they are the easiest to adjust 5) Practice!