Balancing... One Step At A Time
Being able to balance chemical equations is a very important skill for students of chemistry, making this one of our most popular chemistry tutorials. All chemical calculations require you to work with a balanced equation. Here we will show you a simple, easy way to balance all chemical equations you will meet at introductory level chemistry courses.
A chemical equation is balanced when the number of atoms of each type on each side of the equation is the same. Which means if you have 12 hydrogens on the left hand side of the equation, you must have 12 hydrogens on the right hand side, if there are 4 oxygens on the left, there must 4 oxygens on the right, and so on. This is because of the law of conservation of mass - you can't make or destroy atoms during a chemical reaction. But you can't just add atoms at random to each side, you have to work with the molecules of the reactants.
The key to balancing chemical equations is to apply the rules below.
If you already know the rules, then try these worked examples for revision practice.
Balancing chemical equations isn't difficult, once you know the way to do it. Start by finding out how many atoms of each type are on each side of the equation. Some teachers recommend making a little table listing the numbers of each atom for the left hand side and for the right hand side.Example 1
Unbalanced Equation:- C3H8 + O2 ---> H2O + CO2
There are three carbons on the left, but only one on the right.
There are eight hydrogens on the left but only two on the right.
There are two oxygens on the left but three on the right.
Next, look for an element which is in only one chemical on the left and in only one on the right of the equation. (But it is usually a good idea to leave hydrogen and oxygen until you've done the others first.)
To balance that element, multiply the chemical species on the side which doesn't have enough atoms of that type by the number required to bring it up to the same as the other side. The number is called the coefficient.
If you have to multiply by, say, 2 1/2, do so, THEN multiply EVERYTHING on each side of the equation by two to get rid of the half.
We don't like having halves in equations, as you can't get half a molecule.
Now look for the next element or species that is not balanced and do the same thing.
Repeat until you are forced to balance the hydrogen and oxygens.
Thanks to The Wright Stuff and Sky-Web, http://www.sky-web.net/science/balancing_chemical_equations.htm