Balancing Equations

Before we start, there are some things we all need to know

H 2 O means there are 2 Hydrogen and 1 Oxygen atoms in this compound. The subscript number AFTER a symbol tells us how many of that atom is in the molecule. (or compound)

2H 2 O means H 2 O and H 2 O Totaling 4 Hydrogen and 2 Oxygen atoms. The number in FRONT of the molecule is called the coefficient.

We can add molecules to the equation, but not single atoms. We can ONLY change the Coefficient of the molecule, NEVER the subscript.

Remembering the Law of Conservation of Mass: The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. Meaning that during a chemical reaction, matter is not created, nor is it destroyed. It is however rearranged. (This is huge in chemistry, be sure you know this…..KNOW IT)

Ok Here we go On a sheet of paper, lets work some equations together

Lets start by burning gas methane (CH 4 ) We know that this reaction consumes oxygen This produces water and carbon dioxide Below is an unbalanced chemical equation.

Start by counting the atoms in the reactants and products.

The carbons are happy and even, so are the hydrogens, but the oxygens are not balanced

Sure the easy way of solving this would be to change the O 2 to O 4, but that is changing the molecule, and thus cheating. Dont cheat, just add another O 2 molecule and life is good and all is happy.

Note that only the number of molecules has been balanced, and no molecules have been changed.

REMEMBER You can change the number of the molecules, but NEVER change just the number of atoms. (it changes the molecule) Remember, it is like using Legos

Any questions before we move on?

On a separate sheet of paper write down the following equations, and then balance it Good luck.

H 2 + O 2 H 2 O 2 H 2 + O 2 2H 2 O

Na + O 2 => Na 2 O 2 2Na + O 2 => Na 2 O 2

C + S 8 => CS 2 4C + S 8 => 4CS 2

C + O 2 => CO 2

Na + NaNO 3 => Na 2 O + N 2 10Na + 2NaNO 3 => 6Na 2 O + N 2

N 2 + O 2 => N 2 O 5 2N 2 + 5O 2 => 2N 2 O 5

K + B 2 O 3 => K 2 O + B 6K + B 2 O 3 => 3K 2 O + 2B

HCl + NaOH => NaCl + H 2 O

FeS 2 + O 2 => Fe 2 O 3 + SO 2 4FeS O 2 => 2Fe 2 O 3 + 8SO 2

H 3 PO 4 + KOH => K 3 PO 4 + H 2 O H 3 PO 4 + 3KOH => K 3 PO 4 + 3H 2 O

Brain going Squishie Squishie yet? Great Lets start our practice sheet