1. Balancing Equations

2. Law of Conservation of Mass This law states that mass is neither created nor destroyed during a chemical reaction. This relates to the balancing of equations because if this law is true, than the amount of atoms of an element on one side of the equation should be equal to the amount on the other side, however, sometimes they do not, therefore they are unbalanced. (H 2 + O 2 → H 2 O)

3. Let’s Try! K + Br ₂ = KBr (WHAT?!) 1 2 1 1 a.) First, we’ll count the number of atoms in each of the elements included. b.) Then, we add to the formula in ways that will balance the equation... Addition sign indicates that the Element is not currently bonded. K + Br ₂ = 2KBr…and recount the atoms. 1 2 2 2 c.) Then locate the areas that still need to be balanced 2K + Br ₂ = 2KBr

4. To Better Explain… Let’s compare the balancing of equations to a game of Tug of War. Naturally, if the teams are unbalanced 4 to 3, the team with 4 players will have an advantage. When you count the atoms on each side of the equation, consider them the players on a team competing in a game of Tug of War. Al + CuCl 2 → AlCl 3 + Cu Al + Cu Al Cl 2 Cl 3 +

5. One More Time… N 2 + H 2  NH 3 1.) Count up the number of atoms in each of the elements. 2 2 1 3 N 2 + H 2  2 NH 3 2.) Add in numbers that will change the number of atoms 2 2 2 6 and eventually even them out (using multiplication). N 2 + 3 H 2  2 NH 3 3.) Make final adjustments to make the amount of atoms 2 6 2 6 in each element equal of both sides. ***The Nitrogen atoms add up to 2 on both sides just like the Hydrogen atoms add up to 6 on both sides. This equation is now balanced.

6. Rules You cannot change the subscripts of an equation. Placing a number in front of the element will indicate multiplication of the elements included [2 Al (now 2 atoms are involved) or 2 Al 3 (6 atoms), etc.] When the elements are bonded they will appear as FeS, where as if they were not yet bonded they would be shown as Fe + S. When a sign indicates that the elements have yet to be bonded, a number appearing before the element will only apply to the one it is directly in front of (2 Fe + S)  only applies to iron (Fe)!

7. And We’re Done!… …Good Luck! H 2 + O 2  H 2 O

8. Bibliography Chemistry.about.com/cs/stoichiometry/a/aa042903a.htm. Sky-web.net/science/balancing_chemical_equations.htm.