Purpose:
The previous lab involved determining the formula of ionic compounds by balancing charges using subscripts. Now, atoms, molecules and compounds can be combined to react and form new products. These reactions must also be balanced. The number of atoms before the reaction occurs (reactants) must equal the number of atoms after the reaction (products). An equation is balanced using only the coefficients.

Procedure:

1. Check the subscripts (e.g. Al₂O₃) on each molecule/compound for correctness first. In boxes with missing compounds (?) you must determine the compound by charges and check the subscripts.
2. Once the subscripts are checked and are correct, DO NOT ALTER THEM AGAIN
3. To balance go back and forth repeatedly on both sides of the equation and adjust the COEEFICIENTS ONLY
   (e.g. 4Al + 3O₂ => 2Al₂O₃ ) until there are the same number of each atom on both sides of the equation.
4. You might go too far in your balancing efforts yet the chemical equation will still balance (e.g. 8Al + 6O₂ => 4Al₂O₃ ). Just go back and check the coefficients to see if you can divide out a common factor (i.e. 2 in the previous example).
5. Combustion reactions can be tricky at times to balance. Always balance the carbon atoms first, then the hydrogen, saving the oxygen for last.
6. If a fractional coefficient is required to balance oxygen (e.g. 3.5 O₂ ) you should go back and double the values of all the coefficients.
7. Make sure there are no single atom products or reactants from the diatomic family (i.e. H₂, N₂, O₂, F₂, Cl₂, Br₂ )

Problems: