1. Balancing Act Atoms are not CREATED or DESTROYED during a chemical reaction. This is the LAW OF CONSERVATION OF MASS. There must be the SAME number of atoms on each SIDE of the EQUATION.

2. mass begin = mass end

3. reactants product mass of reactants = mass of products Conservation of Mass

4. Balancing Act To balance the chemical equation, you must add COEFFICIENTS in front of the chemical formulas in the equation. A coefficient is a number placed in front of a chemical formula in an equation that shows how many atoms are involved in a reaction. (A multiplier) Ex. 2MgO means there are 2Mg and 2O (2 is the coefficient)

5. Conservation of Mass

6. Subscripts A subscript is a number written to the right of a chemical symbol and slightly below it. It tells how many atoms of that element. Ex. H 2 O would be 2 hydrogen and 1 oxygen You cannot ADD or CHANGE subscripts!

7. reactants product mass of reactants = mass of products Conservation of Mass

9. Example 1

10. Example 2

14. Iron + Oxygen -----> Rust 100 g + ? g ------> 143g mass reactants = mass products What is the mass of Oxygen? Conservation of Mass

15. What chemical equation is this?

16. http://www.neok12.com/php/watch.php?v=zX567d4e457d7 37d75667b0a&t=Law-of-Conservation http://www.neok12.com/php/watch.php?v=zX780d5e78067 64057657b45&t=Law-of-Conservation Brain Pop http://www.brainpop.comhttp://www.brainpop.com Conservation of Mass

17. Balancing Act Homework

19. Balancing Act Homework ANSWERS