1. February 22, 2012 AGENDA: 1 – Bell Ringer & Part. Log 2 – Return Quiz 3 – Cornell Notes: Balancing Chemical Reactions 3 – Work Time Today’s Goal: Students will be able to balance chemical reactions. Homework 1. Finish Practice Problems 2. Up-to-date Notebook 3. Friday is the Last Day to take Last Week’s Quiz 4. Last Week’s Work is due by Friday at the latest

2. Cornell Notes  Topic: Balancing Chemical Reactions  Date: 2/22/2012 MgO  Mg + O 2 Reactants  Products Why do we balance chemical equations ? Things reacting Things produced

3. Cornell Notes (continued) Law of Conservation of Mass/Matter = = = Mass of reactants Mass of products # of each element of the reactants # of each element of the products

4. Cornell Notes (continued) Reactants ___ MgO Mg = 1 O = 1 Products ___ Mg + ___ O 2 Mg = 1 O = 2 Example: x 2 = 2 x 1 = 2 221 Balanced Chem. Eqn. = 2 MgO  2 Mg + 1 O 2 = Mg = O  + Coefficients

5. Cornell Notes (continued) “How to Balance” Steps: 1. Draw a line between reactants & products. 2. Count up all atoms of reactants & products. 3. Determine multiplier (coefficient)  LCD. 4. Place multiplier (coefficient) in front of compound. 5. Repeat if necessary.

6. Practice (on LEFT page) Counting Atoms: O 2 O = 2 O2O2 Fe 2 O 3 Fe = 2 O = 3 Fe 2 O 3 Fe = 2 O = 3 2 NaOH Na = 2 O = 2 H = 2 2 NaOH Na = 2 O = 2 H = 2 2 Ca(NO 3 ) 2 Ca = 2 N = 4 O = 12 2 Ca(NO 3 ) 2 Ca = 2 N = 4 O = 12

7. Practice (continued) Reactants ___ Ag + ___CuCl 2 Ag = 1 Cu = 1 Cl = 2 Products ___ Cu + ___ AgCl Ag = 1 Cu = 1 Cl = 1 Example: x 2 = 2 x 1 = 1 x 2 = 2 x 1 = 1 2121 x 1 = 2 x 2 = 2