February 22, 2012

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 • Finish Practice Problems • Up-to-date Notebook • Friday is the Last Day to take Last Week’s Quiz • Last Week’s Work is due by Friday at the latest

2. Cornell Notes • Topic: Balancing Chemical Reactions • Date: 2/22/2012 MgO Mg + O2 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 + ___ O2 Mg = 1 O = 2 Example: 2 2 1 Coefficients x 2 = 2 x 2 = 2 x 2 = 2 x 1 = 2 Balanced Chem. Eqn. = 2 MgO 2 Mg + 1 O2 = Mg = O  +

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

6. Practice (on LEFT page) Counting Atoms: O2 O = 2 Fe2O3 Fe = 2 O = 3 2 NaOH Na = 2 O = 2 H = 2 2 Ca(NO3)2 Ca = 2 N = 4 O = 12

7. Practice (continued) Reactants ___ Ag + ___CuCl2 Ag = 1 Cu = 1 Cl = 2 Products ___ Cu + ___ AgCl Ag = 1 Cu = 1 Cl = 1 Example: 2 1 1 2 x 2 = 2 x 2 = 2 x 1 = 1 x 1 = 1 x 1 = 2 x 2 = 2