1. Balancing Chemical Equations

2. QUIZ- List the different atoms and their quantity in the following compounds 1. NH 4 2. Ca(NO 3 ) 2 3. 2Mg 3 (PO 4 ) 2 4. Sodium phosphate BONUS: How many hydrogen atoms are in: 3Ca(NH 4 ) 2 + 3H 2 O

3. Chemical Equation Is a written expression of a chemical reaction (rxn) Rxn- a short hand way to write “reaction”

4. Reactants  Products Reactants make/produce products Reactants are the chemicals that are reacting Products are the chemicals that are being produced from the reaction The arrow means: to make or produce

5. Law of Conservation The number of atoms on the left hand side of the arrow (reactants) must equal the number of atoms on the right hand side of the arrow (products) When the number of atoms in the reactants equals the number of atoms in the product then it is a balanced equation.

6. Example Flour + eggs + milk + sugar + butter  cake “+” means to “combine with”, “add to”, “and”, etc H 2 + O 2  H 2 O Hydrogen is combined with Oxygen to produce water http://www.youtube.com/watch?v=_B735turDoM

7. H 2 + O 2  H 2 O Is not balanced. There are two H on the left and two H on the right. Good There are two O on the left and one O on the right. Bad ….not balanced So what can we do to make it balanced?

8. Coefficients Are whole numbers put in front of the molecules to balance equations. ***Leave space for the coefficients ___H 2 + ___O 2  ___H 2 O

9. 1. Write down the different atoms under the arrow 2H 2 2O 1 2. List how many of each atom you have in the reactants (left) and the products (right) 3. Check to see if the left side is the same as the right side.

10. Balancing Use coefficients…but remember, they change everything behind them AND YOU MUST MULTIPLY. ___H 2 + ___O 2  _2H 2 O 2H 2 4 2O 1 2 Now we have 4 Hydrogens (bad) and 2 Oxygens (Yay)

11. NEVER CHANGE THE LITTLE NUMBERS (subscripts)! So what can we do to the left side of the equation to make the oxygens balance (we need 4 oxygens on the left side now)? ___H 2 + ___O 2  _2H 2 O ___H 2 + __2_O 2  _2H 2 O By placing the “2” in front of O 2 we now have 4 oxygens on the left that balances the 4 oxygens on the right.

12. Now you try! A.___CH 4 + ___O 2  __CO 2 + ___H 2 O B.___ CaO + ___ NaCl  ___CaCl 2 + ___Na 2 O C.___ NH 4 + ____O 2  ____NO 2 + ___H 2 O http://www.sciencegeek.net/Chemistry/taters/EquationBalancing.htm (Homework worksheet… all blanks must have a number, so you will use “1” as a coefficient on the worksheet at times. Print to one note and show your work.