1. Physical Science Chapter 10.1 Part 2

2.  Think, discuss with partner, discuss with class  1) What are signs of a chemical change? DO they always mean there is a chemical change?  2) What does this chemical equation tell you? CH 4 +2O 2 -> CO 2 +2H 2 O

3.  The reaction combines hydrogen and oxygen molecules. For help -> http://misterguch.brinkster.net/eqnbalance.htmlhttp://misterguch.brinkster.net/eqnbalance.html Or http://phet.colorado.edu/en/simulation/balancing-chemical-equations

4.  Count the atoms to see if there are the same number of each type of atom on the reactant and product sides of the equation. Since there is one more oxygen atom on the reactant side than there is on the product side, the reaction equation is not balanced.

5.  A balanced chemical equation has the same number of each type of atom on the product side and the reactant side.

7.  Write the unbalanced equation  NaOH + H 2 SO 4  Na 2 SO 4 + H 2 O  Draw boxes around all chemical formulas  NaOH + H 2 SO 4  Na 2 SO 4 + H 2 O  Make an element inventory ElementBeforeAfter Na12 O55 H32 S11

8.  Write numbers in front of the boxes until the inventory before and after balance  2 NaOH + H 2 SO 4  Na 2 SO 4 + H 2 O ElementBeforeAfter Na22 O65 H42 S11

9.  You can change the coefficient on both sides - - but not the chemical formulas  2 NaOH + H 2 SO 4  Na 2 SO 4 + 2 H 2 O ElementBeforeAfter Na22 O66 H44 S11

10.  NaCl + BeF 2  NaF + BeCl 2

11. ElementBeforeAfter Na11 Cl12 Be11 F21

12.  2 NaCl + BeF 2  NaF + BeCl 2  Keep going ElementBeforeAfter Na21 Cl22 Be11 F21

13.  2 NaCl + BeF 2  2 NaF + BeCl 2  Done! ElementBeforeAfter Na22 Cl22 Be11 F22

14.  Remember lowest common denominators - they can help  Coefficients are whole numbers  Don’t do this in your head – you are leaning a technique to apply to more complicated chemical equations.

15.  Chemical Equation Worksheet  Due end of class