1. Catalyst – October 3+ 18, 2010 FUN GRAPH FRIDAY! 1. In what month do you think red light cameras were installed in Renton, WA? 2. What do you think happened to cause a decrease in citations (tickets) issued? Red light cameras were installed in Renton, WA and this graph shows the number of citations issued each month.

2. Today’s Agenda  Catalyst  Projects into Ms. Stroh  Scavenger Hunt  Notes  College Presentation  Exit Question GOOD LUCK TO ACT TAKERS!

3. Today’s Objectives  SWBAT begin to apply law of conservation of mass to chemical reactions by balancing chemical equations.

6. SCAVENGER HUNT!

7. Whiteboard Practice  How many total atoms of each element are in these compounds? AlCl 3 : Al = ? Cl = ? H 2 O: H = ? O = ? H 2 O 2 : H = ? O = ? KCl: K = ? Cl = ? Be 3 S 2 : Be = ? S = ? NH 4 NO 3 : N = ? H = ? O = ?

8. Balancing equations RULES!  Key Point #1: When balancing equations, never, Never, NEVER change subscripts, only coefficients!

9. Yo, Ms. Stroh  What is a coefficient? GOOD QUESTION!

10. Coefficient  A coefficient is a whole number that comes in front of the compound formula, never in the middle!  You multiply the coefficient to all the numbers in the compound 2 AlCl 3

11. Do you get it?  3 AlCl 3  How many atoms of each element do they have?  3 Aluminum atoms  9 Chlorine atoms

12. How many of each atom do we have now? 7 AlCl 3 4 H 2 O 6 H 2 O 2 5 KCl 2 Be 3 S 2 4 (NH 4 )NO 3

13. Why is the top equation wrong? You figure it out (5 min)  We never want to leave an equation written like this…  H 2 + O 2  H 2 O  We want to have it like this…  2 H 2 + O 2  2 H 2 O  WHY???

14. L-C-M!!!  Key Point #2: Chemical reactions MUST follow the Law of Conservation of Matter. What is the LCM?  Matter cannot be created or destroyed.  If 3 carbons are in the reactants of a reaction, then there darn well better be 3 carbons in the products of a reaction.

15. Balancing Chemical Reactions H 2 + O 2  H 2 O __H__ __O__ Write down elements.

16. Balancing Chemical Reactions H 2 + O 2  H 2 O __H__ __O__ How many are there?

17. Balancing Chemical Reactions H 2 + O 2  H 2 O _2_H_2_ __O__ How many are there?

18. Balancing Chemical Reactions H 2 + O 2  H 2 O _2_H_2_ _2_O_1_ How many are there?

19. Balancing Chemical Reactions H 2 + O 2  H 2 O _2_H_2_ _2_O_1_ Get number equal!

20. Balancing Chemical Reactions Try These: N 2 + H 2  NH 3 P 4 O 10 + H 2 O  H 3 PO 4 Ca 3 P 2 + H 2 O  Ca(OH) 2 + PH 3

21. Balancing Chemical Reactions Try These: N 2 + 3H 2  2NH 3 P 4 O 10 + H 2 O  H 3 PO 4 Ca 3 P 2 + H 2 O  Ca(OH) 2 + PH 3

22. Balancing Chemical Reactions Try These: N 2 + 3H 2  2NH 3 P 4 O 10 + 6H 2 O  4H 3 PO 4 Ca 3 P 2 + H 2 O  Ca(OH) 2 + PH 3

23. Balancing Chemical Reactions Try These: N 2 + 3 H 2  2NH 3 P 4 O 10 + 6H 2 O  4H 3 PO 4 Ca 3 P 2 + 6H 2 O  3Ca(OH) 2 + 2PH 3

24. COLLEGE PRESENTATION???

25. Exit Question  Balance the following equations: 1. __KClO 3 ---> __KCl + __O 2 2. __S + __O 2 ---> __SO 3 Leave Notes in Folder Please! GOOD LUCK ACT TEST TAKERS!!