1. Balancing Chemical Equations

2. Warm Up What is a chemical reaction?
What are the reactants? What are the products?
EQ: How do we balance chemical equations?
HOT Q1: What is a chemical reaction?
HOT Q2: What does the law of conservation of mass state?
HOT Q3: What are the steps for balancing chemical equations?

3. Agenda Warm Up/Objective How ‘Bout Them Apples Chemical Reaction Notes
Chemical Reaction Practice
Worksheet 7.2
Exit Ticket

4. Chemical Reaction Notes
- a process that leads to the transformation of one set of chemical substances to another

5. Chemical Reaction Notes
2. Two Sides of the Chemical Equation
Reactants –
Products –
___Li + ___Br2  ___ LiBr
Reactants
Products

6. What’s up with the apples?

7. How ‘Bout Them Apples

8. Chemical Reactions  Br Br Br Br Li Li Li Li

9. For the rest of today, we will be balancing chemical equations.
This will seem like a bunch of rules a chemist made up unless you understand the following concepts.

10. Chemical Reaction Notes
1. Law of Conservation of Mass
2. Chemical reactions MUST BE BALANCED
The number of atoms on the reactant side and the product side must be EQUAL
But how do we count the number of atoms?

11. Counting Atoms Rules 3P6Cl3
1. Subscripts apply to the element immediately before it
Ex) MgCl2 #Mg ____ #Cl_____
2. Coefficients multiply the entire molecule
Ex) 2C6H2 #C___ #H____

12. 3. If there are parentheses, the subscript multiples everything inside the parentheses
Ex) 3Be(NO3)2 #Be___ #N____ #O____

13. Counting Atoms 1. H2SO4 2. Ca(OH)2 3. NaCl 4. (NH3)3PO4 5. 3H2O
How many atoms of each element are in the following molecules?
1. H2SO4
2. Ca(OH)2
3. NaCl
4. (NH3)3PO4
5. 3H2O

14. To decide if an equation is balanced, compare the number of atoms of each element that appear on each side of the equation. If the number of atoms is equal then the equation is balanced, if not equal than the equation is not balanced
Ex) N2 + 3 H2  2 NH3
Is it balanced?

15. You Try!
C3H8 + 5 O2  3 CO2 + 4 H2O
Is is balanced?

16. Ok, cool.
BUT HOW DO WE BALANCE THESE BAD BOYS????!!!

17. When balancing… Step 1: Draw a line between products and reactants
Step 2: Tally up atoms of each element on each side
Step 3: Change coefficients to start balancing
(never change subscripts!)
Step 4: Recalibrate each time you change a coefficient
Step 5: CHECK YOUR WORK!

18. Balancing Chemical Reactions
Notes
Balancing Chemical Reactions
Ex 1: ____N2 + ____H2  ___NH3

19. Balancing Chemical Reactions
Notes
Balancing Chemical Reactions
Ex 2: ____FeO  ____Fe ____O2

20. The best way to learn this is to practice.
With a partner, balance the following equations:
____NO + ____O2  ___NO2
____H2 + ____Cl2  ___HCl
____Fe + ____Cl2  ___FeCl3
4. ____CH4 + ____O2  ___CO2 + ___H2O

21. Partner Practice
1. ____NO + ____O2  ___NO2

22. Partner Practice
2. ____H2 + ____Cl2  ___HCl

23. Partner Practice
3. ____Fe + ____Cl2  ___FeCl3

24. Partner Practice
4. ____CH4 + ____O2  ___CO2 + ___H2O

25. Partner Practice 5. ____ K + ____ Cl2  ____ KCl
6. ____ N2 + ____ F2  ____ NF3

26. Independent Practice
For the rest of class, work on (and complete, if possible) Worksheet 6.1 If you get done: come and see me. If you are done, I will have you check your answers against my answer key. If you get any wrong, you must go back and fix them. If you get done with that: You may help a neighbor for beast mode status.

27. Exit Ticket Balance the following equations: ___Na + ___Cl2  ___NaCl
___Al + ___HBr  ___AlBr3 + ___H2

28. ___GaF3 + ___ Cs  ___ CsF + ___ Ga

29. ___ CF4 + ___Br2 ___CBr4 + ___F2

30. ___SeCl6 + ___O2 ___SeO2 + ___Cl2