2. Do Now (done in your tracker) Name the following compounds: 1. MgPO 4 2. PO3 3. NO2 4. CaCl2 5. MgO2 Today’s Lesson Topic: Balancing Chemical Equations

3. Class Updates Final exams are next week… we have to work VERY hard this week, but we can do it! Binder checks are coming, I want to give you credit for your notes – so make sure you’re updating you TOC and adding your guided notes EVERY CLASS period

4. Objective & Essential Questions SWBAT be able to apply the Law of Conservation of Mass to balance chemical equations. What is a balance chemical equation and why is it important part of chemical reactions?

5. A small window in how we survive… Metabolism! C6H12O6 + 6O2  6CO2 + 6H20 +ATP + Heat C6H12O6 = Glucose Metabolism Occurs in cells ATP provides energy for cells This very small reaction is ESSENTIAL for our survival and being balanced is key.

6. Law of Conservation of Mass The mass you start with has to equal the mass that you end with. Because mass cannot be created or destroyed in a system. This is “balanced” part!

7. Chemical Equations A chemical equation is a representation of a chemical reaction; the formulas of the reactants (on the left) are connected by an arrow with the formulas of the products (on the right). Skeleton Equation does not indicate the amounts of reactants or products. –No coefficients!!! Example Fe + O 2  Fe 2 O 3

8. All chemical reactions have two parts Reactants - the substances you start with (the ones reacting) Products- the substances you end up with (the ones produced) The reactants turn into the products. Reactants  Products

9. Word Equations Example Methane + Oxygen  Carbon dioxide + Water The arrow means yields, gives, or reacts to produce.

10. How many elements are in the following compound? Na 2 CO 3 Let’s Check (Review)…

11. Practice Identifying chemical formulas

12. Rules for balancing 1. Write the correct formulas for all the reactants and products 2. Draw boxes around all chemical formulas and label the reactants and products with a “R” and “P” 3. Make ‘inventory’ of the atoms you have present 4. Write numbers in front of each of the boxes until the inventory of each element is the same on both sides (ALWAYS double check your work)

13. NEVER 1. Change a subscript to balance an equation. 2. If you change the formula you are describing a different reaction. 3. H 2 O is a different compound than H 2 O 2 4. Never put a coefficient in the middle of a formula 2 NaCl is okay, Na2Cl is not.

14. Practice A1 __ H 2 + ___ O 2  ___ H 2 O __ SO 2 + ___ O 2  ___ SO 3

15. Answers 2 H 2 + O 2  2 H 2 O 2 SO 2 + O 2  2 SO 3

16. Try to balance this reaction—Practice A2: __Al(OH) 3 (s) + __H 2 SO 4 (aq)  __Al 2 (SO 4 ) 3 (aq) + __H 2 O(l) Al S H O Al S H O 1 1 5 7 2 3 2 13 12 18 8 236 2 10 3 12 18

17. Pre-Lab & Lab Do continued on with the visual aids you and partner have show completion on the pre-lab (which I will sign) Explicit instructions must be followed or you will not be able to participate.

18. A. Try to balance the equation first. Then, try to model the equation using beads. b. A pipe cleaner should be used to string beads onto in order to represent formula units or molecules. Pure elements (atoms) DO NOT need a pipe cleaner. c. One of the lab partners should use his/her beads to simulate the left side of the balanced equation on a piece of paper, and the other person should simulate the right side on a separate piece of paper. DO NOT split up molecules/formula units! This is why they are on a pipe cleaner. e. Make sure that there are the same number of pieces of each kind and color on each side of the equation. f. When you and your lab partner have completed an equation, have your instructor check the balanced equation and the candy arrangement to verify that everything is correct.

19. Practice A3: Balance these equations: __ Mg+ __ O 2 → __ MgO __ KClO 3 → __ KCl + __ O 2 __ Cu + __ AgNO 3 → __ Cu(NO 3 ) 2 + __ Ag __KOH + __ H 3 PO 4 → __ K 3 PO 4 + __ H 2 O

20. ANSWERS 2 Mg+ O 2 → 2 MgO 2 KClO 3 → 2 KCl + 3 O 2 Cu + 2 AgNO 3 → Cu(NO 3 ) 2 + 2 Ag 3 KOH + H 3 PO 4 → K 3 PO 4 + 3 H 2 O

21. Exit Ticket Balance the following: 1. HgO  Hg + O2 2. H2 + O2  H20 3. What is the Law of Conservation of mass? 4. What is C6H12O6?