Catalyst – April , 2013 HW OUT! GRAB A CALCULATOR! 1. How many grams are in 4.5 moles of CaBr 2 ? (Hint: use MOLAR MASS) 2. How many moles are in 3 x atoms of Lithium? (Hint: use AVOGADRO’S #)

Today’s Agenda  Catalyst  Ion Game!  Molar Conversion Review (20 min)  Balancing Chemical Equations Part 1  Practice! Practice! Practice!  Exit Question HW: To Be Determined!!!

Yesterday’s Exit Question 1. What information do we get from Avogadro? 1 mole = 6.02 x particles How to convert between moles and atoms 2. What is the molar mass of Helium? 4.00 g/mol

Today’s Objectives  SWBAT apply the Law of Conservation of Matter to chemical equations.  SWBAT balance simple chemical equations.

LESSON TITLE: BALANCING CHEMICAL EQUATIONS (Part 1)

4 minutes! PARTNER WORK!

Let’s Look at a Chemical Reaction 1 RIGHT! WRONG!

Without the Coefficients…

With the Coefficients… 1

Why Balance Equations?  Key Point #1: Balancing a chemical equation refers to establishing the mathematical relationship between the quantity of reactants and products. The quantities are expressed as moles.

Let’s Take Another Look… 2 x g = g 2 x g = g 1 x x Mass Products = g g g Mass Reactants = g NOT EQUAL!

Oh Heyyyy….AWESOME! BOOYA! 2 x g = g 6 x g = g Mass Reactants and Mass of Products = g 1 NOT EQUAL! EQUAL!

L-C-M!!!  Key Point #2: Chemical reactions MUST follow the Law of Conservation of Mass/Matter, so the mass of the reactants should equal the mass of the products. The Law of Conservation of Mass/Matter (LCM) states that matter cannot be created or destroyed.

Balancing equations RULES!  Key Point #3: When balancing equations, never, Never, NEVER change subscripts! ONLY CHANGE COEFFICIENTS!

Coefficient  A coefficient is a whole number that comes in front of the compound formula, never in the middle! (stands for atoms or moles)  You multiply the coefficient to all the numbers in the compound 2 AlCl 3

3 minutes! PARTNER WORK!

Steps to Balancing Equations 1. TAKE INVENTORY! List elements. Count on both sides. 2. BALANCE! Add coefficients and multiply. Re-count elements. 3. CHECK YOUR WORK!

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

Balancing Chemical Reactions H 2 + O 2  H 2 O __H__ __O__ Count the atoms of each element.

Balancing Chemical Reactions H 2 + O 2  H 2 O _2_H_2_ __O__ How many “H”s are there?

Balancing Chemical Reactions H 2 + O 2  H 2 O _2_H_2_ _2_O_1_ How many “O”s are there?

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

Balancing Chemical Reactions Try These: 1N 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

Balancing Chemical Reactions Try These: 1N 2 + 3H 2  2NH 3 1P 4 O H 2 O  4H 3 PO 4 Ca 3 P 2 + H 2 O  Ca(OH) 2 + PH 3

Balancing Chemical Reactions Try These: 1N H 2  2NH 3 1P 4 O H 2 O  4H 3 PO 4 1Ca 3 P 2 + 6H 2 O  3Ca(OH) 2 + 2PH 3

BALANCING WORKSHEET!!! The more you do, the more you learn!

Exit Question  Balance ONE of the following equations: 1. __KClO 3 ---> __KCl + __O 2 2. __S + __O 2 ---> __SO 3 HW: Study Ions – Quiz tomorrow! Bring back Progress Reports!