Do Now (done in your tracker)• Name the following compounds: • 1. MgPO4

• 2. PO3 • 3. NO2 • 4. CaCl2• 5. MgO2

• Today’s Lesson Topic: Balancing Chemical Equations

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

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?

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.

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!

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 + O2 Fe2O3

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

Word Equations

• ExampleMethane + Oxygen Carbon dioxide +

Water

• The arrow means yields, gives, or reacts to produce.

• How many elements are in the following compound?

Na2CO3

Let’s Check (Review)…

Practice

• Identifying chemical formulas

Rules for balancing1. 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)

NEVER

• 1. Change a subscript to balance an equation.

• 2. If you change the formula you are describing a different reaction.

3. H2O is a different compound than H2O2

4. Never put a coefficient in the middle of a formula• 2 NaCl is okay, Na2Cl is not.

Practice A1

__ H2 + ___ O2 ___ H2O

__ SO2 + ___ O2 ___ SO3

Answers

2 H2 + O2 2 H2O

2 SO2 + O2 2 SO3

Try to balance this reaction—Practice A2: __Al(OH)3(s) + __H2SO4(aq) __Al2(SO4)3(aq) + __H2O(l)

Al

S

H

O

Al

S

H

O

1

1

5

7

2

3

2

13

12

18

8

2 3 6

2

10

3

12

18

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.

• 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.

Practice A3:

• Balance these equations:

• __ Mg + __ O2 → __ MgO• __ KClO3 → __ KCl + __ O2 • __ Cu + __ AgNO3→ __ Cu(NO3)2 + __ Ag• __KOH + __ H3PO4 → __ K3PO4 + __ H2O  

ANSWERS

• 2 Mg + O2 → 2 MgO• 2 KClO3 → 2 KCl + 3 O2 • Cu + 2 AgNO3→ Cu(NO3)2 + 2 Ag• 3 KOH + H3PO4 → K3PO4 + 3 H2O  

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?