1. page 45
Warm Up Copy the following chemical equation for burning methane: CH₄ + 2O₂  CO₂ + 2H₂O How would this equation be written if you couldn’t use coefficients?
Date
Session #
Activity
Page #
11/16-17
“The Mass of Matter” text & ?’s
45-46
11/22, 28
Balancing a Chemical Equations 47
Balancing Equations Practice w/s 48
Homework:
H/W:
Write some one a note telling them why you are thankful for having them in your life
Sleep in, watch football, eat, take a nap, read, eat, watch football :)

2. CH₄ + 2O₂  CO₂ + 2H₂O
Mass of C atom = 12 Mass of O atom = 16 Mass of H atom= 1

3. 8.P.1 Understand the physical properties of matter and changes that occur when matter interacts in an open or closed container 8.P.1.4 Explain how the idea of atoms and a balanced chemical equation support the law of conservation of mass

4. Essential Question: How are interactions between matter described by the law of conservation of mass? How is the condition of the container significant in observing the law of conservation of mass?

5. page 46
Conservation of Mass
Matter is not created or destroyed. The mass of reactants is equal to the mass of products. How does a balanced chemical equation support the law of conservation of mass?

6. Law of Conservation of Mass
page 46
Law of Conservation of Mass
Requires that equations be balanced
Meaning:
The same elements are in the reactants as are in the products
The number of atoms of each type of element in the reactants must equal the number of atoms of each type of element in the product
To balance a chemical equation, you may only change the COEFFICIENTS, not the subscript

7. Law of Conservation of Mass
page 46
Law of Conservation of Mass
Requires that equations be balanced
Meaning:
The reactants have the same elements as the products
The number of atoms of each type of element in the reactants is the same as the number of atoms of each type of element in the product

8. Mass of reactants = mass of products
2Na + Cl2  2NaCl 10 g + 5g ___g P4 + 6Br2  4PBr3 8g + ____ g 20 g CH4 + O2  CO2 + H2O 6g + 7g 3g ____g

9. Steps to balance an equation
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Steps to balance an equation
Draw a line under the arrow to divide the reactants from the products
H2 + O2  H2O
2. Write down the symbol for each element on each side of the equation
H= O= H= O=

10. Steps to balance an equation
page 47
3. Using the distributive property, multiply the coefficients x the subscripts to find the number of atoms of each element
H2 + O2  H2O
H = 2 O= H=2 O =1
4. If it is not balanced, you may only change COEFFICIENTS. Guess and go from there, you may need to change coefficients a few times……….next steps we should take below?
H2 + O2  2H2O
H= O= H= O=2

11. For example, Hydrogen (H) and Oxygen (O)
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Why can’t you change the subscripts when you balance a chemical equation? 1. Compounds made of the same elements in a different ratio have different properties 2. Compounds made of the same elements in a different ratio are different substances
For example, Hydrogen (H) and Oxygen (O)
H2O and H2O2 are made of the same elements, but in a different ratio
H2O: boils at 100°C; melts at 32°C, universal solvent, pH=7
H2O2: boils at 108°C , melts at -33°C, antimicrobial, pH 6.2

12. Another example: C, H, O Isopropyl alcohol: C3H8O
boiling point is 82.5°C, freezing point is -88.5°C
flammable,
 Vinegar: CH3COOH
Boiling point is 100.6°C, freezing point is -2°C
Not flammable

13. Practice balancing these equations:
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Practice balancing these equations:
Cl2 + KI  KCl + I2 Al2O3  Al + O2 Na + O2  Na2O P + O2  P4O6

14. Complete balancing equations practice w/s.