1. UNIT 1 Matter Day 24 October 3, 2017
Law of Conservation of Mass
Earth and Environmental Science

2. Place your Venn diagram in the box on the front lab table.
October 3, 2017
Place your Venn diagram in the box on the front lab table.

3. Plan for today:
Inquiry Lab on the Law of Conservation of Mass
Lesson on Law of Conservation of Mass- balancing chemical equations:
*notes/discussion
*video
*practice

4. Chemistry Unit Test Friday, Oct. 13th
Homework:
Quiz next Monday over elements, compounds, and mixtures/Law of Conservation of Mass/Balancing Chemical Equations
Chemistry Unit Test Friday, Oct. 13th

5. E.Q. Page 11
What happens to atoms during chemical reactions?

6. Inquiry lab - “law of conservation of mass/matter”

7. Let’s take a few notes about the law of conservation of mass/matter

8. Copy these 3 examples. Chemical Formulas
Def. Chemical formula is a combination of chemical symbols and numbers to represent a substance.It shows how many atoms of each kind of element are present in a molecule.
Subscript: a number written to the lower right of a chemical symbol. It tells how many atoms of that element are present.
Copy these 3 examples.

9. Chemical Formulas
Def. Chemical formula is a combination of ____________ ___________and ____________ to represent a ___________.It shows how many __________ of each kind of ___________ are present in a ____________.
Subscript: a number written to the _________ __________ of a chemical ___________ . It tells how many ___________ of that element are
present.

10. chemical Equations
Def. Use chemical symbols and formulas to describe a chemical reaction.
Ex: Copy this
Chemical equation.
C and O2 are the reactants. CO2 is the product.
yields

11. Chemical Equations
Def. - Use chemical ____________ and ____________ to describe a ____________ ____________.

12. Law of Conservation of Mass
Def. This law states that matter(mass) CANNOT be created or destroyed in ordinary physical or chemical changes.
The total mass of the reactants equals the total mass of the products.
This can be proven in a closed system… one in which nothing enters or leaves the system.

14. Law of Conservation of Mass
Def. This law states that ______________ CANNOT be _____________ or _____________ in ordinary ______________or ________________ ________________.
The total __________________________________________
______________________________________________________.
This can be proven in a __________ ___________…one in which nothing enters or leaves the system.

15. Let’s look at the Law of Conservation of Mass and Chemical Equations presented Brainpop’s way.
Brainpop - Law of Conservation of Matter

16. Now let’s learn how to balance chemical equations.
A Quick Review
elements
Chemical symbols represent __________.
compounds
Chemical formulas represent __________.
Chemical equations represent __________.
chemical reactions.
Now let’s learn how to balance chemical equations.

17. Now let’s learn how to balance chemical equations.
A Quick Review
Chemical symbols represent __________.
Chemical formulas represent __________.
Chemical equations represent __________.
Now let’s learn how to balance chemical equations.

18. Before we practice balancing equations, let’s practice counting atoms.
Practice Counting Atoms worksheet

19. Let’s learn how to balance chemical equations.
Remember that the Law of Conservation of Mass/Matter states that in a chemical reaction, NO atoms are gained or lost. They just get rearranged to form NEW SUBSTANCES.

20. *Coefficient: a number that is placed in front of a chemical symbol or formula in order to balance a chemical equation. Subscripts CANNOT be changed to balance an equation. Why?
H2O 2H20 -2 molecules of water
CO2 4CO2 – 4 molecules of carbon dioxide
C6H12O6

21. *Coefficient: a number that is placed ____________ a chemical _________ or _________ in order to __________ a chemical ___________. Subscripts __________ be _________ to balance an equation. Why?
H2O 2H20 -2 molecules of water
CO2 4CO2 – 4 molecules of carbon dioxide
C6H12O6

22. More O2 in the reactants.
Count to be sure the number of atoms of each element is the same in the reactants and products.

23. How to Balance Chemical Equations: 3 Simple Steps
Step 1: Count the number of atoms for each element on both sides of the equation. Look for elements that are not balanced.
Ex. Mg O2 MgO
Mg- Mg-
O- O-
_____ is unbalanced.

24. Step 2: Add a coefficient in front of the formula that contains the unbalanced element(s). The O was unbalanced. Place a coefficient 2 in front of the MgO. ***Note: This may throw off the balance of other elements, so you have to keep working with it.
Ex. Mg O2 __ MgO
This will balance the O, but unbalance the Mg. So…add another coefficient 2 in front of the Mg in the reactant.
Ex. ___Mg O2 2 MgO
*This should balance the Mg but be sure to do Step 3.

25. Step 3: Check the number of atoms on both sides of the equation to be certain they are balanced.
2Mg O 2MgO
Mg- Mg-
O- O-
Is it balanced? If so, you have supported the Law of Conservation of Matter (Mass).

26. How does balancing equations illustrate and support the Law of Conservation of Mass/Matter?
*Because they require that you have the same mass after the reaction as you do before the reaction. This means…
*The # and type of atoms are the same in the reactants and products (just in different combinations)
*Although the state of matter of the products may be different from the reactants, the overall mass doesn’t change.

27. Let’s look at Chemical Equations presented Brainpop’s way.
Brainpop-Chemical Equations

28. Before we practice balancing equations, let’s practice counting atoms.
Practice Counting Atoms worksheet

29. Let’s practice balancing some chemical equations
Let’s practice balancing some chemical equations. “Balancing Act” practice sheet.
Use pencil. You may have to change coefficients a few times.

30. In a chemical reaction, no atoms are gained or lost
In a chemical reaction, no atoms are gained or lost. They just get rearranged.
Because this Law of Conservation of Matter (Mass) has been proven, chemical equations (which represent a chemical reaction) MUST be balanced (same number of atoms on both sides).
mass of the reactants=mass of the products.

31. Wrap-up:
Any questions?