1. Section 2: Changes in Matter
Matter can undergo physical and chemical changes. K
What I Know W
What I Want to Find Out L
What I Learned

2. Essential Questions
What is a physical change and what are several common examples?
What defines a chemical change? How can you recognize a chemical change?
How does the law of conservation of mass apply to chemical reactions?
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Changes in Matter

3. Good Morning! Bell Work 16 more wake-ups until Fair Day!!!!
physical change
phase change
chemical change
law of conservation of mass
Changes in Matter
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4. Physical Changes
A change that alters a substance without changing its composition is known as a physical change.
A phase change is a transition of matter from one state to another.
Boiling, freezing, melting, and condensing all describe phase changes in chemistry.
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Changes in Matter

5. Chemical Changes
A change that involves one or more substances turning into new substances is called a chemical change.
Decomposing, rusting, exploding, burning, or oxidizing are all terms that describe chemical changes.
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Changes in Matter

6. Law of Conservation of Mass
The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction, it is conserved.
The mass of the reactants equals the mass of the products.
massreactants = massproducts
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Changes in Matter

7. CONSERVATION OF MASS Problem Response KNOWN UNKNOWN
mmercury(II) oxide = g
moxygen = ? g
mmercury = 9.26 g
Use with Example Problem 1.
Problem
In an experiment, g of red mercury(II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of oxygen formed in the reaction?
SOLVE FOR THE UNKNOWN
State the law of conservation of mass.
Massreactants = Massproducts
mmercury(II) oxide = mmercury + moxygen
Solve for m oxygen.
moxygen = mmercury(II) oxide − mmercury
Substitute mmercury(II) oxide = g and mmercury = 9.26 g.
moxygen = g − 9.26 g
moxygen = 0.74 g
Response
ANALYZE THE PROBLEM
You are given the mass of a reactant and the mass of one of the products in a chemical reaction. According to the law of mass conservation, the total mass of the products must equal the total mass of the reactants.
Changes in Matter
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8. CONSERVATION OF MASS EVALUATE THE ANSWER
The sum of the masses of the two products equals the mass of the reactant, verifying that mass has been conserved. The answer is correctly expressed to the hundredths place, making the number of significant digits correct.
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Changes in Matter

9. Review Essential Questions Vocabulary
What is a physical change and what are several common examples?
What defines a chemical change? How can you recognize a chemical change?
How does the law of conservation of mass apply to chemical reactions?
Vocabulary
physical change
phase change
chemical change
law of conservation of mass
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Changes in Matter