1. Unit 5: Chemical Reactions
Section 1: Describing Reactions
Chemical Reaction
Law of Conservation of Mass
Chemical Equations and Balancing

2. A. Physical and Chemical Changes
During a physical change, some properties of a material change, but the composition of the material does not change.
Examples of physical changes:
Grinding
Cutting
Folding
Cracking
Filing
Bending
Phase changes (melting, boiling, condensing, etc)

3. A. Physical and Chemical changes
A change that involves one or more substances turning into new substances is called a chemical change.
Examples of chemical changes:
decomposing
rusting
exploding
burning
oxidizing
tarnishing
fermenting

4. PA. Physical and Chemical Changesand Chemical Changes
A magnet separates iron from sulfur. This is an example of a physical change.
A mixture of iron filings and sulfur can be changed. a) A magnet separates the iron from the sulfur. b) Heat combines iron and sulfur in a compound. Classifying Which change is a chemical change? Explain.

5. PhA. Physical and Chemical Changesand al and Chemical Changes
A mixture of iron and sulfur is heated. The iron and sulfur react and form iron sulfide. This is an example of a chemical change.
A mixture of iron filings and sulfur can be changed. a) A magnet separates the iron from the sulfur. b) Heat combines iron and sulfur in a compound. Classifying Which change is a chemical change? Explain.

6. B. Chemical Reaction
Chemical Change: new & different substances formed.
4 Evidences of Chemical Reaction:
energy transfer
(hot or cool)
color change
gas formed
precipitate formed
(solid)

7. A+B AB B. Chemical Reaction REACTANTS PRODUCTS
Chemical Equation:
A+B AB
yields
REACTANTS
PRODUCTS
present at the start of the rxn
produced in the rxn at the end