1. 1 Chapter 7 Chemical Reactions 7.1 Chemical Reactions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

2. 2 Physical Change In a physical change, The identity and composition of the substance do not change. The state can change or the material can be torn into smaller pieces. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

3. 3 Chemical Change In a chemical change, Reacting substances form new substances with different compositions and properties. A chemical reaction takes place. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

4. 4 Some Examples of Chemical and Physical Changes Table 7.1 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

5. 5 Classify each of the following as a 1) physical change or 2) chemical change A. ____Burning a candle. B. ____Ice melting on the street. C. ____Toasting a marshmallow. D. ____Cutting a pizza. E. ____Polishing a silver bowl. Learning Check

6. 6 Classify each of the following as a 1) physical change or 2) chemical change A. 2 Burning a candle. B. 1 Ice melting on the street. C. 2 Toasting a marshmallow. D. 1 Cutting a pizza. E. 2 Polishing a silver bowl. Solution

7. 7 Chemical Reaction In a chemical reaction A chemical change produces one or more new substances. There is a change in the composition of one or more substances. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

8. 8 Chemical Reaction In a chemical reaction, Old bonds are broken and new bonds are formed. Atoms in the reactants are rearranged to form one or more different substances. Fe and O 2 form rust (Fe 2 O 3 ). Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

9. 9 Evidence of a Chemical Reaction Physical changes that can be seen are evidence of a chemical reaction. Table 7.2 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

10. 10 Learning Check Identify the visible evidence of a chemical reaction in each of the following: 1. Methane gas in an outdoor heater burns with a blue flame. 2. Bleach removes stains from a shirt. 3. Bubbles of CO 2 are released when baking soda is mixed with vinegar.

11. 11 Solution Identify the visible evidence of a chemical reaction in each of the following: 1. Methane gas in an outdoor heater burns with a blue flame. Heat and a flame 2. Bleach removes stains from a shirt. Color change (color removed) 3. Bubbles of CO 2 are released when baking soda is mixed with vinegar. Formation of a gas (bubbles)