1. LecturePLUS Timberlake1 Chapter 5 Chemical Reactions and Quantities Chemical Changes Balancing Chemical Equations

2. LecturePLUS Timberlake2 Physical Properties color melting point boiling point electrical conductivity specific heat density state (solid, liquid, or gas)

3. LecturePLUS Timberlake3 Physical Change Changes in physical properties melting boiling condensation No change occurs in the identity of the substance Example: Ice, rain, and steam are all water

4. LecturePLUS Timberlake4 Chemical Change Atoms in the reactants are rearranged to form one or more different substances Old bonds are broken; new bonds form Examples: Fe and O 2 form rust (Fe 2 O 3 ) Ag and S form tarnish (Ag 2 S)

5. LecturePLUS Timberlake5 Learning Check E1 Classify each of the following as a 1) physical change or 2) chemical change A. ____ a burning candle B. ____ melting ice C. ____ toasting a marshmallow D. ____ cutting a pizza E. ____ boiling water

6. LecturePLUS Timberlake6 Solution E1 Classify each of the following as a 1) physical change or 2) chemical change A. __2__ a burning candle B. __1_ melting ice C. __2__ toasting a marshmallow D. __1__ cutting a pizza E. __1__ boiling water

7. LecturePLUS Timberlake7 Chemical Reaction A process in which at least one new substance is produced as a result of chemical change.

8. LecturePLUS Timberlake8 A Chemical Reaction Reactants Products

9. LecturePLUS Timberlake9 Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction ReactantsProducts MgO + CCO + Mg magnesium oxide to form carbon monoxide reacts with carbon and magnesium

10. LecturePLUS Timberlake10 Reading A Chemical Equation 4 NH 3 + 5 O 2 4 NO + 6 H 2 O Four molecules of NH 3 react with five molecules O 2 to produce four molecules NO and six molecules of H 2 O or Four moles NH 3 react with 5 moles O 2 to produce four moles NO and six moles H 2 O

11. LecturePLUS Timberlake11 A Balanced Chemical Equation Same numbers of each type of atom on each side of the equation Al + S Al 2 S 3 Not Balanced 2Al + 3S Al 2 S 3 Balanced

12. LecturePLUS Timberlake12 Matter Is Conserved H 2 + Cl 2 2 HCl ++ Total atoms=Total atoms 2 H, 2 Cl2H, 2 Cl Total Mass=Total Mass 2(1.0) + 2(35.5)2(36.5) 73.0 g=73.0 g http://www.saskschools.ca/curr_content/chem30/swf/hydrogenequil.swf

13. LecturePLUS Timberlake13 Law of Conservation of Mass In any ordinary chemical reaction, matter is not created nor destroyed

14. LecturePLUS Timberlake14 Balance Equations with Coefficients Coefficients in front of formulas balance each type of atom 4NH 3 + 5O 2 4NO + 6H 2 O 4 N = 4 N 12 H=12 H 10 O=10 O

15. 15 Steps in Balancing An Equation Fe 3 O 4 + H 2 Fe + H 2 O Fe: Fe 3 O 4 + H 2 3 Fe + H 2 O O:Fe 3 O 4 + H 2 3 Fe + 4 H 2 O H: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O

16. LecturePLUS Timberlake16 Learning Check E5 Balance each equation. The coefficients for each equation are read from left to right A. Mg + N 2 Mg 3 N 2 B. Al + Cl 2 AlCl 3

17. LecturePLUS Timberlake17 Learning Check E5 C. Fe 2 O 3 + C Fe + CO 2 D. Al + FeO Fe + Al 2 O 3 E. Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2

18. LecturePLUS Timberlake18 Solution E5 A. 3 Mg +N 2 Mg 3 N 2 B. 2 Al + 3 Cl 2 2 AlCl 3 C. 2 Fe 2 O 3 + 3 C 4 Fe + 3 CO 2 D. 2 Al + 3 FeO 3 Fe + Al 2 O 3 E. 2 Al + 3 H 2 SO 4 Al 2 (SO 4 ) 3 + 3 H 2