Chem equations

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

2. LecturePLUS Timberlake 2 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 )

3. LecturePLUS Timberlake 3 A Chemical Reaction Reactants Products

4. LecturePLUS Timberlake 4 Learning Check E2 A. How does an equation indicate a change in the identity of the reacting substances? B. How did the yellow and green reactants combine? C. Did all the reactants form product? Why or why not?

5. LecturePLUS Timberlake 5 Learning Check E2 A. How does an equation indicate a change in the identity of the reacting substances? The formulas of the reactants are different than the formulas of the products. B. How did the yellow and green reactants combine? 1 yellow combined with 1 green. C. Did all the reactants form product? Why or why not? No. There were more yellow reactants than green.

6. LecturePLUS Timberlake 6 Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction Reactants Products MgO + C CO + Mg magnesium oxide to form carbon monoxide reacts with carbon and magnesium

7. LecturePLUS Timberlake 7 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

8. LecturePLUS Timberlake 8 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 2 Al + 3 S Al 2 S 3 Balanced

9. LecturePLUS Timberlake 9 Matter Is Conserved H 2 + Cl 2 2 HCl + + Total atoms = Total atoms 2 H, 2 Cl 2H, 2 Cl

10. LecturePLUS Timberlake 10 Law of Conservation of Mass In any ordinary chemical reaction, matter is not created nor destroyed

11. LecturePLUS Timberlake 11 Balance Equations with Coefficients Coefficients in front of formulas balance each type of atom 4 NH 3 + 5 O 2 4 NO + 6 H 2 O 4 N = 4 N 12 H = 12 H 10 O = 10 O

12. LecturePLUS Timberlake 12 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

13. LecturePLUS Timberlake 13 Learning Check E4 Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 1) 2 2) 4 3) 8 B. Number of O atoms in 4 H 2 O 1) 2 2) 4 3) 8 C. Number of Fe atoms in Fe 3 O 4 1) 1 2) 3 3) 4

14. LecturePLUS Timberlake 14 Solution E4 Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 3) 8 B. Number of O atoms in 4 H 2 O 2) 4 C. Number of Fe atoms in Fe 3 O 4 2) 3

15. LecturePLUS Timberlake 15 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 1) 1, 3, 2 2) 3, 1, 2 3) 3, 1, 1 B. Al + Cl 2 AlCl 3 1) 3, 3, 2 2) 1, 3, 1 3) 2, 3, 2

16. LecturePLUS Timberlake 16 Learning Check E5 C. Fe 2 O 3 + C Fe + CO 2 1) 2, 3, 2,3 2) 2, 3, 4, 3 3) 1, 1, 2, 3 D. Al + FeO Fe + Al 2 O 3 1) 2, 3, 3, 1 2) 2, 1, 1, 1 3) 3, 3, 3, 1 E. Al + H 2 SO 4 Al 2 (SO 4 ) 3 + H 2 1) 3, 2, 1, 2 2) 2, 3, 1, 3 3) 2, 3, 2, 3

17. LecturePLUS Timberlake 17 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