1. EXAM #2 MOVED TO FRIDAY, 10/16 Announcements

2. What is the oxidation number of Cl in NaOCl? 1. +5 2. +4 3. +3 4. +2 5. +1 6. 0 7. -1 8. -2 9. -3

4. Recognizing Redox Reactions Metals reacting with Nonmetals: 2 Al + 3 Br 2  Al 2 Br 6 Almost anything with Oxygen: 2 Mg + O 2  2 MgO S + O 2  SO 2 Organic Compounds: CH 4 + 2 O 2  CO 2 + H 2 O Others, more difficult to detect: 5 Fe 2+ + MnO 4 - + 8 H +  5 Fe 3+ + Mn 2+ + 4 H 2 O

5. Examples 4 Al(s) + 3 O 2 (g)  2 Al 2 O 3 (s) CuO(s) + H 2 (g)  Cu(s) + H 2 O( )

6. Examples CaCO 3 (s)  CaO(s) + CO 2 (g) MnO 4 - (aq) + 5 Fe 2+ (aq) + 8 H + (aq)  Mn 2+ (aq) + 4 H 2 O( ) + 5 Fe 3+ (aq)

7. Examples 2 H 2 O 2 (aq)  2 H 2 O( ) + O 2 (g) CaCO 3 (s) + 2 H + (aq)  CO 2 (g) + H 2 O( ) + Ca 2+ (aq)

8. Cool Redox Demo Vitamin C is an antioxidant  I 2 binds to starch  black  ascorbic acid + I 2  2 I - + dehydroascorbic acid

9. Types of Reactions Combination(Synthesis)DecompositionDisplacement # reactants > # products# reactants < # products# reactants = # products (usually) Spontaneous Heat Electrolysis Catalyst Single Double: Precipitation Double:Acid-Base Gas forming Redox

10. Cool Redox Redux Elephant Toothpaste I - (aq) 2H 2 O 2 (aq) → 2H 2 O(g) + O 2 (g) + Energy