1. Chapter 19 Oxidation-Reduction Reactions Pg. 595 Oxidation- valence electrons are lost Reduction- valence electrons are gained Rules for determining the oxidation number of an element (pg. 595) Practice assigning Oxidation numbers (pg. 612 #7 a-j) (pg.612 #6)

2. Oxidation-Reduction Reaction Also called-Redox Transfer of electrons One cannot happen without the other. O xidation R eduction I s I s L osing G aining Oxidation #increases Oxidation # decreases

3. Remember:Oil Rig Determine Oxidation or Reduction (pg. 612 #4) Pg. 599 #3 a. is an example. Try b-e on your own for practice. Practice Pg. 605 #1 Pg. 612 #2 a-i,3,5 a-c,17 a-e,18

4. Hon Chem Ch 20 Pg 655 Electrochemical Cells AKA batteries Pg 643 Zn is good reducing agent (gets oxidized, loses electrons, ox# goes up) Cu is good oxidizing agent (gets reduced, gains electrons, ox# goes down)

5. Parts and Types of Batteries Pg 656-9 1. Zinc-Carbon Dry Cell a. big, used in flashlights, C and D batteries b. Zn container – anode, negative, becomes + as loses electron c. C rod in center – cathode, + bump on end of battery, becomes negative as gains electrons

6. 2. Alkaline Batteries a. smaller, AA and AAA, cameras, remotes b. Zn and KOH instead of Zn and C 3.Hg Batteries a. tiny, hearing aids, watches b. Zn, KOH, Steel, HgO

7. Corrosion and Prevention Pg 661-2 Fe is oxidized, loses electrons, forms rust Salt and acid speed up the oxidation Zn coating prevents oxidation due to Pg 643, called galvanizing Electric potential difference = volts (how hard electricity pushes thru wire)

8. Recharging Batteries Pg 667-9 Voltaic cell – battery making electricity, anode gives electrons to cathode Electrolytic cell – battery when being recharged, storing electricity, direct current source forces cathode to give electrons back to anode DC sources - wall charger with diode to change AC to DC, car alternator, other battery (jumping a car) Can be recharged as long as enough products to act as reactants to reverse reaction, corrosion is loss of products/reactants so can’t recharge after corroded Pg 669**do redox rxn for car battery