2. Warm Up Predict the products and balance the following equations: a.KI + Br 2 → b.H 2 SO 4 + KOH →

3. Questions on Activity Series WS?

4. Questions on Word Equations WS?

5. Genie in a Bottle H 2 O 2 +

6. Honors Electrochemistry

7. Electron Transfer Reactions  Electron transfer reactions are oxidation-reduction or redox reactions.  Result in the generation of an electric current (electricity) or be caused by imposing an electric current.  This field of chemistry is often called ELECTROCHEMISTRY.

8. Redox Vocab  OXIDATION—loss of electron(s) by a species; increase in oxidation number; increase in oxygen.  REDUCTION—gain of electron(s); decrease in oxidation number; decrease in oxygen; increase in hydrogen.  OXIDIZING AGENT—electron acceptor; species is reduced.  REDUCING AGENT—electron donor; species is oxidized.  OXIDATION—loss of electron(s) by a species; increase in oxidation number; increase in oxygen.  REDUCTION—gain of electron(s); decrease in oxidation number; decrease in oxygen; increase in hydrogen.  OXIDIZING AGENT—electron acceptor; species is reduced.  REDUCING AGENT—electron donor; species is oxidized.

9. You can’t have one… without the other!  Reduction (gaining electrons) can’t happen without an oxidation to provide the electrons.  You can’t have 2 oxidations or 2 reductions in the same equation. Reduction has to occur at the cost of oxidation LEO the lion says GER! GER!

10. Another way to remember  OIL RIG

11. OXIDATION-REDUCTION REACTIONS Direct Redox Reaction Oxidizing and reducing agents in direct contact. Cu(s) + 2 Ag + (aq) Cu 2+ (aq) + 2 Ag(s) Cu(s) + 2 Ag + (aq) → Cu 2+ (aq) + 2 Ag(s)

12. OXIDATION-REDUCTION REACTIONS Indirect Redox Reaction A battery functions by transferring electrons through an external wire from the reducing agent to the oxidizing agent.

13. AnodeCathode Basic Concepts of Electrochemical Cells

14.  To obtain a useful current, we separate the oxidizing and reducing agents so that electron transfer occurs thru an external wire. CHEMICAL CHANGE ---> ELECTRIC CURRENT This is accomplished in a GALVANIC or VOLTAIC cell. A group of such cells is called a battery. http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/galvan5.swf

15. Electrons travel thru external wire. Electrons travel thru external wire.  Salt bridge allows anions and cations to move between electrode compartments. Electrons travel thru external wire. Electrons travel thru external wire.  Salt bridge allows anions and cations to move between electrode compartments. Zn --> Zn 2+ + 2e- Cu 2+ + 2e- --> Cu <--AnionsCations--> OxidationAnodeNegativeOxidationAnodeNegative Reduction Cathode Positive Reduction Cathode Positive RED CAT

16. Oxidized or Reduced?  Oxidation number is assigned to an element in a molecule based on the distribution of electrons in the molecule.

17. Rules for assigning oxidation numbers. The oxidation number of…. 1.Any pure element is 0 2.Monatomic ion = the charge on the ion 3.More EN element in a binary compound = the number equal to the charge it would have if it were an ion. 4.F = 1- 5.O = 2- unless combined with F or is a peroxide 6.H = 1+, unless combined with a metal (1-) 7.Sum of the oxidation numbers in a neutral atom = 0. 8.Polyatomic ion = charge of polyatomic ion

18. Let’s Practice NaOH H 2 SO 3 KNO 3 SO 2 CaCl 2

19. How can you tell? The atoms or ions of an element experience an increase in oxidation state…oxidation. Na 0 → Na 1+ + 1e - The atoms or ions of an element experience a decrease in oxidation state… reduced. Cl 2 + 2e - → 2Cl l-

20. Half-Reaction Represents the part of the reaction undergoing oxidation/reduction. Cu → Cu 2+ + 2e - 2NO 3 + 2e - + 4H + → 2NO 2 + 2H 2 O

21. Not all reactions are Redox SO 2 + H 2 O → H 2 SO 4

22. Let’s look at the WS…

23. Warm Up- How did you do on the redox WS? Na= +1 O= -2 Cr=+6 K= +1O= -2 O = -2C= +4 H= +1C = -4 O= -2H= +1Cl= +7 O = -2Mn = +4

24. Electrochemical Cell Lab- Everyone fills in their own lab sheets… turn in recorders Leader/Recorder- Keeps everyone on task, makes sure instructions are being followed carefully. Aides scientist. Reader- Reads every single word out loud… helps others make sense of lab. Scientist- Obtains materials and follows all instructions. Helps others make sense of the lab.

25. Read the Introduction Paragraph as a whole group. Quickly obtain the materials and goggles… get started on this guided inquiry lab. Make sure all names are on the recorders paper… turn in when complete.