1. Electrochemistry

2. OIL RIG Electrochemistry Oxidation is loss (of e-)
Reduction is gain (of e-)

3. LEO the lion goes GER Lose electrons = Oxidation
Gain electrons = Reduction

4. Balancing Acidic Reactions
Split the reaction into two halves
Balance the common element on the two sides.
Balance the Oxygen by adding water to the opposing side
Balance the hydrogen by adding H+ ions to the opposing side
Balance the overall charge by adding electrons

5. Redox Reactions in Acid
Al + MnO4-1  Al3+ + Mn2+

6. MnO4-1+ Fe2+  Fe3+ + Mn2+

7. Cr2O HNO2  Cr NO3-1

8. C + H+ + SO42-  CO2 + SO2

9. Basic Redox Calculate the charge of P in PO4-3
Calculate the charge of Cr in Cr2O7-2

10. Steps Split into two half reactions Balance the common ion
Balance the charge of the common ion by using electrons
Balance the overall charge by using OH-
Balance the hydrogen by adding H2O

11. Balancing Basic Redox Reactions
Break into two halves
Balance common element
Balance Oxygen by adding water to opposing side
Balance hydrogen by adding H+ ions to opposing side
Balance overall charge by adding electrons
Get rid of H+ by adding OH- to both sides (H + OH = H2O).
Cancel out waters from both sides.
Find least common multiple of electrons
Combine two halves.

12. Redox Reactions in Basic Solutions
Mg OCl-  Mg(OH) Cl-

13. Cl- + Cr2O7-2  Cr3+ + ClO2-

14. PbO2 + SeO32-  PbO + SeO42-

15. MnO4- + NH3  NO3- + MnO2

16. Electrochemistry Study of the flow of electrons Study of electricity
Powered by Redox reactions

17. OIL RIG Electrochemistry Oxidation is loss (of e-)
Reduction is gain (of e-)

18. LEO the lion goes GER Lose electrons = Oxidation
Gain electrons = Reduction

19. An Ox and a Red Cat Cathode – where reduction takes place (GER)
Red Cat (Reduction at the Cathode)
Anode – where oxidation takes place (LEO)
An Ox (Anode has Oxidation)

20. FAT CAT
Electrons travel From Anode To CAThode in a voltaic or electrolytic cell

21. Electrolytic Cells vs. Voltaic Cells
A cell which contains a nonspontaneous reaction caused by passing a current through the solution
Example: solution with wire connecting the two
Galvanic or Voltaic cells, are done by spontaneous reactions
Example: batteries

22. In one beaker, there is a solution of Iron (II) with an iron electrode immersed in the liquid. A second beaker contains a solution of Cadmium (II) with a cadmium electrode immersed into the liquid. The two beakers are connected by a salt bridge, and the following reaction takes place. Fe + Cd2+  Fe2+ + Cd

23. A solution of Cu2+ with a Cu electrode and a solution of Zn2+ with a Zn electrode. The Cu electrode is becoming bigger while the Zn electrode is becoming smaller.

24. A solution of sodium chloride and water has a current passed through it. As the current flows through the container, hydrogen gas begins to form on one electrode, while chlorine gas begins to form on the other.

25. Starter 4/28/14 1) Pick up a white board, eraser, and Expo
(***DO NOT WASTE THE EXPO DRAWING RANDOM THINGS***)
2) Get out homework of Electric Cells
3) KEEP HW on your desk but clear desk of everything else. All you need is:
Whiteboard
Expo
Eraser
HW: Electric Cells

26. Spontaneity of the Reaction
If E is positive the reaction is _____________
If E is negative the reaction is ____________

27. Cu + Zn2+  Cu2+ + Zn

28. Na+ + H2O  Na + O2

29. Electroplating
1 mole of e- = Coulombs
Amperes = Coulombs/sec

30. Remember
If solving for Amps, that is equal to Coulombs per second. Solve for Coulombs and then divide by the number of seconds

31. Calculate the mass of Copper metal produced during the passage of 12
Calculate the mass of Copper metal produced during the passage of 12.5 amperes through a solution of copper (II) sulfate for 30 minutes

32. What volume of Oxygen (at STP) is produced by the oxidation of water in electrolysis of copper (II) sulfate in the previous example.

33. Calculate the amount of time required to produce 2000 grams of magnesium metal by electrolysis of molten MgCl2 using a current of 75 A.

34. A Cr3+ solution is electrolyzed, using a current of 17. 60 A
A Cr3+ solution is electrolyzed, using a current of A. What mass of Cr is plated out after 1.50 days?

35. What amperage is required to plate out 24
What amperage is required to plate out 24.6 grams Cr from a Cr+3 solution in a period of 2.8 hours?