Determine the oxidation state for the element indicated in the following compounds or ions.
1. Al2(SO4)3
2. CrO4-2
3. In the reaction Fe2O3 + 3CO --> 2Fe + 3CO2. What is the oxidizing agent?
4. Define oxidation
5. Given the reaction; Mg + 2 HCl ---> MgCl2 + H2. What is reduced?
6. In the reaction 2 KClO3 ---> 2KCl + 3 O2
(a) oxygen loses 2 electrons (b) potassium loses 1 electron...(c) chlorine gains 6 electrons (d) oxygen is reduced
7. When a metal reacts to form a metallic ion it has been (a) oxidized (b) reduced (c) decomposed
Questions 8-10 refer to the following equation;
As2O3 + NO3- ----> H3AsO4 + NO
Write the half reactions for the above reaction.
8.____________________________________________________
9.___________________________________________________
Write the balanced equation
10.___________________________________________________
11. Calculate the cell potential for the following cell at 25°c
Ag+(0.1M)|Ag|| Mg|Mg+2(0.0001M)
12. Calculate D G for the following standard cell Br2|Br-||Cr|Cr+3
13. Gold is electroplated from Au(NO3)3. If a 5.00 amp current passes through the solution for 10.0 minutes, how many grams of gold will be plated?
Questions 14-19
A galvonic cell is made by placing a Cu electrode and 1M Cu+2 into a beaker. A silver electrode is placed into another beaker containing 1M Ag+. The two beakers are connected by a salt bridge.
14. Write the Oxidation half reaction that takes place.
15. Write the Reduction half reaction that takes place.
16. What product is formed at the negative electrode in the cell?
17. Which electrode is the anode?
18. What is the EMF for the cell?
19. What will happen to the voltage if the Ag+ concentration is lowered??
An electrolytic cell is made which contains a solution of 1M MgBr2
20. What is produced at the negative electrode?
21. What is produced at the positive electrode?
22. Which electrode is the anode?
23. What are the electrodes of typical dry cell battery made out of?
24. What is the formula for then electrolyte in a lead acid battery?
25. Write out the two half reactions for the lead acid battery.
26. Calculate the E°, DG and K for the lead acid battery
27 What is plated onto "galvanized nails to prevent them from rusting?
Answers:
1) +6
2) +6
3) Fe2O3
4) loss of electrons
5) HCl , (H+)
6) C
7) A
8)
9)
10)
11) 3.23V
12) -1054Kj/mol
13) 2.04g
14) Cu --> Cu+2 + 2e
15) Ag+ + 1e --> Ag
16) Cu+2
17) Cu
18) 0.46V
19) the voltage will go down
20) H2
21) Br2
22) Br2
23) Zn, MnO2
24)H2SO4
25) E = 2.04V, G= -394kJ/mol, K= 8.3x10 68
26) zinc