Download Chap19-20StudyGuide09 ans

Chemistry - Chap 19-20 Study Guide
1.What is the most common oxidation number of combined oxygen?
Rule
a. –2
c. 0
b. –1
d. +1
2.The algebraic sum of the oxidation numbers of the atoms in a compound
Rule
a. is always zero.
c. is always –1.
b. is always +1.
d. can be any whole number.
3.What are the oxidation numbers in the compound KCl?
Follow Rules
a. K = 0, Cl = 0
c. K = +1, Cl = –1
b. K = –1, Cl = +1
d. K = +2, Cl = –2
4.What are the oxidation numbers in the ion SO32–?
Follow Rules
a. S = +6, O = –2
c. S = +4, O = –2
b. S = +1, O = –1
d. S = 0, O = –1
5.In an oxidation, atoms or ions
Definition
a. increase their oxidation number.
b. decrease their oxidation number.
c. do not change their oxidation number.
d. have a zero oxidation number after the reaction.
6. In a reduction, atoms or ions
Definition
a. increase their oxidation number.
b. decrease their oxidation number.
c. do not change their oxidation number.
d. have a zero oxidation number after the reaction.
Def by a bunch of ways
7. In the reaction O2 + 4e– → 2 O–2, the species O2 is
a. oxidized.
c. electrolyzed.
b. reduced.
d. autooxidized.
8. In the reaction 2K + Br2 → 2K+ + 2Br–, which species is reduced?
Gain e- :get smaller charge
a. K only
c. both K and Br2
b. Br2 only
d. neither K nor Br2
9. Which of the following is an oxidation-reduction reaction?
H to +1 Cl to -1
a. H2 → 2H+
b. 2O– → O22–
c. H2 + Cl2 → 2HCl
d. HCl + NaBr → HBr + NaCl
10. In a redox reaction, MnO4– is changed to Mn2+. How many electrons must be lost or gained by Mn?
+5 to +2
a. two lost
c. five lost
b. two gained
d. five gained
11. How does the number of electrons lost in an oxidation compare with the number gained in the simultaneous reduction?
a. The two numbers are always equal.
Rule
b. The number lost is always greater than the number gained.
c. The number lost is always less than the number gained.
d. No relationship exists between the two numbers.
12.
During redox reactions, oxidizing agents
ox ag cause loss they gain
a. increase their oxidation number.
c. keep the same oxidation number.
b. decrease their oxidation number.
d. do not participate.
13.
During redox reactions, reducing agents
see 12
a. increase their oxidation number.
c. keep the same oxidation number.
b. decrease their oxidation number.
d. do not participate.
14.
In redox reactions,
see 12,13
a. the oxidizing agent is the substance oxidized.
b. the reducing agent is the substance oxidized.
c. both oxidizing and reducing agents are oxidized.
d. the reducing agent is the substance reduced.
15.
In redox reactions,
see above
a. the oxidizing agent is the substance reduced.
b. the reducing agent is the substance reduced.
c. the oxidizing agent is the substance oxidized.
d. both oxidizing and reducing agents are on the same side of the chemical equation.
16. Which is the most active reducing agent among the elements?
Best giver (likes to lose)
a. cesium
c. fluorine
b. iodine
d. lithium
17. Which is the most active oxidizing agent among the elements?
Opposite of #16
a. cesium
c. fluorine
b. iodine
d. lithium
18. In which system does a spontaneous redox reaction produce electrical energy?
def
a. electrochemical cell
c. electroplating cell
b. electrolytic cell
d. half-cell
19. Where does oxidation take place in an electrochemical cell?
Anox redcat
a. the anode
c. the anode or the cathode
b. the cathode
d. the half-cell
20. In which cell does a current drive a nonspontaneous redox reaction?
def
a. electrolytic cell
c. electrochemical cell
b. dry cell
d. voltaic cell
21. Electrons in a voltaic cell normally flow
a to c
a. from cathode to anode.
b. through a porous barrier.
c. in both directions through the external circuit.
d. from anode to cathode.
22. For electricity to flow in a voltaic cell, the two half-cells must be
rule
a. connected by a wire and a porous barrier.
c. in the same solution.
b. completely isolated from one another.
d. connected to a dry cell.
23. Which process deposits metal onto a surface?
memory
a. electrolysis
c. autooxidation
b. electroplating
d. oxidation
24. In an electroplating cell, the object to be plated is the
memory
a. external circuit.
c. anode.
b. electrolyte.
d. cathode.
25. A dry cell battery is:
memory
a. a voltaic cell
c. an electrolytic cell
b. either voltaic or electrolytic
d. non-spontaneous
26. A lead-acid battery:
memory
a. is a voltaic cell when used to start the engine c. is an electrolytic cell when being charged
b. is a reversible REDOX reaction
d. all of the above
27. Hydrogen and oxygen reaction in a REDOX reaction to produce electricity in:
memory
a. an electrolytic cell
c. a lead acid battery
b. a fuel cell
d. a dry cell
Determine the oxidation number of each underlined atom in the following
28. C2H3O2-1
29. KNO3 30. Cr2O7-2
31. KMnO4
32. Al2O3
33. K2SO3
0
+5
+6
+7
+3
+4
Use a Standard Reduction Table to prove whether the following reaction is spontaneous or nonspontaneous. Determine the positive
or negative potential for each reaction.
+2
34.
Ni + Cu
+2
-
+ Cu
→Ni
+/59 = spont
35.
-
Cl + Br → Cl + Br
2
2
Balance each of the following. Provide the half reactions and the oxidizing and reducing agents.
+2
-2
36. 2e- + H2O + 2Cu → Cu O +2H+
+2
-2
. 2H2O + 2Cu + HPO
Ox agent
3
H2O + HPO
2
-3
→ Cu O
2
+
PO
-2
-2
H SO + MnO → SO
3
-3
→ +
PO
4
+ 3H+ + 2e-
+ 5H+
red agent
37. H2O + H2SO3 + → SO4 + 4H+ + 2e2
4
3
2
red agent Ox agent
4
+2
+ Mn + H2O
+2
2e- + 4H++ MnO → + Mn
2
+ 2H2O
-.29=non
38. Au Au+3 + 3e4H++ 3e- + NO3- 2H2O + NO
+
4H + Au + NO3 Au+3 + NO + 2H2O
red agent Ox agent
39. C2H2 +4H2O 2 CO2 + 10H++ 10e-
5e- + 8H+ + MnO4- + Mn+2
+ 4H2O
6H++ C2H2 + 2 MnO4- 2CO2 + 2Mn+2 + 4H2O
Calculate the potential in volts for each of the following spontaneous reactions. Also determine the: a)anode b) cathode
c) direction of electron flow (i.e., for each reaction where do the electrons start from and where do they end up) d) oxidizing agent e)
reducing agent f) the overall balanced reaction
40. Cr(s) + Ni2+(aq) Ni(s) + Cr2+(aq) Eo = -.25-(-.41) = 0.16v a) anode = Cr
b) cath=Ni
c)Cr to Ni
d)Ni+2
2+
2+
e)Cr
f) 2Cr(s) + 3 Ni (aq) 3 Ni(s) + 2 Cr (aq)
o
41. Al(s) + H+(aq) Al3+(aq) + H2(g)
E = 1.66 +0 = 1.66v a) anode =Al
+
3+
f) . 2 Al(s) + 6H (aq) 2 Al (aq) + 3H2(g)
b) cath=Pt
c)Al to H2
o
42. Fe2+(aq) + MnO4-(aq) Fe3+(aq) + Mn2+(aq)
b) cath=Pt
E = 1.51 +.77 = 2.28v a) anode =Pt
2+
+
2+
d) MnO4
e) Fe
f) 8H + 5Fe (aq) + MnO4-(aq) 5 Fe3+(aq) + Mn2+ +4H2O(aq)
d)H+1
e)Al
c) Fe+2 to MnO4-