Redox practice worksheet Name:
1.
In which which subs substa tanc ncee is the the oxida oxidati tion on numbe numberr of nitrogen zero? A.
2.
B.
N2
+
6
B.
+
2
0
In the the reacti action on Al + Cr reducing agent is A.
6.
NH3
C.
NO NO2
D.
4.
N2 O
Al0
B.
Cr3+
C.
3+
!
C.
4
D.
3
+
In the the reac reacti tion on 2K + Cl2 oxidized is A.
What What is the the oxid oxidat atio ion n numbe numberr of carbo carbon n in NaHCO3 ? A.
3.
Date:
5.
4
Cl2
B.
!
Cl Cl
2KCl, 2KCl, the species species
C.
K
D.
K+
As an S2 ion ion is oxidi oxidize zed d to an S0 atom, atom, the number of protons in its nucleus
A.
decreases
B.
C.
rema remain inss the the sam samee
increases
0
Al + Cr , the the
Al3+
D.
Cr0
Given Given the proba probable ble reacti reaction on for for the nick nickel-c el-cadmi admium um battery battery:: 2Ni(OH)3 + Cd ( + 2Ni(OH)2 + Cd(OH)2 Which species is oxidized during the discharge of the battery? A.
7.
8.
Ni2+
B.
C.
If ele eleme ment nt X form formss the oxi oxide dess XO XO and and X 2 O3 , the oxidation numbers of element X are A.
+
C.
+
1 and
+
1 and
+
2 3
B.
+
D.
+
2 and
+
2 and
+
10.
H2 O
B.
H2 O2
C.
OF2
0
B.
2
C.
+6
D.
Cd2+
In the equation Cu(s) + 2Ag+ (aq) ! Cu 2+ (aq) + 2Ag(s), the oxidizing agent is A.
Cu0
B.
Ag+
C.
Cu2+
D.
Ag0
4 11.
D.
D.
In the the reac reacti tion on Al + Cr3+ reducing agent is A.
IO I O2 12.
What What is is the oxi oxida dati tion on numb number er of sul sulfu furr in H 2 SO4 ? A.
Cd0
3
Oxyge Oxygen n has a positi positive ve oxid oxidati ation on numbe numberr in the compound A.
9.
Ni3+
+4
B.
Cr3+
C.
Al 3+ + Cr, the
Al3+
D.
Cr
In the the comp compou ound nd Na Na2 HPO4 , which element has a negative oxidation number? A.
page 1
Al
!
H
B.
O
C.
P
D.
Na
13.
Which species undergoes a loss of electrons? Mg(s) + 2Ag + (aq) A.
Mg(s)
C.
2+
Mg
!
17.
Mg 2+ (aq) + 2Ag(s) B.
(aq)
D.
+
2Br
C.
2Br + 2e
!
B.
Cl2
Br 2
D.
Cl2 + 2e
Br 2 + 2e
!
!
2Cl + 2e
!
Cl
Ag(s) Which half-reaction correctly represents reduction?
Given the reaction: 2Na + 2H2 O ! 2Na+ + 2OH + H 2
Which substance is oxidized? A.
15.
A.
Ag (aq)
18. 14.
In the reaction Cl2 + 2Br (aq) ! 2Cl (aq) + Br2 , which half-reaction correctly represents oxidation?
H2
B.
+
H
C.
Na
D.
+
Na
Which change occurs when an Sn2+ ion is oxidized?
19.
A.
S2 + 2e
B.
S2
C.
Mn7+ + 3e
D.
Mn7+
!
!
S 0
S 0 + 2e
!
!
Mn 4+
Mn 4+ + 3e
A solution contains 90 grams of a salt dissolved in 100 grams of water at 40 C. The solution could be an unsaturated solution of
A.
Two electrons are lost.
B.
Two electrons are gained.
A.
KCl
B.
KNO3
C.
Two protons are lost.
C.
NaCl
D.
NaNO3
D.
Two protons are gained. 20.
16.
21.
Which is an oxidation-reduction reaction?
A redox reaction always involves A.
4Na + O2
!
2Na2 O
A.
a change in oxidation number
B.
3O2
B.
a change in phase
C.
AgNO3 + NaCl ! AgCl + NaNO3
C.
the transfer of protons
D.
KI ! K + + I
D.
the formation of ions
!
2O 3
Which is a redox reaction? A.
CaCO3
C.
2NH4 Cl + Ca(OH)2
!
CaO + CO2 !
2NH 3 + 2H2 O + CaCl2
page 2
B.
NaOH + HCl ! NaCl + H2 O
D.
2H2 O
!
2H 2 + O2
Redox practice worksheet
22.
In the reaction
26.
3Cl2 + 6NaOH
!
Which equation represents the half-reaction that takes place at the fork?
5NaCl + NaClO3 + 3H2 O;
Cl2 undergoes
23.
A.
oxidation, only
B.
reduction, only
C.
both oxidation and reduction
A.
Ag+ + NO3
D.
neither oxidation nor reduction
B.
AgNO3
C.
Ag+ + e
D.
Ag(s) ! Ag+ + e
In the reaction AgNO3 (aq) + NaCl(aq) the reactants
!
NaNO3 (aq) + AgCl(s), 27.
A.
gain electrons, only
B.
lose electrons, only
C. D.
C.
Mg + 2e
!
Mg 2+
Mg ! Mg 2+ + 2e
B. D.
Cl2 + 2e Cl2
!
!
2Cl
2Cl + 2e
C.
!
Ag(s)
A.
Sn0 + 2e
C.
Li0 + e
!
!
Sn 2+
Li +
B.
Na0 + e
D.
Br2 0 + 2e
!
Na+
!
2Br
fusion transmutation
B. D.
Which half-cell reaction correctly represents oxidation? A.
Pb2+ + 2e
C.
Pb2+
!
Pb 2+
Pb
B.
Pb + 2e
D.
Pb ! Pb 2+ + 2e
!
!
Pb + 2e
The reaction that takes place in a chemical cell is best classied as A.
Ag+ + NO3
29. 25.
AgNO3
neither gain nor lose electrons
In the reaction Mg + Cl2 ! MgCl2 , the correct half-reaction for the oxidation that occurs is A.
!
Which half-reaction correctly represents a reduction reaction?
both gain and lose electrons
28. 24.
!
Which represents the positive electrode of a nickel-cadmium battery? A.
Ni(OH)3
B.
Cd
C.
Ni
D.
Cd(OH)2
redox cracking 30.
page 3
The diagram shown represents an electroplating arrangement. In the setup shown, an object to be plated with metal would be the A.
anode at
A
B.
anode at
B
C.
cathode at
A
D.
cathode at
B
Redox practice worksheet
31.
In this electrolytic cell, electrode as the
A is
designated
34.
35.
32.
A.
anode and is positive
B.
anode and is negative
C.
cathode and is positive
D.
cathode and is negative
Based on Reference Table N, what is the standard electrode potential (E 0 ) for the oxidation of Cu(s) to Cu2+ (aq) ? A.
+0.52 V
B.
+0.34 V
C.
0.52 V
D.
0.34 V
Which statement best describes the key?
The diagram shown represents a chemical cell at 298K and 1 atmosphere.
Which species represents the cathode? A.
33.
Zn
B.
Zn2+
C.
Cu
D.
Cu2+
Which part of the electroplating system is provided by the fork?
A.
the anode, which is the negative electrode
B.
the cathode, which is the negative electrode
C.
the anode, which is the positive electrode
D.
the cathode, which is the positive electrode
page 4
A.
It acts as the cathode and is negative.
B.
It acts as the cathode and is positive.
C.
It acts as the anode and is negative.
D.
It acts as the anode and is positive.
Redox practice worksheet
36.
The diagram below shows a key being plated with copper in an electrolytic cell.
38.
Given the reduction reaction for this cell: 2+
Cu
(aq) + 2e
!
Cu(s)
This reduction occurs at
37.
A.
A, which is the anode
B.
A, which is the cathode
C.
B, which is the anode
D.
B, which is the cathode
39.
Where does oxidation occur in an electrochemical cell? A.
at the cathode in both an electrolytic cell and a voltaic cell
B.
at the cathode in an electrolytic cell and at the anode in a voltaic cell
C.
at the anode in both an electrolytic cell and a voltaic cell
D.
at the anode in an electrolytic cell and at the cathode in a voltaic cell
Base your answer(s) to the following question(s) on the diagram and balanced equation below, which represent the electrolysis of molten NaCl.
Base your answer(s) to the following question(s) on the diagram below, which represents a voltaic cell at 298K and 1 atm.
When the switch is closed, which electrode will attract the sodium ions? 40.
Base your answer(s) to the following question(s) on the information and diagram below. The apparatus shown in the diagram consists of two inert platinum electrodes immersed in water. A small amount of an electrolyte, H 2 SO4 , must be added to the water for the reaction to take place. The electrodes are connected to a source that supplies electricity.
Describe the direction of electron ow between the electrodes when switch S is closed.
What particles are provided by the electrolyte that allow an electric current to ow?
page 5
Redox practice worksheet
41.
Base your answer(s) to the following question(s) on the diagram below. The diagram shows a voltaic cell with copper and aluminum electrodes immediately after the external circuit is completed.
43.
Base your answer(s) to the following question(s) on the information below. Underground iron pipes in contact with moist soil are likely to corrode. This corrosion can be prevented by applying the principles of electrochemistry. Connecting an iron pipe to a magnesium block with a wire creates an electrochemical cell. The magnesium block acts as the anode and the iron pipe acts as the cathode. A diagram of this system is shown below.
As this voltaic cell operates, the mass of the Al(s) electrode decreases. Explain, in terms of particles, why this decrease in mass occurs.
42.
Base your answer(s) to the following question(s) on the information below.
State the direction of the ow of electrons between the electrodes in this cell.
A ashlight can be powered by a rechargeable nickel-cadmium battery. In the battery, the anode is Cd(s) and the cathode is NiO2 (s). The unbalanced equation below represents the reaction that occurs as the battery produces electricity. When a nickel-cadmium battery is recharged, the reverse reaction occurs. Cd(s) + NiO2 (s) + H2 O(`)
!
44.
Base your answer(s) to the following question(s) on the information below. A voltaic cell with magnesium and copper electrodes is shown in the diagram below. The copper electrode has a mass of 15.0 grams.
Cd(OH)2 (s) + Ni(OH) 2 (s)
Determine the change in oxidation number for the element that makes up the anode in the reaction that produces electricity.
When the switch is closed, the reaction in the cell begins. The balanced ionic equation for the reaction in the cell is shown below the cell diagram. After several hours, the copper electrode is removed, rinsed with water, and dried. At this time, the mass of the copper electrode is greater than 15.0 grams. State the direction of electron ow through the wire between the electrodes when the switch is closed.
page 6
Redox practice worksheet
45.
Explain, in terms of copper ions and copper atoms, why the mass of the copper electrode increases as the cell operates. Your response must include information about both copper ions and copper atoms.
48.
When the redox equation Cr3+ (aq)+3Mn(s) ! Mn2+ (aq)+ Cr(s) is completely balanced, 3+ the coecient of Cr (aq) will be A.
46.
Base your answers to the following question(s) on the information below.
49.
The diagram below represents an operating electrolytic cell used to plate silver onto a nickel key. As the cell operates, oxidation occurs at the silver electrode and the mass of the silver electrode decreases.
50.
1
B.
2
C.
3
D.
4
Which redox equation is correctly balanced? A.
Cr3+ + Mg
B.
Al3+ + K
C.
Sn4+ + H 2
D.
Br2 + Hg ! Hg 2+ + 2Br
!
!
Cr + Mg2+
Al + K+
!
Sn + 2H+
Given the reaction: 2Al0 (s) + 3Ni2+ (aq) ! 2Al 3+ (aq) + 3Ni0 (s) What is the total number of moles of electrons lost by 2 moles of Al 0 (s)?
Identify the cathode in the cell. A. 47.
6
B.
2
C.
3
D.
8
When the redox equation Cr3+ (aq)+3Mn(s) ! Mn2+ (aq)+ Cr(s) is completely balanced, 3+ the coecient of Cr (aq) will be A.
1
B.
2
C.
3
D.
4
page 7
Redox practice worksheet
Problem-Attic format version 4.4.178 c 2011–2013 EducAide Software Licensed for use by Simone Shaker Terms of Use at www.problem-attic.com
Redox practice worksheet 1. Answer: 2. Answer:
05/09/2013
B
20. Answer:
A
D
21. Answer:
D
A
22. Answer:
C
C
23. Answer:
D
C
24. Answer:
C
6. Answer:
C
25. Answer:
B
7. Answer:
B
26. Answer:
B
8. Answer:
C
27. Answer:
D
9. Answer:
C
28. Answer:
D
10. Answer:
B
29. Answer:
A
11. Answer:
A
30. Answer:
D
B
31. Answer:
A
13. Answer:
A
32. Answer:
C
14. Answer:
D
33. Answer:
C
15. Answer:
A
34. Answer:
D
16. Answer:
A
35. Answer:
A
A
36. Answer:
B
18. Answer:
C
37. Answer:
19. Answer:
D
3. Answer: 4. Answer: 5. Answer:
12. Answer:
17. Answer:
38. Answer:
From the anode to cathode or half-cell 2 to half-cell 1. C
Teacher's Key 39. Answer: 40. Answer: 41. Answer:
42. Answer: 43. Answer:
44. Answer:
negative electrode, cathode, or one on the right ions, charged particles, H 3 O+ , SO4 2
Aluminum atoms are losing electrons and becoming aluminum ions that are entering the solution.
from 0 to +2 Acceptable answers but not limited to: Electrons ow from the magnesium block to the iron pipe. Electrons ow from the Mg to the Fe through the wire. Electrons ow from the anode to the cathode in a voltaic cell. from the block to the pipe
The electrons ow from the Mg electrode to the Cu electrode. from anode to cathode
45. Answer:
Copper ions from the solution are reduced to copper atoms at the electrode, increasing the mass of the electrode. Copper ions become copper atoms. The number of copper ions decreases, and the number of copper atoms increases.
46. Answer:
Ni(s) key key nickel
47. Answer:
B
48. Answer:
B
49. Answer:
D
50. Answer:
A
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