CHEMISTRY TEST FOR RSBI XII FIRST SEMESTER

Students, I want to help you learning back the concepts that you have learnt during this semester. Please test yourself by using the following item tests. These are about colligative properties, balancing redox reaction and electrochemical cells.

1. A solution is prepared from 50.0 g of solid sucrose, C12H22O11 in 250 g of water at 25.0oC. The vapor pressure of pure water is 23.8 torr at 25oC. What is the vapor pressure of the solution? (Ar C = 12, H = 1, O = 16).
a. 22.8
b. 23.0
c. 23.3
d. 23.6
e. 23.8
2. A solution consists of 5,85 grams of table salt, NaCl (Mr = 58,5) in 800 g of water. This solution boils at the same temperature with a solution which contains of 3 g X (a non electrolyte substance) in 200 g of water. Mr of X is ….
a. 40
b. 50
c. 60
d. 80
e. 120
3. A solution prepared by dissolving x grams of nicotine (a non electrolyte) in water to make a 12 mL of solution has an osmotic pressure of 7,55 atm at 250C. The mass of nicotine is …. (Mr nicotine = 160; R = 0,082 L atm/K mol)
a. 0,20
b. 0,60
c. 0,80
d. 1,40
e. 2,80
4. Which of the following solutes will produce the highest solution boiling point when dissolved in water?
a. 1,5 moles of MgCl2
b. 2 moles of methanol
c. 3 moles of NaCl
d. 4,5 moles of urea
e. 5 moles of ethanol
5. After balancing the redox reactions below, the value of a, b, c, d, and e in order are ….
aK2C2O4 + bK2Cr2O7 + cH2SO4 à dCO2 + Cr2(SO4)3 + K2SO4 + eH2O
a. 3, 1, 7, 3, 7
b. 3, 1, 7, 6, 7
c. 3, 2, 7, 3, 7
d. 6, 2, 7, 6, 7
e. 6, 1, 7, 3, 7
6. In an electrochemical cell of Zn – Cu, what occurs when the circuit is closed?
a. Zn(s) --> Zn2+(aq) + 2e
b. Cu(s) --> Cu2+(aq) + 2e
c. 2H2O(l) --> 2H2(g) + O2(g)
d. Electrons flow from Cu to Zn.
e. Electric current flows from Zn to Cu
7. From the following listed standard electrode potentials, the biggest Eo for the cell is ….
Mg2+(aq) + 2e --> Mg(s) Eo = --2,24 V
Sn2+(aq) + 2e --> Sn(s) Eo = --0,14 V
Hg2+(aq) + 2e --> Hg(s) Eo = +0,62 V
Cu2+(aq) + 2e --> Cu(s) Eo = +0,34 V
a. Sn(s)+Hg2+(aq) --> Sn2+(aq)+Hg(s)
b. Sn(s)+Cu2+(aq) --> Sn2+(aq)+Cu(s)
c. Hg(s)+Cu2+(aq) --> Hg2+(aq)+Cu(s)
d. Mg(s)+Cu2+(aq) --> Mg2+(aq)+Cu(s)
e. Mg(s)+Hg2+(aq) --> Mg2+(aq)+Hg(s)
8. Na2SO4(aq) is electrolysed by using graphyte as electrodes. The reaction that is occured at the positive electrode is ....
a. Na(s) --> Na+(aq) + e
b. Na+(aq) + e --> Na(s)
c. 2H+(aq) + 2e --> H2(g)
d. 2H2O(l) + 2e --> H2 + 2OH-(g)
e. 2H2O(l) --> 4H+(aq) +O2(g) +4e
9. How many hours will it take to plate out 4,85 g of Cr from a Cr2(SO4)3 solution using a current of 1.50 A? (Ar Cr = 52)
a. 5
b. 4,8
c. 3
d. 2,4
e. 1,2
10. Draw the Zn - Cu cell and electrolysis cell, then explain the comparison of these two electrochemical cells.

ELECTROCHEMICAL CELL PROBLEMS

This picture is a voltaic cell or we can call a Daniell cell. When the circuit is closed, the bulb lights brightly. Please explain clearly about this cell. After that, explain again for other cells, if the electrodes are changed with the following :

1. Cu - Fe

2. Mg - Fe

3. Ag - Zn

4. Fe - Sn

5. Ag - Cu

OK students, firstly you can think in a global manner, it's no problem. However, after that, you have to write down step by step clearly. A note is realy very important for you. To day you feel that you understand all the above problems. Unfortunately, if you don't think in dept and completely, latter perhaps you will find nothing in your mind about these concepts. So my suggestion is please do carefully everything you have to do, to develop your knowledge gradually.

A VOLTAIC CELL

When you go to the chemistry laboratory and you want to work with electrochemical cells, firstly do the voltaic cell of Zn - Cu.

A voltaic cell is a spontaneous reaction, so that you have to seperate the solution into two half-cells, the first part is oxidation and the other is reduction.


Prepare all the apparatus needed and arrange them as the above picture. For a Zn-Cu cell, please dip a zinc rod in ZnSO4(aq) and a Cu rod in CuSO4(aq). Do not dip Zn rod in CuSO4(aq), because they will react. Connect the Zn rod to the copper rod by using a wire. You can use a galvanometer and a plug key.

The two aqueous solutions in the beackers, ZnSO4 and CuSO4 are interlinked one of another through a salt bridge which is an inverted 'u' tube which is filled with saturated semi solid paste of Agar-agar saturated in NaCl, KCl or KNO3 solution (Agar-agar is a carbohydrate which forms a jelly like substance when dissolved in hot water). You can use filter paper, wet with NaCl(aq). It is more simple than the first.

When the circuit is completed, a deflection is observed in the (G) towards the zinc electrode indicating that the electrons are flowing from the Zn electrode to Cu electrode. The Zn electrode will oxidize.

The electrons lost by the Zn metal and move through electrode and reach the Cu electrode at which they are accepted by Cu2+ ions of the solution to form neutral copper atoms.

In an electrochemical cell, each electrode constitutes one half of the cell and the reaction taking place at the electrode is called half-cell reaction. The overall cell reaction is obtained by adding the two half-cell reactions.

When Zn is added to CuSO4(aq), Zn directly displaces Cu2+(aq) from CuSO4(aq). However, in the electrochemical cell there is no direct contact between Zn and CuSO4(aq). Here, the elecrons can flow from Zn rod to Cu. So the chemical energy changes to the electrical energy. Hence the electrochemical cell acts as a source of electrical current although for a short interval.

The electrode at which oxidation takes place, the metal rod becomes negative charged is called negative electrode. The electrode at which reduction takes place, the metal rod becomes positive charged is called positive electrode.

Accordingly, in the above electrochemical cell, Zn electrode acts as negative electrode while Cu electrode acts as positive.

The function of salt bridge:
a) acts as a link between the two aqueous solution
b) overcomes liquid junction potential.
c) maintains the electrical neutrality of the aqueous solution of the electrodes by releasing or sending oppositely charged ions into the solution.

The cell notation of Zn - Cu is written as : Zn(s)/Zn2+(aq)//C reu2+(aq)/Cu(s) or Zn(s)/ZnSO4(aq)//CuSO4(aq)/Cu(s).

The chemical equation is :
(Anode) Oxidation : Zn(s) --> Zn2+ + 2e Eo = 0,76 volt
(Cathode) Reduction : Cu2+ + 2e --> Cu(s) Eo = 0,34 volt
Redox Reaction : Zn(s)+Cu2+(aq) --> Zn2+(aq)+Cu(s) Eo cell = 1,10 volt

Sometimes you can directly caculate the Eo cell without write down the chemical equation.
Eo cell = Eo Cu2+/Cu - Eo Zn/Zn2+ (Eo of Red at Cathode - Eo of Ox at Anode)
Eo cell = 0,34 volt - . -0,76 volt = 1,10 volt.

THE ANSWER OF VOLTAIC CELL QUIZ Part II

1.The equation that represents a reaction that is not a redox reaction is ….
1. Zn + CuSO4 → ZnSO4 + Cu
2. 2H2O2 → 2H2O + O2
3. H2O + CO2 → H2CO3
4. 2H2 + O2 → 2H2O
Answer (Reaction no. 3)
2.For the galvanic cell described below, the correct line notation is ….
Cl2 + 2e- → 2Cl- (E0 = 1.36v)
Cu+ + e- → Cu (E0 = 0.52v)
Answer : Pt(s)Cu(s)Cu+(aq)Cl2(g)2Cl-(aq)Pt(s)
3.What is indicated when a chemical cell's voltage (E) has dropped to zero?
Answer : The cell reaction has reached equilibrium.
4.Given the redox reaction:
2 Cr(s) + 3 Cu2+(aq) --> 2 Cr3+(aq) + 3 Cu(s)
Which reaction occurs at the cathode in an electrochemical cell?
Answer : reduction of Cu2+(aq)
5.Given the cell reaction:
2 H2O(l) --> 2 H2(g) + O2(g)
The cell is best described as ....
Answer : an electrolytic cell in which an endothermic reaction occurs
6.In an electrochemical cell, what is the purpose of the salt bridge?
Answer : It permits the migration of ions between the half-cells.
7.In a voltaic cell what type of ions move toward the cathode?
Answer : anions
8.What is the equation for the net cell reaction for the electrochemical cell:
Pb(s) PbI2(s) HI(aq) H2(g) Pt(s)
Answer : Pb(s) + 2HI(aq) --> PbI2(s) + H2
9.Referring to the table of Standard Cell Potentials below, determine the standard cell potential for the following reaction running in this direction:
2 Fe3+(aq) + Zn(s) --> 2 Fe2+(s) + Zn2+(aq)
Answer (+1.53 V)

STANDARD REDUCTION POTENTIALS E°(volts)
F2 + 2 e- ---> 2 F- Eo = +2.87 V
Au+ + e- ---> Au Eo = +1.69 V
Ag+ + e- ---> Ag Eo = +0.80 V
Fe3+ + e- ---> Fe2+ Eo = +0.77 V
Cu2+ + 2 e- ---> Cu Eo = +0.34 V
2 H+ + 2 e- ---> H2 Eo = 0 V
Pb2+ + 2 e- ---> Pb Eo = -0.13 V
Fe2+ + 2 e- ---> Fe Eo = -0.44 V
Zn2+ + 2 e- ---> Zn Eo = -0.76 V
Na+ + e- ---> Na Eo = -2.71 V
Li+ + e- ---> Li Eo = -3.05 V
10.Which of the following metal ions in aqueous solution is most easily oxidized to its aqueous ionic form?
Answer (Na)
11.Which metal is used as a coating on steel to limit corrosion?
Answer (Zn)
12.Given the nickel-cadmium battery reaction:
2 NiOOH + Cd + 2 H2O --> 2 Ni(OH)2 + Cd(OH)2
What occurs during discharge in the nickel-cadmium battery?
Answer : Ni3+ is reduced to Ni2+.
13.Referring to the table of standard cell potentials attached, determine the standard cell potential of the following reaction for the corrosion of iron in an acidic environment:
Fe(s) + 2 H+(aq) +1/2 O2(g) --> Fe2+(aq) + H2O(l)
Answer (Eo = +0.44 V)
14.Which ion in solution is most easily reduced to its elemental form?
Cu2+
15.In the alkaline energy cell the overall reaction is: Zn(s) + 2MnO2(s) + 2H2O ---> Zn(OH)2(s) + 2MnO(OH)(s). Which of the following half-reactions is taking place at the cathode?
2MnO2(s) +2 H2O + 2e- ---> 2MnO(OH)(s) + 2OH-(aq)
16.In the lead storage battery the product of both the cathode and anode reactions is?
Answer (PbSO4)
17.The fuel cell we discussed in class forms the following product:
Answer (H2O)
18.In an alkaline energy cell the overall cell reaction is as follows:
Zn(s) + 2 MnO2(s) + 2 H2O --> Zn(OH)2(s) + 2 MnO(OH)
Which of the following reactions is taking place at the cathode?
Answer : Zn(OH)2(s) + 2e- --> Zn(s) + 2 OH-(aq)
19.In a Nickel-Cadmium cell the following overall reaction is taking place:
Cd(s) + NiO2(s) + 2 H2O --> Cd(OH)2(s) + Ni(OH)3(s)
Which of the following half-reactions are taking place at the anode?
Answer : Cd(s) + 2 OH-(aq) --> Cd(OH)2(s) + 2e-

THE ANSWER OF VOLTAIC CELL QUIZ Part I

1.If the two half-cells below were combined, what would be the correct chemical equation to represent the spontaneous REDOX process?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : Cu2+ + H2 ==> 2H+ + Cu
2.If the two half-cells below were combined, what would be the voltage generated by the spontaneous REDOX process?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer (+0.34V)
3.If the two half-cells below were combined, which cell would undergo reduction?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : Copper half-cell
4.If the two half-cells below were combined, what would be the expected products of the spontaneous chemical reaction?
Zn2+ + 2e- <====> Zn (-0.76V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : H2 and Zn2+
5.Which of the following statements is FALSE?
Answer : Metal can be used for salt bridge
6.The following REDOX reactions all have positive Ecell voltages.
Cl2 + 2Br- ==> Br2 + 2Cl-
Br2 + 2I- ==> I2 + 2Br-
Cl2 + 2I- ==> I2 + 2Cl-
Which is the correct order of strength of oxidizing agent, from weakest to strongest?
Answer : Iodine < Bromine < Chlorine
7.The standard reduction potential for Zn2+ + 2e- ==> Zn, is -0.76 V, and the standard reduction potential for Fe3+ + e- ==> Fe2+, is +0.77V. What is the Ecell for the reaction below?
2Fe3+ + Zn ==> Zn2+ + 2Fe2+
Answer (+1.53)
8.Iron rusts when it comes into contact with water and oxygen. The change that the iron undergoes can be summarized thus; Fe ==> Fe2+ + 2e-. When iron metal is coated with solid zinc in a process called galvanizing, the oxidation of iron is prevented even if the zinc coating does not completely cover the iron metal. Which of the following statements serves best to explain these observations?
Answer : Solid zinc metal is more easily oxidized than iron
9.In the spontaneous reduction of Copper (II) ions with Nickel metal to form Copper metal and Nickel (II) ions, what will happen to the Ecell value when the concentration of Copper (II) ions is increased?
Cu2+ + 2e- <====> Cu (+0.34V)
Ni2+ + 2e- <====> Ni (-0.25V)
Answer : Ecell will increase
10.If the two half-cells below were combined, into which cell do anions from the salt bridge flow?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : Hydrogen
11.What value of Ecell do you expect for Pb(s) → Pb2+ + 2e-
in 0.015 M Pb2+ solution? E0 = +0.13 V
Answer (E = 0.00V)
12.Reduction potential is ....
Answer : an intensive property
13.The standard hydrogen electrode is assigned a potential of ….
Answer : zero volts
14.Calculate the value of E0cell for a galvanic cell that contains the following half cells:
Cl2 + 2e- → 2Cl- (E0 = 1.36v)
Cu+ + e- → Cu (E0 = 0.52v)
Answer (E0cell = 0.84 volts)
15.In all electrochemical cells, the process that takes place at the anode is … and the process that takes place at the cathode is ….
Answer : oxidation, reduction

VOLTAIC CELL QUIZ Part II

1.The equation that represents a reaction that is not a redox reaction is ….
1. Zn + CuSO4 → ZnSO4 + Cu
2. 2H2O2 → 2H2O + O2
3. H2O + CO2 → H2CO3
4. 2H2 + O2 → 2H2O
a.Reaction 1
b.Reaction 2
c.Reaction 3
d.Reaction 4
e.All of these are redox reactions
2.For the galvanic cell described below, the correct line notation is ….
Cl2 + 2e- → 2Cl- (E0 = 1.36v)
Cu+ + e- → Cu (E0 = 0.52v)
a.Pt(s)|Cl2(g)|2Cl-(aq)||Cu(s)|Cu+(aq)
b.Pt(s)|Cu(s)|Cu+(aq)||Cl2(g)|2Cl-(aq)|Pt(s)
c.Cu(s)|Cu+(aq)||Cl2(g)|2Cl-(aq)
d.Pt(s)|Cl2(g)|2Cl-(aq)||Cu(s)|Cu+(aq)|Pt(s)
e.Cu(s)|Cu+(aq)||Cl2(g)|2Cl-(aq)|Pt(s)
3.What is indicated when a chemical cell's voltage (E) has dropped to zero?
a) The concentration of the reactants has increased.
b) The concentration of the products has decreased.
c) The cell reaction has reached equilibrium.
d) The cell reaction has completely stopped.
4.Given the redox reaction:
2 Cr(s) + 3 Cu2+(aq) --> 2 Cr3+(aq) + 3 Cu(s)
Which reaction occurs at the cathode in an electrochemical cell?
a) reduction of Cu2+(aq)
b) reduction of Cu(s)
c) oxidation of Cr3+(aq)
d) oxidation of Cr(s)
5.Given the cell reaction:
2 H2O(l)  2 H2(g) + O2(g)
The cell is best described as
a) an electrolytic cell in which an exothermic reaction occurs
b) an electrolytic cell in which an endothermic reaction occurs
c) a galvanic cell in which an exothermic reaction occurs
d) a galvanic cell in which an endothermic reaction occurs
6.In an electrochemical cell, what is the purpose of the salt bridge?
a) It is the anode.
b) It is the cathode.
c) It permits the migration of ions between the half-cells.
d) It permits the mixing of solutions between the half-cells.
7.In a voltaic cell what type of ions move toward the cathode?
a. anions
b. cations
c. neither cations nor anions
d. freons
e. both cations and anions
8.What is the equation for the net cell reaction for the electrochemical cell:
Pb(s) | PbI2(s) | HI(aq) | H2(g) | Pt(s)
a. Pb(s) + 2I-(aq) --> PbI2(s) + 2e-
b. 2H+(aq) + 2e- --> H2(g)
c. Pb(s) + 2HI(aq) --> PbI2(s) + H2
d. both a and b
e. none of the above
9.Referring to the table of Standard Cell Potentials below, determine the standard cell potential for the following reaction running in this direction:
2 Fe3+(aq) + Zn(s) --> 2 Fe2+(s) + Zn2+(aq)
a) -2.30 V
b) +0.01 V
c) +0.78 V
d) +1.53 V
e) +2.30 V
STANDARD REDUCTION POTENTIALS E°(volts)
F2 + 2 e- ---> 2 F- E0 = +2.87
Au+ + e- ---> Au Eo = +1.69
Ag+ + e- ---> Ag Eo = +0.80
Fe3+ + e- ---> Fe2+ Eo = +0.77
Cu2+ + 2 e- ---> Cu Eo = +0.34
2 H+ + 2 e- ---> H2 Eo = 0
Pb2+ + 2 e- ---> Pb Eo = -0.13
Fe2+ + 2 e- ---> Fe Eo = -0.44
Zn2+ + 2 e- ---> Zn Eo = -0.76
Na+ + e- ---> Na Eo = -2.71
Li+ + e- ---> Li Eo = -3.05
10.Which of the following metal ions in aqueous solution is most easily oxidized to its aqueous ionic form?
a) Na
b) Pb
c) Zn
d) Ag
11.Which metal is used as a coating on steel to limit corrosion?
a) Na
b) Ca
c) K
d) Zn
12.Given the nickel-cadmium battery reaction:
2 NiOOH + Cd + 2 H2O --> 2 Ni(OH)2 + Cd(OH)2
What occurs during discharge in the nickel-cadmium battery?
a) Ni3+ is reduced to Ni2+.
b) Ni2+ is reduced to Ni3+.
c) Ni3+ is oxidized to Ni2+.
d) Ni2+ is oxidized to Ni3+.
13.Referring to the table of standard cell potentials attached, determine the standard cell potential of the following reaction for the corrosion of iron in an acidic environment:
Fe(s) + 2 H+(aq) +1/2 O2(g) --> Fe2+(aq) + H2O(l)
a) +0.44 V
b) +0.79 V
c) -0.79 V
d) +1.23 V
e) +1.67 V
14.Which ion in solution is most easily reduced to its elemental form?
a) Na+
b) Cu2+
c) Mg2+
d) Zn2+
15.In the alkaline energy cell the overall reaction is: Zn(s) + 2MnO2 (s) +2 H2O ---> Zn(OH)2(s) + 2MnO(OH) (s). Which of the following half-reactions is taking place at the cathode?
a) Zn2+(aq) + 2e- ---> Zn(s)
b) Zn(s) ---> Zn2+(aq) + 2e-
c) Zn(s) + 2OH-(aq)  Zn(OH)2(s) + 2e-
d) 2 MnO2(s) +2 H2O + 2e- ---> 2MnO(OH)(s) + 2OH- (aq)
16.In the lead storage battery the product of both the cathode and anode reactions is?
a) PbSO4
b) PbO2
c) Pb
d) H2SO4
17.The fuel cell we discussed in class forms the following product:
a) H2
b) H2SO4
c) H2O
d) H2S
e) O2
18.In an alkaline energy cell the overall cell reaction is as follows:
Zn(s) + 2 MnO2(s) + 2 H2O --> Zn(OH)2(s) + 2 MnO(OH)
Which of the following reactions is taking place at the cathode?
a) 2 MnO2(s) + 2 H2O + 2e- --> Zn(OH)2(s) + 2 MnO(OH)(s)
b) 2 MnO2(s) + 2 H2O + 2e- --> 2 MnO(OH)(s) + 2 OH-
c) Zn(s) + 2 OH-(aq) --> Zn(OH)2(s) + 2e-
d) Zn(OH)2(s) + 2e-  Zn(s) + 2 OH-(aq)
19.In a Nickel-Cadmium cell the following overall reaction is taking place:
Cd(s) + NiO2(s) + 2 H2O Cd(OH)2(s) + Ni(OH)3(s)
Which of the following half-reactions are taking place at the anode?
a) NiO2(s) + 2 H2O + 2e- --> Ni(OH)2(s) + 2 OH-
b) Cd(s) + 2 OH-(aq) --> Cd(OH)2(s) + 2e-
c) Cd(OH)2(s) + 2e- --> Cd(s) + 2 OH-(aq)
d) Ni(OH)2(s) + 2 OH- --> NiO2(s) + 2 H2O + 2e-

VOLTAIC CELL QUIZ Part I

1.If the two half-cells below were combined, what would be the correct chemical equation to represent the spontaneous REDOX process?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
(A) Cu2+ + H+ ==> 1/2 H2 + Cu
(B) Cu2+ + 2H+ ==> H2 + Cu
(C) Cu2+ + 1/2 H2 ==> H+ + Cu
(D) Cu2+ + H2 ==> 2H+ + Cu
(E) Cu + 2H+ ==> H2 + Cu2+
2.If the two half-cells below were combined, what would be the voltage generated by the spontaneous REDOX process?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
(A) +0.34V
(B) -0.34V
(C) 0.00V
(D) +0.68V
(E) -0.68V
3.If the two half-cells below were combined, which cell would undergo reduction?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
(A) Hydrogen half-cell
(B) Neither
(C) Both
(D) Copper half-cell
(E) Not enough information to tell
4.If the two half-cells below were combined, what would be the expected products of the spontaneous chemical reaction?
Zn2+ + 2e- <====> Zn (-0.76V)
H+ + e- <====> 1/2 H2 (0.00V)
(A) H+ and Zn2+
(B) H+ and Zn
(C) Zn and H2
(D) H2 and Zn2+
(E) None of the above
5.Which of the following statements is FALSE?
(A) Oxidation involves a loss of electrons
(B) Reduction involves a gain of electrons
(C) In the cell, electric current flows from a positive pole
(D) A spontaneous REDOX reaction has a positive Ecell voltage
(E) Metal can be used for salt bridge
6.The following REDOX reactions all have positive Ecell voltages.
Cl2 + 2Br- ==> Br2 + 2Cl-
Br2 + 2I- ==> I2 + 2Br-
Cl2 + 2I- ==> I2 + 2Cl-
Which is the correct order of strength of oxidizing agent, from weakest to strongest?
(A) Chlorine < Iodine < Bromine
(B) Bromine < Chlorine < Iodine
(C) Iodine < Bromine < Chlorine
(D) Chlorine < Bromine < Iodine
(E) Iodine < Chlorine < Bromine
7.The standard reduction potential for Zn2+ + 2e- ==> Zn, is -0.76 V, and the standard reduction potential for Fe3+ + e- ==> Fe2+, is +0.77V. What is the Ecell for the reaction below?
2Fe3+ + Zn ==> Zn2+ + 2Fe2+
(A) +2.30V
(B) +1.53V
(C) -2.30V
(D) -1.53V
(E) -0.75V
8.Iron rusts when it comes into contact with water and oxygen. The change that the iron undergoes can be summarized thus; Fe ==> Fe2+ + 2e-. When iron metal is coated with solid zinc in a process called galvanizing, the oxidation of iron is prevented even if the zinc coating does not completely cover the iron metal. Which of the following statements serves best to explain these observations?
(A) Solid zinc metal is more easily reduced than iron
(B) Solid zinc metal is more easily oxidized than iron
(C) Zinc ions are more easily reduced than iron
(D) Zinc ions are more easily oxidized than iron
(E) Solid zinc metal is more easily reduced than iron (II) ions
9.In the spontaneous reduction of Copper (II) ions with Nickel metal to form Copper metal and Nickel (II) ions, what will happen to the Ecell value when the concentration of Copper (II) ions is increased?
Cu2+ + 2e- <====> Cu (+0.34V)
Ni2+ + 2e- <====> Ni (-0.25V)
(A) Ecell will increase
(B) Ecell will decrease
(C) Ecell will be unchanged
(D) Not enough information to tell
(E) None of the above
10.If the two half-cells below were combined, into which cell do anions from the salt bridge flow?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
(A) Hydrogen
(B) Copper
(C) Neither
(D) Cannot tell from the information given
(E) None of the above
11.What value of Ecell do you expect for
Pb(s) → Pb2+ + 2e-
in 0.015 M Pb2+ solution? E0 = +0.13 V
a.E = +0.27V
b.E = +0.83V
c.E = +0.13V
d.E = 0.00V
e.E = +0.18V
12.Reduction potential is:
a. measured in amperes
b. an intensive property
c. an extensive property
d. always positive
13.The standard hydrogen electrode is assigned a potential of ….
a.0.76 volts
b.-1.00 volts
c.1.00 volts
d.zero volts
e.mines volts
14.Calculate the value of E0cell for a galvanic cell that contains the following half cells:
Cl2 + 2e- → 2Cl- (E0 = 1.36v)
Cu+ + e- → Cu (E0 = 0.52v)
a.E0cell = 0.84 volts
b.E0cell = 1.88 volts
c.E0cell = 0.32 volts
d.E0cell = -0.32 volts
e.E0cell = -0.84 volts
15.In all electrochemical cells, the process that takes place at the anode is … and the process that takes place at the cathode is ….
a.reduction, oxidation
b.oxidation, oxidation
c.reduction, reduction
d.oxidation, reduction