Electrochemistry

Multiple Choice Questions Electrochemistry:

Questions 1 through 5 refer to the following cell: A galvanic cell is constructed in which one half cell consists of an Ag electrode in a 1 M AgNO₃ solution and the other half cell is a standard hydrogen electrode. The net cell reaction and standard cell voltage are: H₂ + 2Ag⁺ = 2H⁺ + 2Ag E⁰= 0.80 V

1	The anode reaction is: Ag⁺+ e^- = Ag 2H⁺ + 2e^-= H₂ Ag = Ag⁺ + e^- H₂ = 2H⁺ + 2e^- Ag⁺ = Ag²⁺ + e^-

2	The standard reduction potential for the Ag/Ag⁺ couple is: 0.80 V-0.80 V0.40 V-0.40 V1.60 V

3	In solution, positive ions move towards: the hydrogen electrode. the silver electrode. both electrodes. neither electrode. not possible to decide.

4	Which of the following would cause the cell voltage to increase. addition of NaCl to the Ag/Ag⁺ half cell. addition of NaCl to the H₂/H⁺ half cell. addition of Na₂S to the Ag/Ag⁺ half cell. addition of Na₂S to the H₂/H⁺ half cell. none of the above.

5	If the solution in the standard hydrogen electrode were replaced by pure water, what would the cell voltage be? Hint: [H₃O⁺] = 1.0 x 10^-7 M. 0.00 V0.39 V0.80 V0.95 V1.21 V
Use the following information to answer questions 6 -9. A galvanic cell is constructed using a strip of nickel metal immersed in a 1 M nickel chloride solution connected by a salt bridge to a strip of zinc metal immersed in a 1 M zinc chloride solution. The standard reduction potential for Ni⁺² is -0.25 V and for Zn⁺² is -0.76 V at 298 K.
6	The standard cell potential for this reaction is _____ V. 1.01-1.01-0.510.510.99

7	The cathode reaction (reduction) for this cell is: Ni⁺² + 2e^- ® Ni Zn⁺² + 2e^- ® Zn Zn ® Zn⁺² + 2e^- Ni ® Ni⁺² + 2e^- Zn⁺² + Ni ® Ni⁺² + Zn

8	Which ions migrate toward the anode? Ni⁺²Zn⁺²both (A) and (B) Cl^-both (B) and (D)

9	If the nickel chloride concentration is reduced to 1.0 x 10-5 with the zinc chloride concentration remaining at 1 M, the cell voltage will be _____ V. 0.660.19-0.36-0.660.36

10	In a galvanic cell _____ migrate towards the _____ compartment. cations, anode anions, cathode cations, cathode positive ions, anode negative ions, cathode
Question 11 through 15 are based on a galvanic cell, prepared by immersing a strip of nickel metal into aqueous 1 M NiSO₄ and a strip of silver metal into aqueous 1 M AgNO₃. The two solutions are separated by a porous barrier. The DE° of the cell is 1.05 volts. The standard reduction potential of the Ni²⁺/Ni is -0.25 volts Electrons flow from the nickel electrode through the external circuit (i.e. wire) to the silver electrode.
11	The standard reduction potential of the Ag/Ag⁺ is: +1.30 volts-0.80 volts+0.25 volts-0.25 volts+0.80 volts

12	The anode reaction is: Ag = Ag⁺ + e^- Ag⁺ + e^- = Ag Ni = Ni²⁺ + 2e^- Ni²⁺ + 2e^- = Ni Ni + 2Ag⁺ = Ni²⁺ + 2Ag

13	The above cell is altered by changing the concentration of Ag⁺ to 0.100 M, everything else remaining the same. The cell voltage would change from 1.05 volts to: 0.93 volts 0.99 volts 0.81 volts 1.02 volts No Change

14	Calculate the equilibrium constant (K_c) of the spontaneous reaction taking place in the above Galvanic Cell. 35.6 1.05 5.7 x 10¹⁵ 3.1 x 10³⁵ 6.3 x 10¹⁷
Use the following information to answer questions 15 through 18. Given the following standard reduction potentials: Ag⁺/Ag E° = 0.80 V Cu²⁺/Cu E° = 0.34 V Consider a standard cell in which the following reaction occurs spontaneously: Cu(s) + 2Ag⁺ ==> Cu²⁺ + 2Ag(s)
15	The anode reaction is: Cu(s) ® Cu²⁺ + 2e^- 2Ag⁺ + 2e^- ® 2Ag(s) Cu²⁺ + 2e^- ® Cu(s) 2Ag(s) ® 2Ag⁺ + 2e^- Cu(s) + 2Ag⁺ ® Cu²⁺ + 2Ag(s)

16	The standard cell voltage is: 1.14 V-0.46 V0.46 V-1.26 V1.26 V

17	In the external circuit the electrons flow from the ______ electrode to the ______ electrode. Cu, CuCu, Ag Ag, CuAg, Ag

18	If the [Ag⁺] was decreased to 1.00 x 10^-6M, while the [Cu²⁺] remains at 1.0 M, the cell voltage would _______ by _______ volts. increase, 0.35 decrease, 0.35 increase, 0.18 decrease, 0.18 increase, 0.12
Question 19 through 21 are based on a galvanic cell, prepared by immersing a strip of copper metal into aqueous 1 M CuSO₄ and a strip of silver metal into aqueous 1 M AgNO₃. The two solutions are separated by a porous barrier. The metal strips are connected by a conducting wire. The DE° of the cell is 0.46 volts at 25°C. The standard reduction potential of the Cu\|Cu²⁺ is +0.34 volts Electrons flow from the copper electrode through the external circuit (i.e. wire) to the silver electrode.
19	The standard reduction potential of the Ag\|Ag⁺ is: +1.30 volts-0.80 volts+0.25 volts-0.25 volts+0.80 volts

20	The cathode reaction is: Ag = Ag⁺ + e^- Ag⁺ + e^- = Ag Cu = Cu²⁺ + 2e^- Cu²⁺ + 2e^- = Cu Cu + 2Ag⁺ = Cu²⁺ + 2Ag

21	The above cell is altered by changing the concentration of Ag⁺ to 0.0100 M, everything else remaining the same. The cell voltage would change from 0.46 volts to: 0.40 volts0.58 volts0.34 volts0.50 voltsNo Change