ELECTROCHEMICAL CELLS 4-26-12NAME ROW PD

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A) It is spontaneous and requires an electric current.B) It is spontaneous and produces an electric current.C) It is non-spontaneous and produces an electric current.D) It is non-spontaneous and requires an electric

current.

(1) Which statement describes the redox reaction that occurswhen an object is electroplated?

Base your answers to questions 2 and 3 on the diagram belowwhich represents the electroplating of a metal fork with Ag(s).

A) Ag+ + e– ® Ag(s)B) Ag+ + NO3– ® AgNO3

C) AgNO3 ® Ag+ + NO3–

D) Ag(s) ® Ag+ + e–

(2) Which equation represents the half-reaction that takes placeat the fork?

A) the anode, which is the negative electrodeB) the cathode, which is the positive electrodeC) the cathode, which is the negative electrodeD) the anode, which is the positive electrode

(3) Which part of the electroplating system is provided by thefork?

A) Cu2+ + 2e– ® Cu0 B) Zn2+ + 2e– ® Zn0

C) Cu0 – 2e– ® Cu2+ D) Zn0 – 2e– ® Zn2+

(4) A standard zinc half-cell is connected to a standard copperhalf cell by means of a wire and a salt bridge. Whichelectronic equation represents the oxidation reaction thattakes place?

A) electroplating B) electrochemicalC) electromagnetic D) electrolytic

(5) A battery consists of which type of cells?

The diagram below shows the electrolysis of fused KCl.

A) Positive ions migrate toward the anode, where theylose electrons.

B) Positive ions migrate toward the cathode, where theylose electrons.

C) Positive ions migrate toward the cathode, wherethey gain electrons.

D) Positive ions migrate toward the anode, where theygain electrons.

(6) What occurs when the switch is closed?

A) neither electrolytic cells nor voltaic cellsB) both electrolytic cells and voltaic cellsC) electrolytic cells, onlyD) voltaic cells, only

(7) Reduction occurs at the cathode in

A) electrical energy to chemical energyB) thermal energy to nuclear energyC) chemical energy to electrical energyD) nuclear energy to thermal energy

(8) Which energy conversion occurs in an operating electrolyticcell?

A) only oxidation occursB) only reduction occursC) both oxidation and reduction occurD) neither oxidation nor reduction occurs

(9) In a chemical cell, electrical energy will be produced when

A) neither oxidation nor reduction occursB) energy is required for the reaction to occurC) energy is produced when the reaction occursD) both oxidation and reduction occur

(10) A voltaic cell differs from an electrolytic cell in that in avoltaic cell

ELECTROCHEMICAL CELLS

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A) It produces electrical energy.B) It undergoes a spontaneous redox reaction.C) It uses radioactive nuclides.D) It requires an external energy source.

(11) Which statement describes one characteristic of anoperating electrolytic cell?

Base your answer to the following question on the diagram belowwhich represents a chemical cell at 298 K and 1 atmosphere.

A) Cu2+ B) Zn C) Zn2+ D) Cu

(12) Which species represents the cathode?

A) electrolysis B) saponificationC) distillation D) polymerization

(13) Which procedure requires the use of an external electriccurrent to force a redox reaction to occur?

A student collects the materials and equipment below to construct avoltaic cell:

• two 250-mL beakers• wire and a switch• one strip of magnesium• one strip of copper• 125 mL of 0.20 M Mg(NO3)2(aq)• 125 mL of 0.20 M Cu(NO3)2(aq)

A) an anode B) a batteryC) a cathode D) a salt bridge

(14) Which additional item is required for the construction ofthe voltaic cell?

The diagram below shows a key being plated with copper in anelectrolytic cell

A) B, which is the anodeB) A, which is the cathodeC) B, which is the cathodeD) A, which is the anode

(15) Given the reduction reaction for this cell:

Cu2+(aq) + 2e- ® Cu(s)

This reduction occurs at

Base your answer to the following question on the diagram belowof an electrolytic cell in which the electrodes are tin and copper.

A) A will dissolve and B will become coated withcopper.

B) A will dissolve and B will become coated with tin.C) B will dissolve and A will become coated with copper.D) B will dissolve and A will become coated with tin.

(16) When the switch is closed, what will happen to the twoelectrodes?

A) electrical energy to chemical energyB) electrical energy to nuclear energyC) chemical energy to electrical energyD) nuclear energy to electrical energy

(17) A voltaic cell spontaneously converts

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A) Pb2+(aq) and Pb(s)B) Ni(s) and Pb(s)C) Pb2+(aq) and Ni2+(aq)D) Ni(s) and Ni2+(aq)

(18) Given the redox reaction in an electrochemical cell:

Ni(s) + Pb2+(aq) « Ni2+(aq) + Pb(s)

A salt bridge is used to connect

A) positive electrode, where oxidation occursB) negative electrode, where reduction occursC) negative electrode, where oxidation occursD) positive electrode, where reduction occurs

(19) In an electrolytic cell, the anode is always the

A) The cell reaction has reached equilibrium.B) The concentration of the products has decreased.C) The concentration of the reactants has increased.D) The cell reaction has completely stopped.

(20) What is indicated when a chemical cell's voltage (E0) hasdropped to zero?

A) Oxidation and reduction both occur at the cathode.B) Oxidation occurs at the anode, and reduction

occurs at the cathode.C) Oxidation occurs at the cathode, and reduction occurs

at the anode.D) Oxidation and reduction both occur at the anode.

(21) Which statement describes where the oxidation andreduction half-reactions occur in an operatingelectrochemical cell?

A diagram of a chemical cell and an equation are shown below.

A) the Pb(s) to the Cu(s)B) the Cu2+(aq) to the Cu(s)C) the Pb2+(aq) to the Pb(s)D) the Cu(s) to the Pb(s)

(22) When the switch is closed, electrons will flow from

Base your answer to the following question on the informationbelow.

Electroplating is an electrolytic process used to coat metalobjects with a more expensive and less reactive metal. Thediagram below shows an electroplating cell that includes abattery connected to a silver bar and a metal spoon. The barand spoon are submerged in AgNO3(aq).

(23) Explain the purpose of the battery in this cell.

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Base your answers to questions 24 and 25 on the information below.

The diagram and balanced ionic equation below represent a voltaic cell with copper andsilver electrodes and the reaction that occurs when the cell is operating.

(24) Describe the direction of electron flow in the externalcircuit in this operating cell.

(25) State the purpose of the salt bridge in this voltaic cell.

(26) What is the oxidation number of nitrogen in NO(g)?

(27) Explain, in terms of activity, why HCl(aq) reacts withZn(s), but HCl(aq) does not react with Cu(s).

Answer KeyELECTROCHEMICAL CELLS

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(1) D

(2) A

(3) C

(4) D

(5) B

(6) C

(7) B

(8) A

(9) C

(10) C

(11) D

(12) D

(13) A

(14) D

(15) B

(16) B

(17) C

(18) C

(19) A

(20) A

(21) B

(22) A

(23) Examples: – Thebattery provides theelectrical energynecessary for thereaction to occur.

(24) Acceptable responsesinclude, but are notlimited to: • Electronsflow from the copperelectrode to the silverelectrode through thewires and voltmeter. •The e- flow is from Cuto Ag in the externalcircuit from anode tocathode

(25) Acceptable responsesinclude, but are notlimited to: • The saltbridge allows for themigration of ionsbetween the half-cells.• The salt bridgeprevents polarizationof the half-cellsmaintains electricalneutrality

(26) +2(27) Acceptable responses

include, but are notlimited to: • Zinc ismore active thanhydrogen, but copperis less active thanhydrogen. • On Table J, Zn is above H2, andCu is below H2.