Electrochemistry Exam Practice Questions

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Electrochemistry Exam Practice

Questions

(2)

Red or Ox?

What has happened to the Pb after the reaction?

PbO + CO  Pb + CO2

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• What is the oxidation state of S in SF6?

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Balancing the following redox reaction: Fe 2+ + Cr

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Answer

Balancing the following redox reaction: Fe 2+ + Cr

2O72-  Fe3+ + Cr3+ (acidic conditions)

Oxidation: 6 x (Fe+2  Fe+3 + 1 e-)

Reduction: Cr2O72- + 14H+ + 6e-  2 Cr3+ + 7H 2O

6 Fe+2 + Cr

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Balance the following redox rxn under the following condition:

NO2- + Al

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Answer:

Balance the following redox rxn under the following condition:

NO2- + Al

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Balance the following redox rxn under the following condition:

NO3- + Zn

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Answer:

Balance the following redox rxn under the following condition:

NO3- + Zn

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Given the shorthand notation for an electrochemical cell

Au(s)/Fe(CN)64-(aq), Fe(CN)

63-(aq)//Ag(S2O3)23-(aq), S2O32-(aq)/Ag(s)

a) Draw a picture of the above electrochemical cell (label the anode and cathode).

b) Write oxidation and reduction half reactions for the two cell compartments.

(11)

Find the cell potential,

Cd(s)/Cd(NO3)2(aq)//KCl(aq)/AgCl(s)/Ag(s), if the right half cell contains 0.5 M KCl and the left half-cell contains 0.010 M Cd(NO3)2 (aq). (Need table of standard potentials).

Write the net cell reaction and state whether

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What is the change in the oxidation number of

chromium when K2Cr2O7 becomes CrCl3?

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Explain how to determine which substances

are oxidized and which are reduced in the following reaction.

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Matching

Match each item with the correct statement below.

a. anode d. half-cell

b. battery e. cathodec. fuel cell

1. the electrode at which oxidation occurs

2.one part of a voltaic cell in which either oxidation or reduction occurs

3.the electrode at which reduction occurs

4.a group of cells that are connected together

5.a voltaic cell in which a fuel substance undergoes

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Matching - ANSWERS

Ans

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Matching

Match each item with the correct statement below.

a. electrode d. voltaic cell

b.electrolysis e. dry cell c. salt bridge

1.a tube containing a conducting solution

2.a conductor in a circuit that carries electrons to or from a substance other than a metal

3.an electrochemical cell that is used to convert chemical energy to electrical energy

4.a voltaic cell in which the electrolyte is a paste

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Matching - ANSWERS

Ans

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Calculate the voltage of a cell composed of a

copper electrode in a copper(II) solution and an aluminum electrode in a solution with

aluminum ions.

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Balance in an acidic solution:

NO3- + Cu NO + Cu+2

Answer: 2 NO3- + 3 Cu + 8H+ 2 NO + 3 Cu+2 + 4 H

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Describe the similarities & differences

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Figure

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References

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