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General Chemistry Principles, Patterns, and Applications, 2011

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C O N C E PTUAL P R OBLEMS<br />

1. Is a hydrogen electrode chemically inert? What is the major disadvantage to using a hydrogen electrode?<br />

2. List two factors that affect the measured potential of an electrochemical cell <strong>and</strong> explain their impact on the<br />

measurements.<br />

3. What is the relationship between electron flow <strong>and</strong> the potential energy of valence electrons? If the valence<br />

electrons of substance A have a higher potential energy than those of substance B, what is the direction of<br />

electron flow between them in a galvanic cell?<br />

4. If the components of a galvanic cell include aluminum <strong>and</strong> bromine, what is the predicted direction of<br />

electron flow? Why?<br />

5. Write a cell diagram representing a cell that contains the Ni/Ni 2+ couple in one compartment <strong>and</strong> the SHE in<br />

the other compartment. What are the values of E° cathode ,E° anode , <strong>and</strong> E° cell ?<br />

6. Explain why E° values are independent of the stoichiometric coefficients in the corresponding half-reaction.<br />

7. Identify the oxidants <strong>and</strong> the reductants in each redox reaction.<br />

a. Cr(s) + Ni 2+ (aq) → Cr 2+ (aq) + Ni(s)<br />

b. Cl 2 (g) + Sn 2+ (aq) → 2Cl − (aq) + Sn 4+ (aq)<br />

c. H 3 AsO 4 (aq) + 8H + (aq) + 4Zn(s) → AsH 3 (g) + 4H 2 O(l) + 4Zn 2+ (aq)<br />

d. 2NO 2 (g) + 2OH − (aq) → NO − 2 (aq) + NO − 3 (aq) + H 2 O(l)<br />

8. Identify the oxidants <strong>and</strong> the reductants in each redox reaction.<br />

a. Br 2 (l) + 2I − (aq) → 2Br − (aq) + I 2 (s)<br />

b. Cu 2+ (aq) + 2Ag(s) → Cu(s) + 2Ag + (aq)<br />

c. H + (aq) + 2MnO − 4 (aq) + 5H 2 SO 3 (aq) → 2Mn 2+ (aq) + 3H 2 O(l) + 5HSO − 4 (aq)<br />

d. IO − 3 (aq) + 5I − (aq) + 6H + (aq) → 3I 2 (s) + 3H 2 O(l)<br />

9. All reference electrodes must conform to certain requirements. List the requirements <strong>and</strong> explain their<br />

significance.<br />

10. For each application, describe the reference electrode you would use <strong>and</strong> explain why. In each case, how<br />

would the measured potential compare with the corresponding E°?<br />

a. measuring the potential of a Cl − /Cl 2 couple<br />

b. measuring the pH of a solution<br />

c. measuring the potential of a MnO 4− /Mn 2+ couple<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

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