The following reaction will be used: Cr3+ (aq) + Zn (s) --> Zn2+ (aq) + Cr (s)   Standard Reduction Potentials Half-reaction Eo (V) Cr2O72- + 14 H+ + 3 e- --> 2 Cr3+ + 7 H2O  1.36 Cr3+ + e- --> Cr2+ -0.12 Cr3+ + 3e- --> Cr (s) -0.42 Cr2+ + 2e- --> Cr (s) -0.74 ZnOH+ + H+ + 2e- --> Zn (s) + H2O -0.497 Zn2+ + 2e- --> Zn (s) -0.762 ZnO(s) + H2O + 2e- --> Zn (s) + 2OH- -1.260   a) How many electrons are exchanged in a balanced redox reaction? b) What is Eocell for this reaction? c) Assuming a temperature of 19.5 oC, what would the measured voltage of this cell be if [Zn2+] = 0.001 M and [Cr3+] = 0.10 M?      What is Eocell for this reaction?

The Nernst equation allows determination of the cell potential for a galvanic cell at nonstandard conditions. Write out the Nernst equation. What are nonstandard conditions? What do , n, and Q stand for in the Nernst equation? What does the Nernst equation reduce to when a redox reaction is at equilibrium? What are the signs of G and when K 1? When K 1? When K = 1? Explain the following statement: determines spontaneity, while determines the equilibrium position. Under what conditions can you use to predict spontaneity?

Consider only the species (at standard conditions) Na+, Cl, Ag+, Ag, Zn2+, Zn, Pb in answering the following questions. Give reasons for your answers. (Use data from Table 17-1.) a. Which is the strongest oxidizing agent? b. Which is the strongest reducing agent? c. Which species can be oxidized by SO42 (aq) in acid? d. Which species can be reduced by Al(s)?

For each of the following reactions, determine the overall balanced electrochemical reaction, its standard electric potential, and the standard Gibbs energy of the reaction. aCo+F2Co2++2F bZn+Fe2+Zn2++Fe c Zn+Fe3+Zn2++Fe d Hg2++HgHg22+

The table below lists the cell potentials for the 10 possible galvanic cells assembled from the metals A. B. C. D. and E. and their respective 1.00 M 2+ ions in solution. Using the data in the table, establish a standard reduction potential table similar to Table 17-1 in the text. Assign a reduction potential of 0.00 V to the half-reaction that falls in the middle of the series. You should get two different tables. Explain why, and discuss what you could do to determine which table is correct. A(s)in A2+(aq) B(s)in B2+(aq) C(s)in V2+(aq) D(s)in D2+(aq) E(s)in E2+(aq) 0.28V 0.81V 0.13V 1.00V D(s)in D2+(aq) 0.72V 0.19V 1.13V C(s)in V2+(aq) 0.41V 0.94V B(s)in B2+(aq) 0.53V

A 0.0712-g sample of a purified organic acid was dissolved in an alcohol-water mixture and titrated with coulometrically generated hydroxide ions. With a current of 0.0392 A, 241 s was required to reach aphenolphthalein end point. Calculate the equivalent mass of the acid.

If a 2.5 A current is run through a circuit for 35 minutes, how many coulombs of charge moved through the circuit?

The measurement of pH using a glass electrode obeys the Nernst equation. The typical response of a pH meter at 25 00C is given by the equation where contains the potential of the reference electrode and all other potentials that arise in the cell that are not related to the hydrogen ion concentration. Assume that = 0.250 V and that a. What is the uncertainty in the values of pH and [H+] if the uncertainty in the measured potential is 1 m V ( 0.001 V)? b. To what precision must the potential be measured for the uncertainty in pH to be 0.02 pH unit?