Note: Two of the Problems Will Be Graded and Counted As a Quiz

Chemistry 11

Homework

Electrochemistry II

Name: ______

Note: Two of the problems will be graded and counted as a quiz.

(1) A galvanic cell is based on the following half-reactions at 25ºC:

Ag+ + e- ® Ag

H2O2 + 2H+ + 2e- ® 2H2O

Predict whether ecell is larger or smaller than eºcell for the following cases.

a. [Ag+] = 1.0 M, [H2O2] = 2.0 M, [H+] = 2.0 M

b. [Ag+] = 2.0 M, [H2O2] = 1.0 M, [H+] = 1.0 x 10-7 M

(2) Consider a concentration cell based on Ag+. If the concentration of Ag+ in one compartment is 1.0 M, calculate the cell potential at 25ºC when the concentration of Ag+ in the other compartment is the following.

a. 1.0 M

b. 2.0 M

c. 0.10 M

(3) Can the permanganate ion oxidize Fe2+ to Fe3+ at 25ºC under the following conditions?

[Mn2+] = 1 x 10-6 M [MnO4-] = 0.01 M [Fe2+] = 1 x 10-3 M

[Fe3+] = 1 x 10-6 M pH = 4.0

(4) Consider the cell described below:

Al ïAl3+ (1.00 M) ïï Pb+2 (1.00 M) ï Pb

Calculate the cell potential after the reaction has operated long enough for the [Al3+] to have change by 0.60 M. T = 25ºC.

(5) Consider the galvanic cell based on the following half-reactions:

Au3+ + 3e- ® Au eº = 1.50 V

Tl+ + e- ® Tl eº = –0.34 V

a. Determine the overall cell reaction and calculate eºcell.

b. Calculate ΔGº and K for the reaction at 25ºC.

c. Calculate ecell at 25ºC when [Au3+] = 1.0 x 10-2 M and [Tl+] = 1.0 x 10-4 M.

(6) Calculate the value of the solubility product (Ksp) for CdS given the following potentials:

CdS + 2e- ® Cd + S2- eº = –1.21 V

Cd2+ + 2e- ® Cd eº = –0.402 V

(7) How long will it take to plate out each of the following with a current of 100.0 A?

a. 1.0 kg Al from Al3+(aq)

b. 5.0 mol Ag from Ag+(aq)

(8) It took 74.6s for a 2.50 amp current to plate 0.1086g of a metal from solution containing M2+ ions. What is the metal?

(9) What volume of F2 gas, at 25ºC and 1.00 atm, is produced when molten KF is electrolyzed by a current of 10.0 amp for 2.00 hours? What mass of potassium metal is produced? At which electrode does each reaction occur?

(10) What reactions take place at the cathode and anode when each of the following is electrolyzed? Assume 25°C and a neutral pH.

a. 1.0 M NiBr2 solution

b. 1.0 M AlF3 solution

(11) What reactions occur at the anode and cathode when an acidic aqueous solution of FeSO4 is electrolyzed? Use standard reduction potentials to justify you answers.