CHEM 241 Electrochemistry

Which of the following shows the correct order of increasing strength as an oxidizing agent?

K+ (aq) < MnO4- (aq) < O3 (g)

What is the pH of the standard hydrogen electrode?

pH = 0

What is the correct cell notation for the reaction below?

Cu2+ (aq) + Pb (s) ⇔ Cu (s) + Pb2+ (aq)

Pb (s) I Pb2+ (aq) II Cu2+ (aq) I Cu (s)

Calculate standard cell potential for the following reaction:

MnO4- (aq) + 8 H+ (aq) + 5 Fe2+ ⇔ Mn2+ + 4 H2O (l) + 5 Fe3+(aq)

Standard Half Reduction Potentials:

Eo (Fe2+/Fe3+) = + 0.771 V

Eo (MnO4-/Mn2+) = + 1.507 V

+ 0.736 V

In Question 5, which of the below species is the reducing agent?

Fe2+

For the silver half-reaction, Ag+(aq)+ e- -> Ag (s), when the concentration of silver cation is increased, the reduction potential:

THINK Nernst Equation

becomes more positive.

Calculate the equilibrium constant for the reaction between Sn metal and Zn2+ solution.

Sn + Zn2+ ⇋ Sn2+ + Zn

Sn2+ + 2 e− → Sn (s) E° = −0.141 V

Zn2+ + 2 e− → Zn (s) E° = −0.762 V

1.21 x 10-21

Calculate cell potential (Ecell) for the electrochemical cell shown below at 25 oC.

Pt | Fe2+ (4.25 x 10-3 M), Fe3+ (1.50 x 10-3 M) || MnO4- (6.50 x 10-3 M), Mn2+ (2.00 x 10-2 M), H+ (0.100 M) | Pt

Hint: Nernst Equation

Standard Half Reduction Potentials:

Eo (Fe3+/Fe2+) = 0.771 V

Eo (MnO4-/Mn2+) = 1.51 V.

+0.665 V

Calculate the cell potential given the following electrochemical cell at 25 oC.

Cu (s) I Cu2+ (aq) (0.236 M) II Cu2+ (aq) (0.875 M) I Cu (s)

+ 0.0168 V

The mercury cell used to power a heart pacemaker runs on the following reaction:Zn (s) + HgO (s) → ZnO (s) + Hg (l) E° = 1.35 voltsThe power required to operate the pacemaker is 0.00800 Watts. How many days will this cell run on 56 grams of HgO? (Zn is present in excess, MW of HgO = 216.59 g/mole)

97

An electrochemical cell is constructed based on the below reaction. Under standard conditions, calculate ΔG° for the following reaction. In the half cell with the Fe3+ & Fe2+, a Pt electrode is used. The cell is constructed like all typical Galvanic cells.

Ni2+ (aq) + 2 Fe2+ (aq) ⇔ Ni (s) + 2 Fe3+ (aq)

Standard Half Reduction Potentials:

Eo (Fe3+/Fe2+) = + 0.771 V

Eo (Ni2+/Ni) = - 0.236 V

+ 194,3 kJ

If an indicator electrode measures a potential relative to the S.C.E. of -0.461 V, what is the potential relative to the Ag/AgCl reference electrode? (remember: Ag/AgCl ref sat'd KCl)

-0.417 v

An electrode with fixed potential is referred to in potentiometry as the:

reference electrode

The is the voltage difference when two dissimilar electrolyte solutions are in contact.

Junction Potential

Which is NOT a class of ion-selective electrode?

biochemical electrode

Which amino acid or amino acids is(are) present predominately as a zwitterion when dissolved in a pH 7.00 solution? Click on the link to see the attached figure with the structures you need to use for this question. You can make multiple selections for each attempt.

Isoleucine and Cysteine

Which of the following would be classified as the strongest reducing agent?

Y(s)

In the following reaction,

Fe2+(aq) + Ag+(aq) ⇋ Fe3+(aq) + Ag(s)

Fe2+ is oxidized and Ag+ is reduced.

If a spontaneous electrochemical cell is set up in a circuit with wires and a voltmeter, electrons flow OUT OF which electrode (half-cell)?

anode

Calculate the cell potential given the following electrochemical cell at 25 oC.

Cu (s) I Cu2+ (aq) (0.236 M) II Cu2+ (aq) (0.875 M) I Cu (s)

+0.0168 V

Calculate cell potential (Ecell) for the electrochemical cell shown below at 25 oC.

Pt | Fe2+ (4.25 x 10-3 M), Fe3+ (1.50 x 10-3 M) || MnO4- (6.50 x 10-3 M), Mn2+ (2.00 x 10-2 M), H+ (0.100 M) | Pt

Standard Half Reduction Potentials:

Eo (Fe3+/Fe2+) = 0.771 V

Eo (MnO4-/Mn2+) = 1.51 V.

+ 0.665 V

In the reaction MnO4- + 8 H+ + 5e- ⇔ Mn2+ + 4 H2O, the manganese in 3.95 grams of KMnO4 is reduced to Mn2+. How many coulombs of charge must have been transferred to the permanganate ion (MnO4-)?

1.20 x 104 C