3. Based on the information in the table of standard reduction potentials below, what is the standard cell potential for an electrochemical cell that has iron (Fe) and magnesium (Mg) electrodes immersed in MFe and Mg solutions? Also, identify the cathode. Fe3+ + 3 e Fe +0.771 Mg2+ + 2 e-â Mg -2.37 4. An electrochemical cell is constructed with a zinc metal anode in contact with a 0.028 M solution of zinc nitrate and a silver cathode in contact with a 0.0015 Msolution of silver(I) nitrate. What is the value of Q to use in the Nernst equation for this cell? 5. An electronic device requires ten 1.50-V AA alkaline batteries, which, connected in series give 15.00 V. If the cell transfers two moles of electrons for each mole of reaction, what is the Gibbs free-energy change for the redox reaction in each of the batteries?
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Related questions
A. A voltaic cell is constructed based on the reaction of Ag(CN)2-(aq) with Cr(s) producing Ag(s) and Cr3+(s). Identify the correct cell diagram.
a. | Ag(CN)2-(aq) | Cr(s) || Ag(s) | Cr3+(aq) | d. | Ag(CN)2-(aq) | Ag(s) || Cr(s) | Cr3+(aq) |
b. | Ag(s) | Cr3+(aq) || Ag(CN)2-(aq) | Cr(s) | e. | Cr(s) | Cr3+(aq) || Ag(CN)2-(aq) | Ag(s) |
c. | Cr(s) | Cr3+(aq) || Ag(s) | Ag(CN)2-(aq) |
B. Use the table of standard reduction potentials below to identify the metal or metal ion that is the strongest oxidizing agent.
Half-reaction | |
Pb4+ + 2 e- ® Pb2+ | +1.80 |
Au3+ + 3 e- ® Au | +1.50 |
Fe3+ + 3 e- ® Fe | +0.771 |
I2 + 2 e- ® 2 I- | +0.535 |
Pb2+ + 2 e- ® Pb | -0.124 |
Al3+ + 3 e- ® Al | -1.66 |
Mg2+ + 2 e- ® Mg | -2.37 |
K+ + e- ® K | -2.93 |
a. | Pb4+ | d. | K |
b. | Pb2+ | e. | Al |
c. | K+ |
C. Silver tarnish (Ag2S) can be removed by immersing silverware in a hot solution of baking soda (NaHCO3) in a pan lined with aluminum foil; however, foul-smelling hydrogen sulfide gas (H2S) is produced. Which of the following statements is correct?
Silver/silver(I) | +0.799 |
Sulfur/hydrogen sulfide | +0.141 |
Aluminum/aluminum(III) | -1.662 |
Sodium/sodium(I) | -2.713 |
a. | Aluminum ions react with S2-, form aluminum sulfide, and gaseous carbon dioxide is released. |
b. | Silver ions in the presence of the baking soda (NaHCO3) oxidize sulfide to elemental sulfur that attacks the aluminum foil, which produces aluminum sulfide. |
c. | The aluminum acts as a reducing agent for the silver(I) in silver sulfide; then bicarbonate ion protonates the sulfide ion that is released. |
d. | Aluminum is plated onto the silver surface, making it shiny again, and then the reaction of bicarbonate with aluminum oxide releases CO2. |
e. | Silver in Ag2S reduces the aluminum, becomes metallic silver in the process, and releases hydrogen sulfide, H2S. |
D. Using the following data, determine the standard cell potential for the electrochemical cell constructed using the following reaction: Zn(s) + Pb2+(aq) ® Zn2+(aq) + Pb(s).
Half-reaction Standard reduction potential
Zn2+(aq) + 2 e- ® Zn(s) -0.763
Pb2+(aq) + 2 e- ® Pb(s) -0.126
a. | +0.637 V | d. | -0.889 V |
b. | -0.637 V | e. | +0.889 V |
c. | +1.274 V |
E. Based on the information in the table of standard reduction potentials below, what is the standard cell potential for an electrochemical cell that has iron (Fe) and magnesium (Mg) electrodes immersed in 1M Fe3+ and Mg2+ solutions? Also, identify the cathode.
Half-reaction | |
Pb4+ + 2 e- ® Pb2+ | +1.80 |
Au3+ + 3 e- ® Au | +1.50 |
Fe3+ + 3 e- ® Fe | +0.771 |
I2 + 2 e- ® 2 I- | +0.535 |
Pb2+ + 2 e- ® Pb | -0.124 |
Al3+ + 3 e- ® Al | -1.66 |
Mg2+ + 2 e- ® Mg | -2.37 |
K+ + e- ® K | -2.93 |
a. | +1.60 V with Fe as the cathode | d. | -3.14 V with Mg as the cathode |
b. | +3.14 V with Mg as the cathode | e. | +3.14 V with Fe as the cathode |
c. | -3.14 V with Fe as the cathode |
1. Consider a voltaic (galvanic) cell with the following metal electrodes. Identify which metal is the cathode and which is the anode, and calculate the cell potential.
(a) Al and Co(II)
Cathode: ____
Anode: ______
Ecell =
(b) Cd(II) and Ag(I)
cathode: ___
anode: ___
Ecell= ____
(c) Cr(III) and Sc(III)
cathode: ___
Anode:_____
Ecell:____
2. A voltaic cell contains two half-cells. One half-cell contains a titanium electrode immersed in a 1.00 M Ti(NO3)3 solution. The second half-cell contains a zinc electrode immersed in a 1.00 M Zn(NO3)2 solution.
Ti3+(aq) + 3 eâ â Ti(s) | Eâ°redâ = â1.370 V |
Zn2+(aq) + 2 eâ â Zn(s) | Eâ°redâ = â0.762 V |
(a) Using the standard reduction potentials given above, predict the standard cell potential of the voltaic cell.
(b) Write the overall balanced equation for the voltaic cell. (Include states-of-matter under the given conditions in your answer.)
3. ÎG° and E° can be said to measure the same thing, and are convertible by the equation
ÎG° = ânFEâ°cellâ
where n is the total number of moles of electrons being transferred, and F is the Faraday constant 9.64853415âââ104 C/mol. The free energy (ÎG°) of a spontaneous reaction is always negative.
For each of the electrochemical cells below, calculate the free energy of the system and state whether the reaction is spontaneous or non-spontaneous as written based on the cathode and anode assignment given. (Use the table of Standard Electrode Potentials.)
(a) The cathode is Zn(II) and the anode is Co(II).
free energy: ____ kJ
spontaneity: _____
The saturated calomel electrode, abbreviated SCE, is often used as a reference electrode in making electrochemical measurements. The SCE is composed of mercury in contact with a saturated solution of calomel Hg2Cl2. The electrolyte solution is KCl. ESCE is +0.242 V relative to standard hydrogen electrode.
Calculate the potential for each of the galvanic cells containing a saturated calomel electrode and the given half-cell components at standard conditions. In each case indicate whether the SCE is the cathode or the anode. Standard reduction potentials are found in table:
Electrode |
SCE |
a) Cu2+ + 2e- → Cu | b) Fe3+ + e- → Fe2+ | c) AgCl + e- → Ag + Cl- | d) Al3+ + 3e- → Al | e) Ni2+ + 2e- → Ni |
Eo |
+0.242 V |
+ 0.339 V | + 0.771 V | + 0.223 V | - 1.677 V | - 0.257 V |