Calculate
Interpretation:
The standard cell potential, emf of the galvanic cell, and free energy change for the given cell reactions at
are to be determined.
Concept introduction:
Gibbs free energy is the change in the enthalpy
According to the standard reduction potential values, the electrode that has lower negative reduction potential will act as a cathode and will undergo reduction. However, if the negative reduction potential of the electrode is high, it will act as an anode and will undergo oxidation.
The standard reduction potential of a galvanic cell may be calculated in terms of standard reduction potential of cathode and anode, as the relation mentioned below:
According to the Nernst equation, the relation between emf, standard cell potential, and reaction quotient at
will be as follows:
Here,
The relation between cell potential and free energy change is as follows:
Here,
is the Gibb’s free energy change,
is the Faraday constant
Answer to Problem 30QP
Solution:
(a)
(b)
Explanation of Solution
a)
The overall reaction of galvanic cell is as follows:
The half-cell reactions of
Oxidation half reaction (Anode):
Reduction half reaction (Cathode):
As the standard reduction potential of
half-cell reaction is less (more negative); therefore, it will act as an anode and will undergo oxidation.
Therefore,
The cell representation of a galvanic cell is as follows:
The standard cell potential that is
(at
) for the above galvanic cell is calculated as follows:
The reaction quotient for the reaction is given by the following expression:
Concentration of
and
is
and
Substitute all the values in the above equation,
In the given galvanic cell, the total loss and total gain of electrons is two.
Now, according to the Nernst equation, the relation between emf, standard cell potential, and reaction quotient at
will be as follows:
Substitute all the values in the above equation,
The relation between cell potential and free energy change is as follows:
Substitute all the values in the above equation,
b)
The overall reaction of galvanic cell is as follows:
The half-cell reactions of
Oxidation half reaction (Anode):
Reduction half reaction (Cathode):
As the standard reduction potential of
half-cell reaction is greater (less negative), it will act as a cathode and will undergo reduction. However, the standard reduction potential of
half-cell reaction is less (more negative); therefore, it will act as an anode and will undergo oxidation.
Therefore,
The cell representation of a galvanic cell is as follows:
The standard cell potential that is
(at
) for the above galvanic cell is calculated as follows:
The reaction quotient for the reaction is as follows:
Concentration of
and
is
and
Substitute all the values in the above expression,
In the given galvanic cell, the total loss of electron and total gain of electron is six.
Now, according to the Nernst equation, the relation between emf, standard cell potential, and reaction quotient at
will be as follows:
On substituting all the values in the above equation,
The relation between cell potential and free energy change is as follows:
Substitute the values of
Want to see more full solutions like this?
Chapter 19 Solutions
Aleks 360 Access Card 1 Semester For Introductory Chemistry
- For each reaction listed, determine its standard cell potential at 25 C and whether the reaction is spontaneous at standard conditions. (a) Mn(s)+Ni2+(aq)Mn2+(aq)+Ni(s) (b) 3Cu2+(aq)+2Al(s)2Al3+(aq)+3Cu(s) (c) Na(s)+LiNO3(aq)NaNO3(aq)+Li(s) (d) Ca(NO3)2(aq)+Ba(s)Ba(NO3)2(aq)+Ca(s)arrow_forwardFor a certain cell, G=25.0 kJ. Calculate E° if n is (a) 1(b)1(c) 41 Comment on the effect that the number of electrons exchanged has on the voltage of a cell.arrow_forwardAn electrolysis experiment is performed to determine the value of the Faraday constant (number of coulombs per mole of electrons). In this experiment, 28.8 g of gold is plated out from a AuCN solution by running an electrolytic cell for two hours with a current of 2.00 A. What is the experimental value obtained for the Faraday Constant?arrow_forward
- What is the voltage of a concentration cell of Fe2+ ions where the concentrations are 0.0025 and 0.750 M? What is the spontaneous reaction?arrow_forwardCalculate the standard cell potential of the cell corresponding to the oxidation of oxalic acid, H2C2O4, by permanganate ion. MnO4. 5H2C2O4(aq)+2MnO4(aq)+6H+(aq)10CO2(g)+2Mn2+(aq)+8H2O(l) See Appendix C for free energies of formation: Gf for H2C2O4(aq) is 698 kJ.arrow_forwardConsider a voltaic cell in which the following reaction takes place in basic medium at 25°C. 2NO3-(aq)+3S2(aq)+4H2O3S(s)+2NO(g)+8OH(aq) (a) Calculate E°. (b) Write the Nernst equation for the cell E. (c) Calculate E under the following conditions: PNO=0.994atm,ph=13.7,[S2]=0.154M,[NO3-]=0.472M, .arrow_forward
- What is the cell potential (Ecell) of a spontaneous cell that is run at 25C and contains [Cr3+] = 0.10 M and [Ag+] = 1.0 104 M?arrow_forwardIt took 150. s for a current of 1.25 A to plate out 0.109 g of a metal from a solution containing its cations. Show that it is not possible for the cations to have a charge of 1+.arrow_forwardCalculate the cell potential of a cell operating with the following reaction at 25C, in which [MnO4] = 0.010 M, [Br] = 0.010 M. [Mn2] = 0.15 M, and [H] = 1.0 M. 2MNO4(aq)+10Br(aq)+16H+(aq)2MN2(aq)+5Br2(l)+8H2O(l)arrow_forward
- Consider a voltaic cell in which the following reaction takes place. 2F2+(aq)+H2O2(aq)+2H+(aq)2Fe3+(aq)+2H2O (a) Calculate E°. (b) Write the Nernst equation for the cell. (c) Calculate E at 25°C under the following conditions: [Fe2+]=0.00813M,[H2O2]=0.914M,[Fe3+]=0.199M,ph=2.88 .arrow_forwardA current of 0.0100 A is passed through a solution of rhodium sulfate, causing reduction of the metal ion to the metal. After 3.00 hours, 0.038 g of Rh has been deposited. What is the charge on the rhodium ion, Rhn+? What is the formula for rhodium sulfate?arrow_forwardConsider a voltaic cell in which the following reaction occurs. Zn(s)+Sn2+(aq)Zn2+(aq)+Sn(s) (a) Calculate E° for the cell. (b) When the cell operates, what happens to the concentration of Zn2+? The concentration of Sn2+? (c) When the cell voltage drops to zero, what is the ratio of the concentration of Zn2+ to that of Sn2+? (d) If the concentration of both cations is 1.0 M originally, what are the concentrations when the voltage drops to zero?arrow_forward
- General Chemistry - Standalone book (MindTap Cour...ChemistryISBN:9781305580343Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; DarrellPublisher:Cengage LearningChemistry: Principles and PracticeChemistryISBN:9780534420123Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward MercerPublisher:Cengage LearningChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage Learning
- ChemistryChemistryISBN:9781305957404Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCostePublisher:Cengage LearningChemistry by OpenStax (2015-05-04)ChemistryISBN:9781938168390Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark BlaserPublisher:OpenStaxChemistry: An Atoms First ApproachChemistryISBN:9781305079243Author:Steven S. Zumdahl, Susan A. ZumdahlPublisher:Cengage Learning