![Chemistry: Principles and Reactions](https://www.bartleby.com/isbn_cover_images/9781305079373/9781305079373_largeCoverImage.gif)
Concept explainers
Consider the reaction low at 25°C:
Use Table 17.1 to answer the following questions. Support your answers with calculations.
(a) Is the reaction spontaneous at standard conditions?
(b) Is the reaction spontaneous at a pH of 3.00 with all other ionic species at 0.100 M and all gases at 1.00 atm?
(c) Is the reaction spontaneous at a pH of 8.00 with all other ionic species at 0.100 M and all gases at 1.00 atm?
(d) At what pH is the reaction at equilibrium with all other ionic species at 0.100 M and all gases at 1.00 atm?
![Check Mark](/static/check-mark.png)
(a)
Interpretation:
The following redox reaction needs to be classified as spontaneous or non-spontaneous under standard conditions
Concept introduction:
The chemical reactions that take place in an electrochemical cell are redox reactions i.e. oxidation (loss of electrons) at the anode and reduction (gain of electrons) at the cathode The standard voltage (E°) for the cell is the sum of the standard voltages of the reduction
A given redox reaction is spontaneous if the calculated voltage is positive and non-spontaneous if the cell voltage is negative
Answer to Problem 74QAP
E° = +0.899 V. Since the value is positive, the reaction will be spontaneous under standard conditions.
Explanation of Solution
The given redox reaction is:
Here Cr gets oxidized as the oxidation state changes from 0 to +3.
Sulfur, S gets reduced as the oxidation state changes from +6 to +4
Calculation:
The half reactions are as follows:
Overall reaction can be obtained by multiplying the anode reaction by 2 and cathode by 3,
The total number of electrons involved will be 6.
Since,
The reaction is spontaneous.
![Check Mark](/static/check-mark.png)
(b)
Interpretation:
The following redox reaction needs to be classified as spontaneous or non-spontaneous at a pH = 3.0, concentration of ionic species = 0.100 M and gases at 1.00 atm pressure.
Concept introduction:
The cell voltage under non-standard conditions (E) is related to the standard voltage (E°) via the Nernst equation:
A given redox reaction is spontaneous if the calculated voltage is positive and non-spontaneous if the cell voltage is negative
Answer to Problem 74QAP
E° = +0.534 V. Since the value is positive, the reaction will be spontaneous under the given pH, concentration and pressure conditions
Explanation of Solution
The given redox reaction is:
Based on the Nernst equation:
The concentration or activity of solid and liquid species are taken equal to 1 thus,
Since,
Now,
Putting the values,
Since,
The reaction is spontaneous.
![Check Mark](/static/check-mark.png)
(c)
Interpretation:
The following redox reaction needs to be classified as spontaneous or non-spontaneous at a pH = 8.0, concentration of ionic species = 0.100 M and gases at 1.00 atm pressure
Concept introduction:
The cell voltage under non-standard conditions (E) is related to the standard voltage (E°) via the Nernst equation:
A given redox reaction is spontaneous if the calculated voltage is positive and non-spontaneous if the cell voltage is negative.
Answer to Problem 74QAP
E° = -0.058 V. Since the value is negative the reaction will be non-spontaneous under the given pH, concentration and pressure conditions
Explanation of Solution
The given redox reaction is:
Based on the Nernst equation:
Also,
Also,
Putting the values,
The reaction will be non-spontaneous.
![Check Mark](/static/check-mark.png)
(d)
Interpretation:
The pH at which the redox reaction will reach equilibrium given that the concentration of ions is 0.100 M and pressure of gasesis 1.00 atm, needs to be determined.
Concept introduction:
The cell voltage under non-standard conditions (E) is related to the standard voltage (E°) via the Nernst equation:
A given redox reaction is spontaneous if the calculated voltage is positive and non-spontaneous if the cell voltage is negative.
Answer to Problem 74QAP
The reaction reaches equilibrium at pH = 7.51
Explanation of Solution
The given redox reaction is:
Based on the Nernst equation:
Here,
Putting the values,
Want to see more full solutions like this?
Chapter 17 Solutions
Chemistry: Principles and Reactions
- Actually, the carbon in CO2(g) is thermodynamically unstable with respect to the carbon in calcium carbonate(limestone). Verify this by determining the standardGibbs free energy change for the reaction of lime,CaO(s), with CO2(g) to make CaCO3(s).arrow_forwardCalcium metal can be obtained by the direct electrolysis of molten CaCl2, at a voltage of 3.2 V. (a) How many joules of electrical energy are required to obtain 12.0 1b of calcium? (b) What is the cost of the electrical energy obtained in (a) if electrical energy is sold at the rate of nine cents per kilowatt hour?arrow_forwardOrder the following oxidizing agents by increasing strength under standard-state conditions: Mg2+(aq), Hg2+(aq), Pb2+(aq).arrow_forward
- Calculate K at 25°C for each of the reactions referred to in Question 31.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_forwardA 1.0-L sample of 1.0 M HCl solution has a 10.0 A current applied for 45 minutes. What is the pH of the solution after the electricity has been turned off?arrow_forward
- When carbon dioxide dissolves in water it reacts to produce carbonic acid, H2CO3(aq), which can ionize in two steps. H2CO3(aq)HCO3(aq)+H+(aq)Kc1=4.2107HCO3(aq)CO32(aq)+H+(aq)Kc2=4.81011 Calculate the equilibrium constant for the reaction H2CO3(aq)CO32(aq)+2H+(aq)arrow_forwardAn electrode is prepared from liquid mercury in contact with a saturated solution of mercury(I) chloride, Hg2Cl, containing 1.00 M Cl . The cell potential of the voltaic cell constructed by connecting this electrode as the cathode to the standard hydrogen half-cell as the anode is 0.268 V. What is the solubility product of mercury(I) chloride?arrow_forwardHow is the pH scale defined? What range of pH values corresponds to acidic solutions? What range corresponds to basic solutions? Why is pH = 7.00 considered neutral? When the pH of a solution changes by one unit, by what factor does the hydrogen ion concentration change in the solution? How is pOH defined? How arc pH and pOH for a given solution related? Explain.arrow_forward
- Consider the following cell running under standard conditions: Fe(s)Fe2+(aq)Al3+(aq)Al(s) a Is this a voltaic cell? b Which species is being reduced during the chemical reaction? c Which species is the oxidizing agent? d What happens to the concentration of Fe3+(aq) as the reaction proceeds? e How does the mass of Al(s) change as the reaction proceeds?arrow_forwardWhat is the standard cell potential you would obtain from a cell at 25C using an electrode in which Hg22+(aq) is in contact with mercury metal and an electrode in which an aluminum strip dips into a solution of Al3+(aq)?arrow_forwardConsider the following cell reaction at 25C. 2Cr(s)+3Fe2+(aq)2Cr3+(aq)+3Fe(s) Calculate the standard cell potential of this cell from the standard electrode potentials, and from this obtain G for the cell reaction. Use data in Appendix C to calculate H; note that Cr(H2O)63+(aq) equals Cr3+(aq). Use these values of H and G to obtain S for the cell reaction.arrow_forward
- Chemistry for Engineering StudentsChemistryISBN:9781337398909Author:Lawrence S. Brown, Tom HolmePublisher:Cengage LearningGeneral 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: The Molecular ScienceChemistryISBN:9781285199047Author:John W. Moore, Conrad L. StanitskiPublisher:Cengage Learning
- Chemistry: Principles and PracticeChemistryISBN:9780534420123Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward MercerPublisher:Cengage LearningIntroductory Chemistry: A FoundationChemistryISBN:9781337399425Author:Steven S. Zumdahl, Donald J. DeCostePublisher:Cengage LearningChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage Learning
![Text book image](https://www.bartleby.com/isbn_cover_images/9781337398909/9781337398909_smallCoverImage.gif)
![Text book image](https://www.bartleby.com/isbn_cover_images/9781305580343/9781305580343_smallCoverImage.gif)
![Text book image](https://www.bartleby.com/isbn_cover_images/9781285199047/9781285199047_smallCoverImage.gif)
![Text book image](https://www.bartleby.com/isbn_cover_images/9780534420123/9780534420123_smallCoverImage.gif)
![Text book image](https://www.bartleby.com/isbn_cover_images/9781337399425/9781337399425_smallCoverImage.gif)
![Text book image](https://www.bartleby.com/isbn_cover_images/9781305079373/9781305079373_smallCoverImage.gif)