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Ch.20 - Electrochemistry
All textbooksBrown 14th EditionCh.20 - ElectrochemistryProblem 114
Chapter 20, Problem 114

A voltaic cell is based on Ag+ (aq) > Ag (s) and Fe3+ (aq) > Fe2+ (aq) half-cells. Use S° values in Appendix C and the relationship between cell potential and free-energy change to predict whether the standard cell potential increases or decreases when the temperature is raised above 25 °C.

Verified step by step guidance
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Step 1: Identify the half-reactions involved in the voltaic cell. The given half-reactions are Ag^+ (aq) + e^- -> Ag (s) and Fe^3+ (aq) + e^- -> Fe^2+ (aq).
Step 2: Determine the standard cell potential (E°) for the cell by using the standard reduction potentials from a reference table. Calculate E° = E°(cathode) - E°(anode).
Step 3: Use the Nernst equation to understand how cell potential (E) changes with temperature. The Nernst equation is E = E° - (RT/nF) * ln(Q), where R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons transferred, F is Faraday's constant, and Q is the reaction quotient.
Step 4: Consider the entropy change (ΔS°) for the cell reaction. Use the relationship ΔG° = ΔH° - TΔS° and ΔG° = -nFE° to relate entropy change to cell potential.
Step 5: Analyze how an increase in temperature affects the cell potential. If ΔS° is positive, increasing temperature will increase the cell potential, and if ΔS° is negative, increasing temperature will decrease the cell potential.
Related Practice
Open Question
In a galvanic cell, the cathode is an Ag+ | 1.00 M | Ag(s) half-cell. The anode is a standard hydrogen electrode immersed in a buffer solution containing 0.10 M benzoic acid (C6H5COOH) and 0.050 M sodium benzoate (C6H5COO-Na+). The measured cell voltage is 1.030 V. What is the pKa of benzoic acid?
Textbook Question

Aqueous solutions of ammonia 1NH32 and bleach (active ingredient NaOCl) are sold as cleaning fluids, but bottles of both of them warn: 'Never mix ammonia and bleach, as toxic gases may be produced.' One of the toxic gases that can be produced is chloroamine, NH2Cl. (b) What is the oxidation number of chlorine in chloramine?

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Textbook Question

Aqueous solutions of ammonia 1NH32 and bleach (active ingredient NaOCl) are sold as cleaning fluids, but bottles of both of them warn: 'Never mix ammonia and bleach, as toxic gases may be produced.' One of the toxic gases that can be produced is chloroamine, NH2Cl. (e) Is N oxidized, reduced, or neither, upon the conversion of ammonia to nitrogen trichloride?

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Open Question
Hydrogen gas has the potential for use as a clean fuel in reaction with oxygen. The relevant reaction is 2 H2(g) + O2(g) → 2 H2O(l). Consider two possible ways of utilizing this reaction as an electrical energy source: (i) Hydrogen and oxygen gases are combusted and used to drive a generator, much as coal is currently used in the electric power industry; (ii) hydrogen and oxygen gases are used to generate electricity directly by using fuel cells that operate at 85 °C. Based on the analysis here, would it be more efficient to use the combustion method or the fuel-cell method to generate electrical energy from hydrogen?
Textbook Question

Cytochrome, a complicated molecule that we will represent as CyFe2+, reacts with the air we breathe to supply energy required to synthesize adenosine triphosphate (ATP). The body uses ATP as an energy source to drive other reactions (Section 19.7). At pH 7.0 the following reduction potentials pertain to this oxidation of CyFe2+: O21g2 + 4 H+1aq2 + 4 e- ¡ 2 H2O1l2 Ered ° = +0.82 V CyFe3+1aq2 + e- ¡ CyFe2+1aq2 E°red = +0.22 V (a) What is ∆G for the oxidation of CyFe2+ by air? (b) If the synthesis of 1.00 mol of ATP from adenosine diphosphate (ADP) requires a ∆G of 37.7 kJ, how many moles of ATP are synthesized per mole of O2?

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Textbook Question

Cytochrome, a complicated molecule that we will represent as CyFe2+, reacts with the air we breathe to supply energy required to synthesize adenosine triphosphate (ATP). The body uses ATP as an energy source to drive other reactions (Section 19.7). At pH 7.0 the following reduction potentials pertain to this oxidation of CyFe2+: O21g2 + 4 H+1aq2 + 4 e- ¡ 2 H2O1l2 Ered ° = +0.8 (b) If the synthesis of 1.00 mol of ATP from adenosine diphosphate (ADP) requires a ∆G of 37.7 kJ, how many moles of ATP are synthesized per mole of O2?

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