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Ch.19 - Electrochemistry
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145당신이 사용하는 게 아니라요?교과서 변경
19장, 문제 162c

The half-reactions that occur in ordinary alkaline batteries can be written as In 1999, researchers in Israel reported a new type of alkaline battery, called a 'super-iron' battery. This battery uses the same anode reaction as an ordinary alkaline battery but involves the reduction of FeO42- ion (from K2FeO4) to solid Fe(OH)3 at the cathode. (c) A super-iron battery should last longer than an ordinary alkaline battery of the same size and weight because its cathode can provide more charge per unit mass. Quan-titatively compare the number of coulombs of charge released by the reduction of 10.0 g K2FeO4 to Fe(OH)3 with the number of coulombs of charge released by the reduction 10.0 g of MnO2 to MnO(OH).

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1
Determine the molar mass of K_2FeO_4 and MnO_2.
Calculate the number of moles of K_2FeO_4 and MnO_2 in 10.0 g of each substance using their respective molar masses.
Write the balanced half-reaction for the reduction of FeO_4^{2-} to Fe(OH)_3 and MnO_2 to MnO(OH).
Determine the number of electrons transferred in each half-reaction.
Calculate the total charge in coulombs for each reaction using the formula: Charge (C) = moles of electrons × Faraday's constant (96485 C/mol).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Half-Reactions in Electrochemistry

Half-reactions are the individual oxidation or reduction processes that occur in an electrochemical cell. In a battery, the anode undergoes oxidation while the cathode undergoes reduction. Understanding these half-reactions is crucial for analyzing the overall cell reaction and calculating the charge produced during the battery's operation.
추천 영상:
가이드 코스
01:49
First-Order Half-Life

Molar Mass and Stoichiometry

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole. Stoichiometry involves the calculation of reactants and products in chemical reactions based on their molar ratios. In this context, knowing the molar masses of K2FeO4 and MnO2 is essential for determining how many moles are present in 10.0 g, which directly affects the charge calculations.
추천 영상:
가이드 코스
02:11
Molar Mass Concept

Coulombs and Charge Calculation

A coulomb is the unit of electric charge, defined as the amount of charge transported by a constant current of one ampere in one second. The total charge produced in a reaction can be calculated using Faraday's laws of electrolysis, which relate the amount of substance transformed at an electrode to the total electric charge passed through the cell. This concept is vital for comparing the charge output of the two different battery reactions.
추천 영상:
가이드 코스
01:15
Coulomb's Law Concept 2
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교과서 질문

The half-reactions that occur in ordinary alkaline batteries can be written as In 1999, researchers in Israel reported a new type of alkaline battery, called a 'super-iron' battery. This battery uses the same anode reaction as an ordinary alkaline battery but involves the reduction of FeO42- ion (from K2FeO4) to solid Fe(OH)3 at the cathode. (a) Use the following standard reduction potential and any data from Appendixes C and D to calculate the standard cell potential expected for an ordinary alkaline battery:

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교과서 질문

We've said that the +1 oxidation state is uncommon for indium but is the most stable state for thallium. Verify this statement by calculating E ° and ΔG ° (in kilojoules) for the disproportionation reaction

3 M+1aq2S M3+1aq2 + 2 M1s2 M = In or Tl

Is disproportionation a spontaneous reaction for In+ and/orTl+? Standard reduction potentials for the relevant halfreactions are

In3+1aq2 + 2 e- S In+1aq2 E° = -0.44 V

In+1aq2 + e- S In1s2 E° = -0.14 V

Tl3+1aq2 + 2 e- S Tl+1aq2 E° = +1.25 V

Tl+1aq2 + e- S Tl1s2 E° = -0.34 V

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교과서 질문

The half-reactions that occur in ordinary alkaline batteries can be written as In 1999, researchers in Israel reported a new type of alkaline battery, called a 'super-iron' battery. This battery uses the same anode reaction as an ordinary alkaline battery but involves the reduction of FeO42- ion (from K2FeO4) to solid Fe(OH)3 at the cathode. (b) Write a balanced equation for the cathode half-reaction in a super-iron battery. The half-reaction occurs in a basic environment.

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교과서 질문
Consider the redox titration of 100.0 mL of a solution of 0.010 M Fe2+ in 1.50 M H2SO4 with a 0.010 M solution of KMnO4, yielding Fe3+ and Mn2+. The titration is carried out in an electrochemical cell equipped with a platinum electrode and a calomel reference electrode consisting of an Hg2Cl2/Hg electrode in contract with a saturated KCl solution having [Cl-] = 2.9M. Using any data in Appendixes C and D, calculate the cell potential after addition of (a) 5.0 mL, (b) 10.0mL, (c) 19.0 mL, and (d) 21.0 mL of the KMnO4 solution.
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교과서 질문

Experimental solid-oxide fuel cells that use butane (C4H10) as the fuel have been reported recently. These cells contain composite metal/metal oxide electrodes and a solid metal oxide electrolyte. The cell half-reactions are (c) How many grams of butane are required to produce a constant current of 10.5 A for 8.00 h? How many liters of gaseous butane at 20 °C and 815 mm Hg pressure are required?

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교과서 질문
Gold metal is extracted from its ore by treating the crushed rock with an aerated cyanide solution. The unbalanced equation for the reaction is (b) Use any of the following data at 25 °C to calculate ∆G° for this reaction at 25 °C: Kf for Au(CN)2- = 6.2 x 10^38, Ka for HCN = 4.9 x 10^-10, and standard reduction potentials are
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