Ch.20 - Electrochemistry

Brown - Chemistry: The Central Science 15th Edition

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Brown 15th Edition

Ch.20 - Electrochemistry

Problem 33f

Chapter 20, Problem 33f

A voltaic cell similar to that shown in Figure 20.5 is constructed. One electrode half-cell consists of a silver strip placed in a solution of AgNO3, and the other has an iron strip placed in a solution of FeCl2. The overall cell reaction is Fe1s2 + 2 Ag+1aq2 ¡ Fe2+1aq2 + 2 Ag1s2 (f) In which directions do the cations and anions migrate through the solution?

Verified step by step guidance

Identify the anode and cathode in the voltaic cell. In this case, the anode is the iron (Fe) electrode, and the cathode is the silver (Ag) electrode.

Determine the oxidation and reduction half-reactions. At the anode, iron is oxidized: Fe(s) -> Fe^2+(aq) + 2e^-. At the cathode, silver ions are reduced: 2Ag^+(aq) + 2e^- -> 2Ag(s).

Understand the flow of electrons. Electrons flow from the anode (Fe) to the cathode (Ag) through the external circuit.

Analyze the migration of ions through the salt bridge. Cations (Fe^2+) will migrate towards the cathode compartment to balance the charge, while anions (NO3^-) will migrate towards the anode compartment.

Summarize the ion migration: Fe^2+ ions move towards the Ag electrode compartment, and NO3^- ions move towards the Fe electrode compartment to maintain electrical neutrality.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Voltaic Cell

A voltaic cell, or galvanic cell, is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two half-cells, each containing an electrode and an electrolyte. The flow of electrons occurs from the anode (where oxidation happens) to the cathode (where reduction occurs), generating an electric current.

Ion Migration

In a voltaic cell, cations (positively charged ions) migrate towards the cathode, while anions (negatively charged ions) move towards the anode. This migration is essential for maintaining charge balance in the cell as the redox reactions proceed. In the given reaction, Ag+ ions will move towards the cathode where reduction occurs, while the anions from the salt bridge will migrate to the anode.

Redox Reactions

Redox reactions involve the transfer of electrons between two species, resulting in oxidation (loss of electrons) and reduction (gain of electrons). In the provided cell reaction, iron is oxidized to Fe2+ while silver ions are reduced to solid silver. Understanding the oxidation states and the flow of electrons is crucial for predicting the behavior of the cell and the direction of ion migration.

Related Practice

Textbook Question

Complete and balance the following equations, and identify the oxidizing and reducing agents. (Recall that the O atoms in hydrogen peroxide, H2O2, have an atypical oxidation state.) H2O21aq2 + ClO21aq2 ¡ ClO2-1aq2 + O21g2 (basic solution)

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Textbook Question

Complete and balance the following equations, and identify the oxidizing and reducing agents:

a. MnO4−(𝑎𝑞)+CH3OH(𝑎𝑞)⟶Mn2+(𝑎𝑞)+HCOOH(𝑎𝑞)(acidic solution)

b. As2O3(𝑠)+NO3−(𝑎𝑞)⟶H3AsO4(𝑎𝑞)+N2O3(𝑎𝑞)(acidic solution)

c. Pb(OH)42−(𝑎𝑞)+ClO−(𝑎𝑞)⟶PbO2(𝑠)+Cl−(𝑎𝑞)(basic solution)

Textbook Question

Complete and balance the following equations, and identify the oxidizing and reducing agents: As₂O₃(s) + NO₃^-(aq) → H₃AsO₄(aq) + N₂O₃(aq) (acidic solution)

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Textbook Question

(a) What is the definition of the volt?

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Textbook Question

(b) Do all voltaic cells produce a positive cell potential?

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