Ch.19 - Electrochemistry

McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook

McMurry 8th Edition

Ch.19 - Electrochemistry

Problem 54

Chapter 19, Problem 54

Why is the cathode of a galvanic cell considered to be the positive electrode?

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Understand that a galvanic cell is a type of electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions.

Recognize that in a galvanic cell, the anode is where oxidation occurs, and the cathode is where reduction takes place.

Recall that electrons flow from the anode to the cathode through an external circuit, which is why the anode is considered the negative electrode.

At the cathode, reduction occurs, which involves the gain of electrons. This gain of electrons is associated with a positive charge because electrons are moving towards the cathode.

Therefore, the cathode is considered the positive electrode in a galvanic cell because it attracts electrons from the external circuit, completing the circuit and allowing the cell to do work.

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Key Concepts

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

Galvanic Cell

A galvanic cell is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two electrodes: an anode and a cathode, immersed in electrolyte solutions. The anode undergoes oxidation, releasing electrons, while the cathode undergoes reduction, gaining electrons. This flow of electrons from the anode to the cathode generates an electric current.

Electrode Polarity

In electrochemistry, electrodes are classified as either anodes or cathodes based on their roles in the electrochemical reaction. The anode is where oxidation occurs and is considered the negative electrode, while the cathode is where reduction takes place and is deemed the positive electrode. This distinction is crucial for understanding the direction of electron flow and the overall functioning of the cell.

Reduction and Oxidation

Reduction and oxidation are complementary processes in redox reactions. Oxidation involves the loss of electrons, while reduction involves the gain of electrons. In a galvanic cell, the cathode is the site of reduction, where electrons from the external circuit are accepted by the species in the electrolyte. This electron gain at the cathode is what makes it the positive electrode, as it attracts electrons from the anode.

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Textbook Question

Write balanced net ionic equations for the following reactions in basic solution. (b)

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An H₂/H⁺ half-cell (anode) and an Ag⁺/Ag half cell (cathode) are connected by a wire and a salt bridge. (a) Sketch the cell, indicating the direction of electron and ion flow.

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Textbook Question

Write balanced net ionic equations for the following reactions in basic solution. (c)

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Write the shorthand notation for a galvanic cell that uses the following cell reaction. Include inert electrodes if necessary.2 Fe1s2 + Cr2O72-1aq2 + 14 H+1aq2¡2 Fe3+1aq2 + 2 Cr3+1aq2 + 7 H2O1l2

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Textbook Question

Write balanced net ionic equations for the following reactions in basic solution. (b)