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Ch.20 - Electrochemistry
Tro - Chemistry: A Molecular Approach 5th Edition
Tro5th EditionChemistry: A Molecular ApproachISBN: 9780134874371Not the one you use?Change textbook
All textbooksTro 5th EditionCh.20 - ElectrochemistryProblem 47d
Chapter 20, Problem 47d

Consider the voltaic cell:
Diagram of a galvanic cell showing anode, cathode, and salt bridge with ion flow directions.
d. Indicate the direction of anion and cation flow in the salt bridge

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Identify the anode and cathode in the voltaic cell. In this diagram, Pb is the anode and Ag is the cathode.
Recall that oxidation occurs at the anode and reduction occurs at the cathode. Therefore, Pb is oxidized to Pb2+ and Ag+ is reduced to Ag.
Understand that the salt bridge is used to maintain electrical neutrality by allowing the flow of ions between the two half-cells.
Determine the direction of ion flow: anions (negative ions) will flow towards the anode to balance the positive charge of the Pb2+ ions formed, and cations (positive ions) will flow towards the cathode to balance the negative charge of the electrons gained by Ag+ ions.
Conclude that in this voltaic cell, anions flow from the salt bridge to the anode compartment, and cations flow from the salt bridge to the cathode compartment.

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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, also known as a 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 anode is where oxidation occurs, while the cathode is where reduction takes place, allowing for the flow of electrons through an external circuit.
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The Electrolytic Cell

Salt Bridge

The salt bridge is a crucial component of a voltaic cell that maintains electrical neutrality by allowing the flow of ions between the two half-cells. It typically contains a gel or solution of an inert electrolyte, which facilitates the movement of anions and cations. This movement helps to balance the charge as electrons flow through the external circuit, preventing the buildup of charge that would otherwise halt the reaction.
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Ionic Salts

Ion Flow Direction

In a voltaic cell, the direction of ion flow in the salt bridge is determined by the reactions occurring at the electrodes. Cations move towards the cathode to balance the negative charge created by the reduction of metal ions, while anions flow towards the anode to counteract the positive charge generated by oxidation. Understanding this flow is essential for predicting the behavior of the cell and ensuring its proper function.
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Related Practice
Textbook Question

Use line notation to represent each electrochemical cell in Problem 43.

Textbook Question

Sketch a voltaic cell for each redox reaction. Label the anode and cathode and indicate the half-reaction that occurs at each electrode and the species present in each solution. Also indicate the direction of electron flow. a. Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq)

Textbook Question

Make a sketch of the voltaic cell represented by the line notation. Write the overall balanced equation for the reaction and calculate E°cell. Sn(s) | Sn2+(aq) || NO(g) | NO3–(aq), H+(aq) | Pt(s)

Textbook Question

Calculate the standard cell potential for each of the electro- chemical cells in Problem 43.