Textbook Question
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.
(a) Does the process represent oxidation or reduction?
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Ch.20 - Electrochemistry
Chapter 20, Problem 4
Assume that you want to construct a voltaic cell that uses the following half-reactions: A2+1aq2 + 2 e- ¡ A1s2 Ered ° = -0.10 V B2+1aq2 + 2 e- ¡ B1s2 E°red = -1.10 V You begin with the incomplete cell pictured here in which the electrodes are immersed in water.
(a) What additions must you make to the cell for it to generate a standard emf?
Verified step by step guidance1
Identify the half-reactions and their standard reduction potentials: A^{2+} + 2e^- \rightarrow A (E_{red}^0 = -0.10 V) and B^{2+} + 2e^- \rightarrow B (E_{red}^0 = -1.10 V).
Determine which half-reaction will occur at the anode and which will occur at the cathode. The half-reaction with the higher reduction potential will occur at the cathode (reduction), and the one with the lower reduction potential will occur at the anode (oxidation).
Assign the electrodes: Electrode C will be the anode (oxidation of B to B^{2+}), and Electrode D will be the cathode (reduction of A^{2+} to A).
Add the appropriate solutions to each beaker: Add a solution of B^{2+} ions to the beaker with Electrode C and a solution of A^{2+} ions to the beaker with Electrode D.
Ensure the salt bridge is properly set up to allow the flow of ions between the two solutions, maintaining 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 from the anode to the cathode generates an electric current, which can be measured using a voltmeter.
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The Electrolytic Cell
Standard Electrode Potential
Standard electrode potential (E°) is a measure of the tendency of a chemical species to be reduced, measured under standard conditions (1 M concentration, 1 atm pressure, and 25°C). Each half-reaction has a specific E° value, and the overall cell potential can be calculated by subtracting the anode potential from the cathode potential. A positive cell potential indicates a spontaneous reaction.
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Salt Bridge
A salt bridge is a device used in electrochemical cells to maintain electrical neutrality by allowing the flow of ions between the two half-cells. It typically contains a gel or solution of an inert electrolyte. The salt bridge prevents the solutions in the half-cells from mixing while allowing ions to migrate, which is essential for sustaining the flow of electrons and completing the circuit.
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Related Practice
Textbook Question
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.
(b) Is the electrode the anode or cathode?
1
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Textbook Question
The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.
(c) Why are the atoms in the electrode represented by larger spheres than those in the solution? [Section 20.3]
Textbook Question
Consider the following table of standard electrode potentials for a series of hypothetical reactions in an aqueous solution: reduction half-reaction E °(V) (c) Which substance(s) can oxidize C2+?