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

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Understand that a voltaic cell, also known as a galvanic cell, is an electrochemical cell that derives electrical energy from spontaneous redox reactions occurring within the cell.

Recall that the cell potential (also known as electromotive force, EMF) is the measure of the voltage difference between the two electrodes of the cell.

Recognize that for a voltaic cell to function, the redox reaction must be spontaneous, which means the Gibbs free energy change (ΔG) is negative.

Use the relationship between Gibbs free energy and cell potential: ΔG = -nFE, where n is the number of moles of electrons transferred, F is Faraday's constant, and E is the cell potential.

Conclude that since ΔG is negative for spontaneous reactions, the cell potential (E) must be positive for all functioning voltaic cells, as a positive E ensures a negative ΔG.

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Key Concepts

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

Voltaic Cells

Voltaic cells, also known as galvanic cells, are electrochemical cells that convert chemical energy into electrical energy through spontaneous redox reactions. In these cells, oxidation occurs at the anode and reduction at the cathode, generating a flow of electrons that can be harnessed for electrical work. Understanding the structure and function of voltaic cells is essential for analyzing their cell potential.

Cell Potential

Cell potential, or electromotive force (EMF), is the measure of the voltage generated by a voltaic cell when it is operating under standard conditions. It is determined by the difference in reduction potentials of the half-reactions occurring at the anode and cathode. A positive cell potential indicates that the reaction is spontaneous, while a negative value suggests non-spontaneity.

Standard Reduction Potentials

Standard reduction potentials are tabulated values that represent the tendency of a species to gain electrons and be reduced, measured under standard conditions. Each half-reaction has a specific potential, and the overall cell potential is calculated by subtracting the anode potential from the cathode potential. This concept is crucial for predicting whether a voltaic cell will produce a positive cell potential.