Multiple Choice
In an electrochemical cell, if the Gibbs free energy change (ΔG) is positive, what can be said about the cell potential (E°cell)?
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20. Electrochemistry
Cell Potential and Gibbs Free Energy
Multiple Choice
What is ΔG° (in kJ/mol) for a redox reaction where two electrons are transferred with E°_cell = -0.273 V?
A
-52.6 kJ/mol
B
-26.3 kJ/mol
C
26.3 kJ/mol
D
52.6 kJ/mol
Verified step by step guidance1
Identify the formula to calculate the standard Gibbs free energy change (ΔG°) for a redox reaction: ΔG° = -nFE°_cell, where n is the number of moles of electrons transferred, F is the Faraday constant (approximately 96485 C/mol), and E°_cell is the standard cell potential.
Determine the number of moles of electrons transferred in the reaction. In this problem, n = 2 electrons.
Substitute the given values into the formula: n = 2, F = 96485 C/mol, and E°_cell = -0.273 V.
Calculate the product of n, F, and E°_cell. Remember that the units of F (C/mol) and E°_cell (V) will result in the energy being in joules per mole (J/mol).
Convert the energy from joules per mole to kilojoules per mole (kJ/mol) by dividing the result by 1000.
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