Multiple Choice
What is ΔG° (in kJ/mol) for a redox reaction where two electrons are transferred with E°_cell = -0.273 V?
795
views
20. Electrochemistry
Cell Potential and Gibbs Free Energy
Multiple Choice
What is the gibbs free energy change for the given reaction at 25ºC?
Au3+ (aq) + 3 Li (s) →. Au (s) + 3 Li+ (aq)
Given the following reduction potentials:
Au3+(aq) + 3 e– →. Au (s) E°red = + 1.50 Volts
Li+ (aq) + e– →. Li (s) E°red = – 3.04 Volts
A
+1314 kJ
B
-131.4 kJ
C
-1314 kJ
D
+109.5 kJ
Verified step by step guidance1
Identify the half-reactions involved in the given redox reaction. The reduction half-reaction is Au3+(aq) + 3 e– → Au(s) with E°red = +1.50 V, and the oxidation half-reaction is Li(s) → Li+(aq) + e–, which is the reverse of the given reduction potential for Li+.
Calculate the standard cell potential (E°cell) for the overall reaction. This is done by subtracting the standard reduction potential of the oxidation half-reaction from the standard reduction potential of the reduction half-reaction: E°cell = E°red (Au3+/Au) - E°red (Li+/Li).
Use the Nernst equation to relate the Gibbs free energy change (ΔG°) to the standard cell potential: ΔG° = -nFE°cell, where n is the number of moles of electrons transferred in the balanced equation (n = 3 for this reaction), and F is the Faraday constant (approximately 96485 C/mol).
Substitute the values of n, F, and E°cell into the equation to calculate ΔG° in joules. Remember to convert the final answer into kilojoules by dividing by 1000.
Interpret the sign of ΔG° to determine the spontaneity of the reaction. A negative ΔG° indicates that the reaction is spontaneous under standard conditions.
Related Videos
Related Practice
