AP Chemistry Flashcards: Cell Potential and Free Energy
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
What does electrochemistry study?
Electrochemistry is the field that studies redox reactions occurring within electrochemical cells.
Card 1 of 10
All Flashcards (10)
What does electrochemistry study?
Electrochemistry is the field that studies redox reactions occurring within electrochemical cells.
How can you determine if an electrochemical cell's reaction is thermodynamically favored using its standard cell potential (E°)?
A reaction is thermodynamically favored if it has a positive standard cell potential (E°). A negative E° indicates an unfavored reaction.
Explain the significance of a negative ΔG° in an electrochemical cell.
A negative standard Gibbs free energy change (ΔG°) signifies that a reaction is thermodynamically favored, which corresponds to a positive cell potential (E°).
If a cell has a positive standard cell potential (E°), what is the sign of its standard Gibbs free energy change (ΔG°)?
If the standard cell potential (E°) is positive, the standard Gibbs free energy change (ΔG°) will be negative, indicating a thermodynamically favored reaction.
A student calculates a standard cell potential of -0.45 V. What does this value imply about the reaction's spontaneity and its ΔG°?
This implies the reaction is thermodynamically unfavored (non-spontaneous) and will have a positive standard Gibbs free energy change (ΔG°).
What is required for a reaction with a negative cell potential to occur?
A reaction with a negative voltage is thermodynamically unfavored and requires the application of an external potential to proceed.
What is the relationship between standard Gibbs free energy change (ΔG°) and standard cell potential (E°)?
The standard Gibbs free energy change is proportional to the negative of the standard cell potential, as described by the equation ΔG° = −nFE°.
How is the overall standard cell potential calculated?
The standard cell potential is calculated by identifying the oxidation and reduction half-reactions and their corresponding standard reduction potentials.
What is a thermodynamically unfavored reaction in electrochemistry?
A thermodynamically unfavored reaction is one that has a negative voltage (E°) and a positive Gibbs free energy change (ΔG°).
An electrochemical cell is constructed and found to have a ΔG° of +87 kJ/mol. Is this reaction thermodynamically favored?
No, the reaction is not thermodynamically favored because a positive ΔG° corresponds to a negative cell potential (E°).