AP Chemistry Flashcards: Cell Potential And Free Energy

What this deck covers

This deck focuses on Cell Potential And Free Energy, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is Faraday's constant value?

Answer: $96485 \text{ C/mol}$. Conversion factor between moles of electrons and electric charge.

Flashcard 2: Why is the standard hydrogen electrode used as a reference?

Answer: Assigned a potential of 0.00 V. Provides a universal standard for comparing electrode potentials.

Flashcard 3: Identify the formula for the change in Gibbs free energy, $\triangle G$, in terms of $E$.

Answer: $\triangle G = -nFE$. Direct relationship between free energy change and electrochemical potential.

Flashcard 4: What is the effect of a catalyst on cell potential?

Answer: No effect on cell potential. Catalysts affect reaction rate but not thermodynamic quantities.

Flashcard 5: Calculate $\triangle G$ for a cell with $n=2$, $F=96485 \text{ C/mol}$, and $E=1.5 \text{ V}$.

Answer: $\triangle G = -289455 \text{ J/mol}$. Using $\triangle G = -nFE$ with given values: $-(2)(96485)(1.5)$.

Flashcard 6: Determine the spontaneity: $E^0_\text{cell} = -0.76 \text{ V}$.

Answer: Non-spontaneous reaction. Negative standard cell potential indicates $\triangle G^0 > 0$, non-spontaneous.

Flashcard 7: State the condition under which $E^0_\text{cell} = 0$.

Answer: Equilibrium is established. Zero cell potential means no driving force for electron flow.

Flashcard 8: Find the cell potential with $E^0_\text{cell} = 0.44 \text{ V}$ and $Q = 10$ at $298 \text{ K}$.

Answer: $E < 0.44 \text{ V}$. Nernst equation shows $E$ decreases when $Q > 1$ compared to $E^0$.

Flashcard 9: What is the effect of increasing reactant concentration on cell potential?

Answer: Increases cell potential. Higher reactant concentration makes $Q$ smaller, increasing $E$.

Flashcard 10: Identify the temperature used for standard conditions in electrochemistry.

Answer: $298 \text{ K}$. Standard temperature for electrochemical measurements (25°C).

Flashcard 11: Determine the effect on $E$ when product concentration increases.

Answer: Decreases cell potential. Higher product concentration increases $Q$, reducing cell potential.

Flashcard 12: What is the relationship between $\triangle G^0$ and reaction spontaneity?

Answer: $\triangle G^0 < 0$ indicates spontaneity. Negative standard free energy indicates spontaneous process under standard conditions.

Flashcard 13: What is the concentration of ions in a standard solution?

Answer: $1 \text{ M}$. Standard concentration for aqueous ionic solutions in electrochemistry.

Flashcard 14: What is the standard cell potential for a galvanic cell?

Answer: The cell potential under standard conditions. Measured when all species are at standard conditions (1 M, 1 atm, 25°C).

Flashcard 15: Determine the spontaneity: $\triangle G = 0$.

Answer: Reaction is at equilibrium. Zero free energy change indicates no net driving force for reaction.

Flashcard 16: What is the direction of electron flow in a galvanic cell?

Answer: From anode to cathode. Electrons move from negative anode to positive cathode through external circuit.

Flashcard 17: Calculate $\triangle G$ for a cell with $n=2$, $F=96485 \text{ C/mol}$, and $E=1.5 \text{ V}$.

Answer: $\triangle G = -289455 \text{ J/mol}$. Using $\triangle G = -nFE$ with given values: $-(2)(96485)(1.5)$.

Flashcard 18: State the unit of cell potential.

Answer: Volts (V). Standard SI unit for electric potential difference.

Flashcard 19: Calculate the cell potential given $E^0_\text{cell} = 1.10 \text{ V}$ and $Q = 1.0$ at $298 \text{ K}$.

Answer: $E = E^0_\text{cell} = 1.10 \text{ V}$. When $Q = 1$, the Nernst equation reduces to $E = E^0$.

Flashcard 20: What does a zero cell potential mean in a galvanic cell?

Answer: The cell is at equilibrium. No potential difference means equilibrium between electrodes.

Flashcard 21: What does a negative $\triangle G$ indicate about a reaction?

Answer: The reaction is spontaneous. Negative free energy change indicates thermodynamically favorable process.

Flashcard 22: What does a negative cell potential indicate about a reaction's spontaneity?

Answer: The reaction is non-spontaneous. Negative $E$ means $\triangle G > 0$, thermodynamically unfavorable.

Flashcard 23: Calculate $E$ for $E^0_\text{cell} = 1.10 \text{ V}$, $T = 298 \text{ K}$, $n=2$, $Q=0.1$.

Answer: $E > 1.10 \text{ V}$. When $Q < 1$, the Nernst equation predicts $E > E^0$.

Flashcard 24: What is the $\triangle G^0$ for a reaction at equilibrium?

Answer: $\triangle G^0 = 0$. At equilibrium, forward and reverse reactions have equal rates.

Flashcard 25: What is the standard cell potential for a galvanic cell?

Answer: The cell potential under standard conditions. Measured when all species are at standard conditions (1 M, 1 atm, 25°C).

Flashcard 26: State the Nernst equation for electrochemical cells.

Answer: $E = E^0 - \frac{RT}{nF} \times \text{ln}Q$. Relates cell potential to standard potential and reaction quotient.

Flashcard 27: What is the standard reduction potential of a hydrogen electrode?

Answer: 0.00 V. Serves as the reference point for measuring all other electrode potentials.

Flashcard 28: Identify the temperature used for standard conditions in electrochemistry.

Answer: $298 \text{ K}$. Standard temperature for electrochemical measurements (25°C).

Flashcard 29: What is Faraday's constant value?

Answer: $96485 \text{ C/mol}$. Conversion factor between moles of electrons and electric charge.

Flashcard 30: State the relationship between $K_{eq}$ and $E^0_\text{cell}$.

Answer: $E^0_\text{cell} = \frac{RT}{nF} \times \ln K_{eq}$. Equilibrium constant relates to standard cell potential through thermodynamics.

Flashcard 31: Which factor affects cell potential according to the Nernst equation?

Answer: Concentration of reactants and products. The reaction quotient $Q$ in the Nernst equation depends on species concentrations.

Flashcard 32: Calculate $\triangle G^0$ given $n=3$, $F=96485 \text{ C/mol}$, $E^0_\text{cell}=1.2 \text{ V}$.

Answer: $\triangle G^0 = -347346 \text{ J/mol}$. Using $\triangle G^0 = -nFE^0$ with given values: $-(3)(96485)(1.2)$.

Flashcard 33: Calculate the cell potential given $E^0_\text{cell} = 1.10 \text{ V}$ and $Q = 1.0$ at $298 \text{ K}$.

Answer: $E = E^0_\text{cell} = 1.10 \text{ V}$. When $Q = 1$, the Nernst equation reduces to $E = E^0$.

Flashcard 34: Determine the spontaneity: $E^0_\text{cell} = -0.76 \text{ V}$.

Answer: Non-spontaneous reaction. Negative standard cell potential indicates $\triangle G^0 > 0$, non-spontaneous.

Flashcard 35: Identify the relationship between free energy and cell potential.

Answer: $\triangle G = -nFE$. Shows Gibbs free energy is proportional to cell potential times electrons and Faraday's constant.

Flashcard 36: Calculate the equilibrium constant, $K_{eq}$, for $E^0_\text{cell} = 0.0592 \text{ V}$ at $298 \text{ K}$.

Answer: $K_{eq} \text{ is large (spontaneous)}$. Positive $E^0$ indicates large equilibrium constant favoring products.

Flashcard 37: What is the standard condition for pressure in electrochemistry?

Answer: 1 atm. Standard atmospheric pressure for electrochemical measurements.

Flashcard 38: Why is the standard hydrogen electrode used as a reference?

Answer: Assigned a potential of 0.00 V. Provides a universal standard for comparing electrode potentials.

Flashcard 39: What is the equation for standard free energy change, $\triangle G^0$?

Answer: $\triangle G^0 = -nFE^0_\text{cell}$. Standard free energy relates to standard cell potential through Faraday's constant.

Flashcard 40: What is the effect of a catalyst on cell potential?

Answer: No effect on cell potential. Catalysts affect reaction rate but not thermodynamic quantities.

Flashcard 41: What is the equation for standard free energy change, $\triangle G^0$?

Answer: $\triangle G^0 = -nFE^0_\text{cell}$. Standard free energy relates to standard cell potential through Faraday's constant.

Flashcard 42: Find the cell potential with $E^0_\text{cell} = 0.44 \text{ V}$ and $Q = 10$ at $298 \text{ K}$.

Answer: $E < 0.44 \text{ V}$. Nernst equation shows $E$ decreases when $Q > 1$ compared to $E^0$.

Flashcard 43: State the Nernst equation for electrochemical cells.

Answer: $E = E^0 - \frac{RT}{nF} \times \text{ln}Q$. Relates cell potential to standard potential and reaction quotient.

Flashcard 44: What is the effect of increasing reactant concentration on cell potential?

Answer: Increases cell potential. Higher reactant concentration makes $Q$ smaller, increasing $E$.

Flashcard 45: Calculate $E$ for $E^0_\text{cell} = 1.10 \text{ V}$, $T = 298 \text{ K}$, $n=2$, $Q=0.1$.

Answer: $E > 1.10 \text{ V}$. When $Q < 1$, the Nernst equation predicts $E > E^0$.

Flashcard 46: Calculate $\triangle G^0$ given $n=3$, $F=96485 \text{ C/mol}$, $E^0_\text{cell}=1.2 \text{ V}$.

Answer: $\triangle G^0 = -347346 \text{ J/mol}$. Using $\triangle G^0 = -nFE^0$ with given values: $-(3)(96485)(1.2)$.

Flashcard 47: Identify the relationship between free energy and cell potential.

Answer: $\Delta G = -nFE$. Shows Gibbs free energy is proportional to cell potential times electrons and Faraday's constant.

Flashcard 48: State the relationship between $E^0_\text{cell}$ and $\triangle G^0$ for spontaneous reactions.

Answer: $E^0_\text{cell} > 0, \triangle G^0 < 0$. Spontaneous reactions have positive cell potential and negative free energy.

Flashcard 49: What is the role of the salt bridge in a galvanic cell?

Answer: To maintain electrical neutrality. Allows ion migration to balance charge buildup at electrodes.

Flashcard 50: What does a positive cell potential indicate about a reaction's spontaneity?

Answer: The reaction is spontaneous. Positive $E$ means $\triangle G < 0$, indicating thermodynamic favorability.

Flashcard 51: Identify the formula for the change in Gibbs free energy, $\triangle G$, in terms of $E$.

Answer: $\triangle G = -nFE$. Direct relationship between free energy change and electrochemical potential.

Flashcard 52: How does temperature affect cell potential?

Answer: Alters $E$ via the Nernst equation. Temperature appears in the $RT/nF$ term of the Nernst equation.

Flashcard 53: What is the formula for the equilibrium constant in terms of $\triangle G^0$?

Answer: $\triangle G^0 = -RT \times \text{ln}K_{eq}$. Connects equilibrium constant to standard free energy change.

Flashcard 54: What is the standard reduction potential of a hydrogen electrode?

Answer: 0.00 V. Serves as the reference point for measuring all other electrode potentials.

Flashcard 55: State the condition under which $E^0_\text{cell} = 0$.

Answer: Equilibrium is established. Zero cell potential means no driving force for electron flow.

Flashcard 56: Calculate the equilibrium constant, $K_{eq}$, for $E^0_\text{cell} = 0.0592 \text{ V}$ at $298 \text{ K}$.

Answer: $K_{eq} \text{ is large (spontaneous)}$. Positive $E^0$ indicates large equilibrium constant favoring products.

Flashcard 57: What is the role of the salt bridge in a galvanic cell?

Answer: To maintain electrical neutrality. Allows ion migration to balance charge buildup at electrodes.

Flashcard 58: What does a positive cell potential indicate about a reaction's spontaneity?

Answer: The reaction is spontaneous. Positive $E$ means $\triangle G < 0$, indicating thermodynamic favorability.

Flashcard 59: What is the primary purpose of the Nernst equation?

Answer: To calculate cell potential under non-standard conditions. Adjusts standard cell potential for actual concentration and temperature conditions.

Flashcard 60: Determine the spontaneity: $\triangle G = 0$.

Answer: Reaction is at equilibrium. Zero free energy change indicates no net driving force for reaction.

Flashcard 61: What is the standard reduction potential of a hydrogen electrode?

Answer: 0.00 V. Serves as the reference point for measuring all other electrode potentials.