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AP Chemistry Practice Quiz: Cell Potential Under Nonstandard Conditions

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 7 questions to check your progress.

Question 1 of 7

For a galvanic cell operating under nonstandard conditions, which principle is most often used on the AP exam to qualitatively predict the change in cell potential when reactant or product concentrations are altered?

All Questions (7)

For a galvanic cell operating under nonstandard conditions, which principle is most often used on the AP exam to qualitatively predict the change in cell potential when reactant or product concentrations are altered?

A) Hess's Law

B) Le Châtelier's Principle

C) The Aufbau Principle

D) Heisenberg's Uncertainty Principle

Correct Answer: B

According to the provided content, the relationship between species concentrations and cell potential is often assessed qualitatively using Le Châtelier's principle. Changes in concentration cause a shift in the reaction equilibrium, which in turn affects the cell's driving force (potential).

Consider a galvanic cell with the net reaction A(aq) + B(s) → C(aq) + D(s). If the concentration of the reactant A(aq) is increased from the standard 1 M, how will the cell potential, E, be affected?

A) E will increase.

B) E will decrease.

C) E will become zero.

D) E will not change from E°.

Correct Answer: A

According to Le Châtelier's principle, increasing the concentration of a reactant (A) will shift the reaction to the right, favoring the forward reaction. This increases the driving force of the reaction, resulting in a higher (more positive) cell potential, E.

A galvanic cell is constructed under standard conditions. As the cell operates, what happens to the cell potential?

A) It increases as the reaction approaches equilibrium.

B) It remains constant at E° until all reactants are consumed.

C) It decreases and eventually becomes zero when the reaction reaches equilibrium.

D) It becomes negative once the product concentrations exceed the reactant concentrations.

Correct Answer: C

As a galvanic cell operates, reactants are consumed and products are formed. This shifts the reaction toward equilibrium. The cell potential is the driving force toward equilibrium; as the reaction gets closer to equilibrium, this driving force diminishes. At equilibrium, the driving force is zero, and thus the cell potential E is 0 V.

For a spontaneous electrochemical reaction, which of the following conditions will result in a cell potential E that is less than the standard cell potential E°?

A) The reaction quotient, Q, is less than 1.

B) The reaction quotient, Q, is greater than 1.

C) The reaction quotient, Q, is equal to 1.

D) The reaction is at equilibrium.

Correct Answer: B

The Nernst equation is E = E° - (RT/nF)lnQ. When Q > 1, the concentration of products is relatively high compared to reactants (versus standard conditions). This condition shifts the reaction to the left, opposing the forward reaction and reducing the cell potential. Mathematically, if Q > 1, then ln(Q) is a positive value, and a positive term is subtracted from E°, making E < E°.

Which statement best describes the relationship between the magnitude of the cell potential and the state of the reaction?

A) The cell potential is always greatest when the reaction is at equilibrium.

B) The magnitude of the cell potential is a measure of how far the reaction is from equilibrium.

C) A small cell potential indicates that the standard cell potential, E°, must also be small.

D) The cell potential is only dependent on temperature, not on concentration.

Correct Answer: B

The provided content states that the cell potential drives the reaction toward equilibrium and that the farther the system is from equilibrium, the greater the magnitude of the cell potential. This potential represents the 'driving force' of the reaction.

Consider the galvanic cell based on the reaction: Ni(s) + 2Ag⁺(aq) → Ni²⁺(aq) + 2Ag(s). If the concentration of Ni²⁺(aq) is increased, what is the effect on the cell potential, E?

A) E will increase because the reaction shifts to the right.

B) E will decrease because the reaction shifts to the left.

C) E will not change because Ni²⁺ is a product.

D) E will become zero immediately.

Correct Answer: B

Ni²⁺ is a product of the forward reaction. According to Le Châtelier's principle, increasing the concentration of a product will cause the equilibrium to shift to the left, opposing the forward reaction. This reduces the driving force for the reaction, thereby decreasing the cell potential, E.

A galvanic cell is at equilibrium. Which of the following statements must be true?

A) The cell potential, E, is zero.

B) The standard cell potential, E°, is zero.

C) The concentrations of reactants and products are all equal to 1 M.

D) The reaction quotient, Q, is equal to zero.

Correct Answer: A

Equilibrium is the state where the forward and reverse reaction rates are equal, and there is no net change or driving force for the reaction. The cell potential is the measure of this driving force. Therefore, when a cell reaches equilibrium, its potential, E, becomes 0 V.