Question 1

Which equation correctly relates the standard cell potential ($E^	ext{cell}$), the equilibrium constant ($K$), and the number of electrons transferred ($n$) at 25°C?

Accepted Answer

$E^	ext{cell} = \frac{0.0592}{n} \log K$

Question 2

If the equilibrium constant ($K$) for a redox reaction at 25°C is $2.5 	imes 10^{18}$ and 4 electrons are transferred, what is the standard cell potential ($E^	ext{cell}$)?

Accepted Answer

$0.66\ 	ext{V}$

Question 3

Which of the following statements best describes the relationship between Gibbs Free Energy ($\Delta G$) and the standard cell potential ($E^	ext{cell}$)?

Accepted Answer

$\Delta G = -nFE^	ext{cell}$

Question 4

Given the following reduction potentials at 25°C: $	ext{Cu}^{2+} + 2e^- ightarrow 	ext{Cu}$, $E^	ext{red} = +0.34\ 	ext{V}$; $	ext{Zn}^{2+} + 2e^- ightarrow 	ext{Zn}$, $E^	ext{red} = -0.76\ 	ext{V}$. What is the standard cell potential for the reaction $	ext{Zn} + 	ext{Cu}^{2+} ightarrow 	ext{Zn}^{2+} + 	ext{Cu}$?

Accepted Answer

$1.10\ 	ext{V}$

Question 5

A cell reaction has $E^	ext{cell} = 0.00\ 	ext{V}$ at equilibrium. What is the value of the equilibrium constant $K$?

Accepted Answer

$K = 1$

Question 6

If $\Delta G$ for a reaction is negative, what can be inferred about the spontaneity and the cell potential ($E^	ext{cell}$)?

Accepted Answer

The reaction is spontaneous and $E^	ext{cell}$ is positive.

Question 7

For the reaction $2	ext{Fe}^{3+} + 2e^- ightarrow 2	ext{Fe}^{2+}$, if $E^	ext{cell} = 0.77\ 	ext{V}$ and $n = 2$, what is $\Delta G$ at 25°C? ($F = 96485\ 	ext{C/mol}$)

Accepted Answer

$-1.49 	imes 10^5\ 	ext{J}$

Question 8

Which of the following changes will increase the equilibrium constant $K$ for a redox reaction at 25°C?

Accepted Answer

Increasing the standard cell potential $E^	ext{cell}$

Question 9

A certain electrochemical reaction involves the transfer of 3 electrons and has a standard cell potential of $0.45\ 	ext{V}$ at 25°C. What is the equilibrium constant $K$ for this reaction?

Accepted Answer

$K = 1.2 	imes 10^{22}$

Question 10

Which of the following is the correct simplified formula for calculating the standard cell potential ($E^	ext{cell}$) from the equilibrium constant ($K$) at 25°C?

Accepted Answer

$E^	ext{cell} = \frac{0.0592}{n} \log K$

Question 11

If a redox reaction at 25°C has $K < 1$, what can be said about the sign of $E^	ext{cell}$?

Accepted Answer

$E^	ext{cell}$ is negative

Question 12

A battery operates based on the following reaction: $2	ext{Ag}^+ + 2e^- ightarrow 2	ext{Ag}$ ($E^	ext{red} = +0.80\ 	ext{V}$) and $	ext{Zn}^{2+} + 2e^- ightarrow 	ext{Zn}$ ($E^	ext{red} = -0.76\ 	ext{V}$). What is the standard cell potential for the battery?

Accepted Answer

$1.56\ 	ext{V}$

Question 13

Which of the following best explains why a cell with $E^	ext{cell} > 0$ will have $K > 1$?

Accepted Answer

A positive cell potential means the reaction is spontaneous and favors product formation at equilibrium.

Question 14

If the standard cell potential for a reaction is $-0.25\ 	ext{V}$ and $n = 2$, what is the value of $K$ at 25°C?

Accepted Answer

$K = 1.2 	imes 10^{-9}$

Question 15

Which of the following is NOT a correct use of the Faraday constant ($F$) in electrochemistry?

Accepted Answer

Calculating the mass of a substance produced: $m = \frac{nF}{M}$

Question 16

A medical device uses a redox reaction with $n = 2$ and $E^	ext{cell} = 0.50\ 	ext{V}$. What is the Gibbs Free Energy change ($\Delta G$) for this reaction? ($F = 96485\ 	ext{C/mol}$)

Accepted Answer

$-96,485\ 	ext{J}$

Question 17

Which of the following is the correct formula for the equilibrium constant $K$ in terms of $E^	ext{cell}$, $n$, and $T$?

Accepted Answer

$K = e^{\frac{nFE^	ext{cell}}{RT}}$

Cell Potentials, Gibbs Free Energy, and Equilibrium in Electrochemistry

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