Q: Given the following half-reactions and their standard reduction potentials: $\text{Ni}^{2+}(aq) + 2e^- \rightarrow \text{Ni}(s)$ $E^ ext{o} = -0.23\,\text{V}$ $\text{Al}^{3+}(aq) + 3e^- \rightarrow \text{Al}(s)$ $E^ ext{o} = -1.66\,\text{V}$ What is the standard cell potential ($E^ ext{o}_\text{cell}$) for the reaction: $3\text{Ni}^{2+}(aq) + 2\text{Al}(s) \rightarrow 3\text{Ni}(s) + 2\text{Al}^{3+}(aq)$?

$E^ ext{o}_\text{cell} = +1.43\,\text{V}$

Q: Using the Nernst equation, calculate the cell potential for the following reaction at $25^\circ$C when $[\text{Cu}^{2+}] = 2.0\,\text{M}$ and $[\text{Zn}^{2+}] = 0.010\,\text{M}$: $\text{Cu}^{2+}(aq) + \text{Zn}(s) \rightarrow \text{Cu}(s) + \text{Zn}^{2+}(aq)$ Given $E^ ext{o}_\text{cell} = 1.10\,\text{V}$.

$E_\text{cell} = 1.10 + 0.0592 \log \left( \frac{0.010}{2.0} \right)$

Q: Which equation correctly relates the standard free energy change to the standard cell potential?

$\Delta G^\text{o} = -nFE^\text{o}_\text{cell}$

Q: Which of the following is true for a cell where $Q = 0.0010$ and $K = 0.10$?

$E_\text{cell}$ is positive and $E^\text{o}_\text{cell}$ is negative

Q: Which equation is used to calculate the equilibrium constant $K$ from the standard cell potential $E^\text{o}_\text{cell}$?

$E^\text{o}_\text{cell} = \frac{0.0592}{n} \log K$

Q: For the reaction $\text{Zn}(s) + 2\text{H}^+(aq) \rightarrow \text{Zn}^{2+}(aq) + \text{H}_2(g)$, what is the standard cell potential if the standard hydrogen electrode (SHE) is used as the cathode?

$E^\text{o}_\text{cell} = -0.76\,\text{V}$

Question 1

Which of the following statements correctly describes the relationship between $E^	ext{o}_	ext{cell}$, $\Delta G^	ext{o}$, and $K$ for a spontaneous electrochemical reaction under standard conditions?

Accepted Answer

$E^	ext{o}_	ext{cell} > 0$, $\Delta G^	ext{o} < 0$, $K > 1$

Question 2

Given the following half-reactions and their standard reduction potentials:

$	ext{Ni}^{2+}(aq) + 2e^- ightarrow 	ext{Ni}(s)$  $E^	ext{o} = -0.23\,	ext{V}$
$	ext{Al}^{3+}(aq) + 3e^- ightarrow 	ext{Al}(s)$  $E^	ext{o} = -1.66\,	ext{V}$

What is the standard cell potential ($E^	ext{o}_	ext{cell}$) for the reaction:

$3	ext{Ni}^{2+}(aq) + 2	ext{Al}(s) ightarrow 3	ext{Ni}(s) + 2	ext{Al}^{3+}(aq)$?

Accepted Answer

$E^	ext{o}_	ext{cell} = +1.43\,	ext{V}$

Question 3

Using the Nernst equation, calculate the cell potential for the following reaction at $25^\circ$C when $[	ext{Cu}^{2+}] = 2.0\,	ext{M}$ and $[	ext{Zn}^{2+}] = 0.010\,	ext{M}$:

$	ext{Cu}^{2+}(aq) + 	ext{Zn}(s) ightarrow 	ext{Cu}(s) + 	ext{Zn}^{2+}(aq)$

Given $E^	ext{o}_	ext{cell} = 1.10\,	ext{V}$.

Accepted Answer

$E_	ext{cell} = 1.10 + 0.0592 \log \left( \frac{0.010}{2.0} ight)$

Question 4

A voltaic cell is constructed using the following half-cells:

$	ext{Ag}^{+}(aq) + e^- ightarrow 	ext{Ag}(s)$  $E^	ext{o} = +0.80\,	ext{V}$
$	ext{Au}^{3+}(aq) + 3e^- ightarrow 	ext{Au}(s)$  $E^	ext{o} = +1.50\,	ext{V}$

Which metal acts as the anode?

Accepted Answer

Silver (Ag)

Question 5

For the reaction $3	ext{Ni}^{2+}(aq) + 2	ext{Al}(s) ightarrow 3	ext{Ni}(s) + 2	ext{Al}^{3+}(aq)$, how much work (in kJ) can be obtained if $E^	ext{o}_	ext{cell} = 1.43\,	ext{V}$ and $n = 6$? Use $F = 96,485\,	ext{C/mol}$.

Accepted Answer

$-830\,	ext{kJ}$

Question 6

Which equation correctly relates the standard free energy change to the standard cell potential?

Accepted Answer

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

Question 7

A concentration cell is set up with $[	ext{Cu}^{2+}] = 1.0\,	ext{M}$ in one half-cell and $[	ext{Cu}^{2+}] = 0.10\,	ext{M}$ in the other. What is the direction of electron flow?

Accepted Answer

From the 0.10 M cell to the 1.0 M cell

Question 8

Which of the following is true for a cell where $Q = 0.0010$ and $K = 0.10$?

Accepted Answer

$E_	ext{cell}$ is positive and $E^	ext{o}_	ext{cell}$ is negative

Question 9

In a redox reaction, which species is oxidized?

Accepted Answer

The species that loses electrons

Question 10

Which equation is used to calculate the equilibrium constant $K$ from the standard cell potential $E^	ext{o}_	ext{cell}$?

Accepted Answer

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

Question 11

For the reaction $	ext{Zn}(s) + 2	ext{H}^+(aq) ightarrow 	ext{Zn}^{2+}(aq) + 	ext{H}_2(g)$, what is the standard cell potential if the standard hydrogen electrode (SHE) is used as the cathode?

Accepted Answer

$E^	ext{o}_	ext{cell} = -0.76\,	ext{V}$

Question 12

Which of the following best describes the function of a salt bridge in a voltaic cell?

Accepted Answer

It maintains electrical neutrality by allowing ion flow

Question 13

A neuron transmits signals via changes in membrane potential. Which equation is used to calculate the membrane potential due to potassium ion concentration differences?

Accepted Answer

$E = E^	ext{o} - \frac{RT}{nF} \ln \left( \frac{[K^+]_{	ext{inside}}}{[K^+]_{	ext{outside}}} ight)$

Question 14

Which of the following is true for a reaction with $E^	ext{o}_	ext{cell} < 0$?

Accepted Answer

The equilibrium constant $K < 1$

Question 15

For the cell $	ext{Cd}(s) | 	ext{Cd}^{2+}(aq, 0.60\,	ext{M}) || 	ext{Fe}^{2+}(aq, 0.010\,	ext{M}) | 	ext{Fe}(s)$, calculate the cell potential using the Nernst equation. Given $E^	ext{o}_	ext{cell} = -0.04\,	ext{V}$ and $n = 2$.

Accepted Answer

$E_	ext{cell} = -0.04 + \frac{0.0592}{2} \log \left( \frac{0.010}{0.60} ight)$

Question 16

Which of the following is the correct cell notation for a voltaic cell constructed from $	ext{Ag}^{+}(aq)$ and $	ext{Au}^{3+}(aq)$ half-cells?

Accepted Answer

$	ext{Ag}(s) | 	ext{Ag}^{+}(aq, 1.0\,	ext{M}) || 	ext{Au}^{3+}(aq, 1.0\,	ext{M}) | 	ext{Au}(s)$

Question 17

What is the equilibrium constant $K$ for the redox reaction between $	ext{Al}(s)$ and $	ext{Ni}^{2+}(aq)$, given $E^	ext{o}_	ext{cell} = 1.43\,	ext{V}$ and $n = 6$?

Accepted Answer

$K = 10^{14}$

Question 18

Which of the following best describes a concentration cell?

Accepted Answer

A cell in which voltage is generated because of differences in concentrations

Electrochemistry: Cell Potentials, Redox Reactions, and Equilibrium (Chapter 19 Study Notes)

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