Question 1

Which of the following statements correctly describes the role of the salt bridge in a galvanic cell?

Accepted Answer

It maintains electrical neutrality by allowing ions to flow between the half-cells.

Question 2

Given the cell notation $$\mathrm{Zn(s)\ |\ Zn$$^{2+}$$(aq,\ 1\ M)\ ||\ Cu$$^{2+}$$(aq,\ 1\ M)\ |\ Cu(s)}$$, which species is oxidized and which is reduced?

Accepted Answer

Cu is reduced; Zn is oxidized.

Question 3

What is the standard cell potential ($$E^\circ_{cell}) $$for the reaction $$\mathrm{Cu$$^{2+}$$(aq) + Zn(s) \rightarrow Cu(s) + Zn$$^{2+}$$(aq)}$$ given $$E^\circ (\mathrm{Cu$$^{2+}$$/Cu}) = 0.34\ V$$ and $$E^\circ (\mathrm{Zn$$^{2+}$$/Zn}) = -0.76\ V$$?

Accepted Answer

$$E^\circ_{cell} = 0.34\ V - (-0.76\ V) = 1.10\ V$$

Question 4

Which of the following best describes the function of an inert electrode (such as Pt) in an electrochemical cell?

Accepted Answer

It provides a surface for electron transfer when no solid metal is present.

Question 5

A student sets up a galvanic cell with the following half-reactions:
$$\mathrm{Ag^+(aq) + e^- \rightarrow Ag(s)}$$ ($$E^\circ = 0.80\ V$$)
$$\mathrm{Fe$$^{2+}$$(aq) \rightarrow Fe$$^{3+}$$(aq) + e^-}$$ ($$E^\circ = 0.77\ V)
$$What is the standard cell potential ($$E^\circ_{cell}$$)?

Accepted Answer

$$E^\circ_{cell} = 0.80\ V - 0.77\ V = 0.03\ V$$

Question 6

Which of the following changes will increase the cell potential ($$E_{cell}) $$for a galvanic cell based on the Nernst equation?

Accepted Answer

Increasing the concentration of reactants.

Question 7

For the reaction $$\mathrm{2H_2O(l) \rightarrow 2H_2(g) + O_2$(g)} in an $$electrolytic cell, which statement is correct?

Accepted Answer

The reaction is nonspontaneous and requires an external power source.

Question 8

Which of the following is the correct relationship between Gibbs free energy and cell potential at standard conditions?

Accepted Answer

$$\Delta G^\circ = -nFE^\circ$$

Question 9

A redox reaction has $$\Delta G^\circ  0. $$What does this indicate about the reaction?

Accepted Answer

The reaction is spontaneous.

Question 10

Which of the following is the correct Nernst equation for a cell at non-standard conditions?

Accepted Answer

$$E = E^\circ - (RT/nF) \ln(Q)$$

Question 11

In the cell notation $$\mathrm{Zn(s)\ |\ Zn$$^{2+}$$(aq)\ ||\ Cu$$^{2+}$$(aq)\ |\ Cu(s)}$$, what is the direction of electron flow?

Accepted Answer

From Zn to Cu through the wire.

Question 12

Which of the following best describes the anode in a galvanic cell?

Accepted Answer

It is where oxidation occurs and is negative.

Question 13

A student is balancing the following redox reaction in acidic solution:
$$\mathrm{$$MnO_4$$^-(aq) + Fe$$^{2+}$$(aq) \rightarrow Mn$$^{2+}$$(aq) + Fe$$^{3+}$$(aq)}$$
Which is the correct sequence for balancing the half-reactions?

Accepted Answer

Balance all atoms except H and O, then O with $$\mathrm{H_2O}$$, H with $$\mathrm{H^+}$$, then electrons.

Question 14

Which of the following statements about oxidation numbers is correct?

Accepted Answer

Hydrogen has an oxidation number of $$-1$$ when bonded to a metal.

Question 15

If the equilibrium constant $$K$$ for a redox reaction is much greater than 1, what can you conclude about $$E^\circ_{cell}$$?

Accepted Answer

$$E^\circ_{cell} is $$positive.

Question 16

Which of the following is the correct expression for the reaction quotient $$Q in $$the Nernst equation for the cell reaction $$\mathrm{Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)}$$?

Accepted Answer

$$Q = \dfrac{[Zn$$^{2+}$$]}{[Cu$$^{2+}$$]}$$

Question 17

A battery is constructed using the reaction $$\mathrm{2Al(s) + 3Cu$$^{2+}$$(aq) \rightarrow 2Al$$^{3+}$$(aq) + 3Cu(s)}. If$$ $$n is $$the number of electrons transferred, what is the value of $$n$$?

Accepted Answer

$$n = 6$$

Question 18

Which of the following would make a redox reaction more product-favored under non-standard conditions?

Accepted Answer

Decreasing the concentration of products.

Question 19

In a galvanic cell, which of the following statements is true about the movement of ions?

Accepted Answer

Cations move toward the cathode and anions move toward the anode.

Electrochemistry: Principles, Calculations, and Applications

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