Question 1

Which of the following statements best describes the role of the oxidizing agent in a redox reaction?

Accepted Answer

It accepts electrons from another species, causing that species to be oxidized.

Question 2

What is the oxidation number of sulfur in $$\mathrm{SO_2$}$$?

Accepted Answer

$$+4$$

Question 3

Which of the following is the correct balanced half-reaction for the reduction of $$\mathrm{$$MnO_4$$^-} to$$ $$\mathrm{Mn$$^{2+}$$} in $$acidic solution?

Accepted Answer

$$\mathrm{$$MnO_4$$^-} + 8\ H^+ + 5\ e^- \rightarrow Mn$$^{2+}$$ + 4\ H_2O$$

Question 4

In the reaction $$2\ Na(s) + Cl_2$(g) \rightarrow 2\ NaCl(s)$$, which species is oxidized and which is reduced?

Accepted Answer

Na is oxidized, Cl is reduced.

Question 5

Which of the following rules is INCORRECT for assigning oxidation numbers?

Accepted Answer

The oxidation state of oxygen is always $$-2.$$

Question 6

Which step is unique to balancing redox reactions in BASIC solution compared to ACIDIC solution?

Accepted Answer

Adding $$OH^- to $$both sides to neutralize $$H^+$$ and form water.

Question 7

In a voltaic cell, which of the following statements is TRUE?

Accepted Answer

Oxidation occurs at the anode and reduction occurs at the cathode.

Question 8

A voltaic cell is constructed using zinc and copper electrodes. Which reaction occurs at the cathode?

Accepted Answer

$$\mathrm{Cu$$^{2+}$$ + 2\ e^- \rightarrow Cu(s)}$$

Question 9

Why is a salt bridge necessary in a voltaic cell?

Accepted Answer

To maintain electrical neutrality by allowing ion flow between compartments.

Question 10

Given the cell notation $$\mathrm{Zn(s) | Zn$$^{2+}$$(aq) || Cu$$^{2+}$$(aq) | Cu(s)}$$, which of the following is correct?

Accepted Answer

Zinc is the anode and copper is the cathode.

Question 11

Which of the following best explains why electrons flow spontaneously from the anode to the cathode in a voltaic cell?

Accepted Answer

The anode has higher electrical potential energy than the cathode.

Question 12

Which of the following is the correct cell notation for the reaction $$2\ Tl(s) + Sn$$^{2+}$$(aq) \rightarrow 2\ Tl^+(aq) + Sn(s)$$?

Accepted Answer

$$\mathrm{Tl(s) | Tl^+(aq) || Sn$$^{2+}$$(aq) | Sn(s)}$$

Question 13

In the reaction $$\mathrm{Cr_2O_7$$^{2-}$$ + 6\ Fe$$^{2+}$$ + 14\ H^+ \rightarrow 2\ Cr$$^{3+}$$ + 6\ Fe$$^{3+}$$ + 7\ H_2O}$$, what is the reducing agent?

Accepted Answer

$$\mathrm{Fe$$^{2+}$$}$$

Question 14

Which of the following is a correct step when balancing a redox reaction in acidic solution?

Accepted Answer

Balance oxygen atoms by adding $$H_2O.$$

Question 15

A student is asked to balance the following redox reaction in basic solution: $$\mathrm{NO_2$^- (aq) + Al(s) \rightarrow $$AlO_2$$^- (aq) + NH_3$(g)}. $$Which step should be performed after balancing the reaction as if it were in acidic solution?

Accepted Answer

Add $$OH^- to $$both sides to neutralize $$H^+.$$

Question 16

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

Accepted Answer

It allows the flow of ions to maintain electrical neutrality.

Question 17

In the voltaic cell described by $$\mathrm{Zn(s) | Zn$$^{2+}$$(aq) || Cu$$^{2+}$$(aq) | Cu(s)}$$, what would happen if the salt bridge were removed?

Accepted Answer

The cell would stop functioning due to charge buildup.

Electrochemistry: Redox Reactions and Voltaic Cells (General Chemistry II, Chapter 18)

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