Question 1

Which statement best describes the fundamental difference between oxidation and reduction in a chemical reaction?

Accepted Answer

Oxidation is the loss of electrons, while reduction is the gain of electrons.

Question 2

In the hydrogen–oxygen fuel cell, which element acts as the reducing agent and why?

Accepted Answer

Hydrogen, because it loses electrons to oxygen.

Question 3

Which of the following is the correct mnemonic for remembering oxidation and reduction?

Accepted Answer

OIL RIG—Oxidation Is Loss (of electrons); Reduction Is Gain (of electrons)

Question 4

Assign the oxidation state to each atom in $$\mathrm{H_2O}$$ and identify which element is more electronegative.

Accepted Answer

Hydrogen: $$+1$$, Oxygen: $$-2$$; Oxygen is more electronegative.

Question 5

Which metal would be most suitable as a sacrificial anode to protect iron from corrosion, based on the activity series?

Accepted Answer

Zinc

Question 6

A redox reaction occurs in acidic solution. Which step must be included when balancing the half-reactions?

Accepted Answer

Balance oxygen by adding $$\mathrm{H_2O}$$ and hydrogen by adding $$\mathrm{H^+}.$$

Question 7

Which of the following reactions is spontaneous according to the activity series?

Accepted Answer

$$\mathrm{Mg(s) + Cu$$^{2+}$$(aq) \rightarrow Mg$$^{2+}$$(aq) + Cu(s)}$$

Question 8

In a voltaic cell, which direction do electrons flow?

Accepted Answer

From the anode to the cathode

Question 9

Which process is used to produce hydrogen for fuel cells using renewable energy sources?

Accepted Answer

Electrolysis of water

Question 10

What is the main environmental advantage of hydrogen–oxygen fuel cell vehicles?

Accepted Answer

They emit only water as a byproduct.

Question 11

Which of the following statements about corrosion is correct?

Accepted Answer

Corrosion is the oxidation of metals, commonly iron, by atmospheric oxygen.

Question 12

Which battery type is composed of a zinc case as the anode and a graphite rod as the cathode?

Accepted Answer

Dry-cell battery

Question 13

In the process of electrolysis, what is the role of electrical current?

Accepted Answer

It drives a nonspontaneous redox reaction.

Question 14

Which element is oxidized and which is reduced in the following reaction: $$\mathrm{Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)}$$?

Accepted Answer

Zinc is oxidized; copper is reduced.

Question 15

Which step is necessary when balancing a redox reaction in basic solution?

Accepted Answer

Add $$\mathrm{OH^-} to $$neutralize $$\mathrm{H^+}.$$

Question 16

Which of the following best explains why gold is used for jewelry?

Accepted Answer

Gold is low on the activity series and resists oxidation.

Question 17

What is the purpose of a salt bridge in a voltaic cell?

Accepted Answer

To allow the flow of ions between the two half-cells.

Question 18

Which of the following is true about the oxidation state of an atom in a free element?

Accepted Answer

It is always zero.

Question 19

A fuel-cell breathalyzer measures blood alcohol level by:

Accepted Answer

Oxidizing ethyl alcohol at the anode and measuring the electrical current produced.

Chapter 16: Oxidation and Reduction – Study Notes for Introductory Chemistry

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