Question 1

Which of the following best describes the chemical process occurring when a copper wire is placed in a solution of silver nitrate, as shown in the images above?

Accepted Answer

Copper metal is oxidized to copper(II) ions, and silver ions are reduced to silver metal.

Question 2

What is the net ionic equation for the reaction between copper metal and aqueous silver ions?

Accepted Answer

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

Question 3

Which species acts as the oxidizing agent in the reaction between copper metal and silver nitrate solution?

Accepted Answer

Silver ion, Ag$$^+(aq)$$

Question 4

What is the oxidation number of copper in Cu(NO$$_3$$)$$_2$$?

Accepted Answer

$$+2$$

Question 5

Which of the following half-reactions correctly represents the reduction process in the reaction between copper and silver nitrate?

Accepted Answer

$$\mathrm{Ag}^+(aq) + e^- \rightarrow \mathrm{Ag}(s)$$

Question 6

In the reaction $$\mathrm{Cu}(s) + 2\,\mathrm{Ag}^+(aq) \rightarrow 2\,\mathrm{Ag}(s) + \mathrm{Cu}^{2+}(aq)$$, how many electrons are transferred per copper atom?

Accepted Answer

2 electrons

Question 7

Which statement best explains why the solution turns blue during the reaction between copper wire and silver nitrate?

Accepted Answer

Copper(II) ions are released into the solution, which are blue in color.

Question 8

Which of the following is a correct description of oxidation in a redox reaction?

Accepted Answer

A process in which an atom loses electrons.

Question 9

Given the reaction $$\mathrm{Al}(s) + 3\,\mathrm{Ag}^+(aq) \rightarrow \mathrm{Al}^{3+}(aq) + 3\,\mathrm{Ag}(s)$$, what is the oxidation half-reaction?

Accepted Answer

$$\mathrm{Al}(s) \rightarrow \mathrm{Al}^{3+}(aq) + 3e^-$$

Question 10

Which of the following best describes a spectator ion in a redox reaction?

Accepted Answer

An ion that does not participate in the electron transfer and remains unchanged.

Question 11

In the reaction $$\mathrm{NiO}(s) + \mathrm{C}(s) \rightarrow \mathrm{Ni}(s) + \mathrm{CO}(g)$$, which element is oxidized?

Accepted Answer

Carbon

Question 12

What is the oxidation number of nitrogen in the nitrate ion, NO$$_3^-$$?

Accepted Answer

$$+5$$

Question 13

Which of the following rules is used to assign oxidation numbers in compounds?

Accepted Answer

The oxidation number of oxygen is usually $$-2$$, except in peroxides.

Question 14

Which of the following statements about oxidizing and reducing agents is correct?

Accepted Answer

The oxidizing agent is reduced and gains electrons.

Question 15

In the reaction $$2\,\mathrm{H}_2(g) + \mathrm{O}_2(g) \rightarrow 2\,\mathrm{H}_2\mathrm{O}(g)$$, what happens to the oxidation number of hydrogen?

Accepted Answer

It increases from $$0 to$$ $$+1.$$

Question 16

Which of the following is the correct oxidation number for sulfur in SO$$_4$$^{2-}$$?

Accepted Answer

$$+6$$

Question 17

A student observes that a blue solution forms when a metal wire is placed in a colorless solution. Which of the following best explains this observation?

Accepted Answer

The metal wire is oxidized, releasing metal ions that impart a blue color to the solution.

Question 18

Which of the following best describes the change in oxidation number for an entity that is reduced?

Accepted Answer

Its oxidation number decreases.

Question 19

Why must oxidation and reduction always occur together in a redox reaction?

Accepted Answer

Because electrons cannot be created or destroyed, so one species must lose electrons while another gains them.

Lesson 9.1: Electron Transfer Reactions and Oxidation–Reduction (Redox) Chemistry

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