Chapter 20 Key Concepts

Question 0

Define oxidation and reduction in terms of the gain or loss of electrons.

Answer 0

Losing electrons is oxidation. Gaining electrons is reduction.

Question 1

Define oxidation and reduction in terms of the gain or loss of oxygen.

Answer 1

The substance gaining oxygen is oxidized, while the substance losing oxygen is reduced

Question 2

What happens to the atoms in an iron nail that corrodes?

Answer 2

Iron corrodes by being oxidized to ions of iron by oxygen

Question 6

In any redox reaction, how does the increase in oxidation number of the species oxidized compare to the decrease in oxidation number of species reduced?

Answer 6

In a balanced redox equation, the total increase must be balanced by the total decrease

Question 7

What is the general rule for assigning oxidation numbers?

Answer 7

A bonded atom’s oxidation number is the charge that it would have if the electrons in the bond were assigned to the atom of the more electronegative element

Question 8

How is a change in oxidation number related to the process of oxidation and reduction?

Answer 8

An increase in the oxidation number of an atom or ion indicates oxidation. A decrease indicates reduction.

Question 9

What happens to the oxidation number of a species reacting in a redox reaction?

Answer 9

If the oxidation number of an element in a reacting species changes, then that element has undergone either oxidation or reduction. Therefore, the reaction as a whole must be a redox reaction.