Chapter 9: Redox Reactions

Question 1

What is oxidation?

Answer 1

Loss of electrons.

Question 2

What is reduction?

Answer 2

Gain of electrons.

Question 3

Why are oxidation and reduction always paired?

Answer 3

They occur together in a redox reaction.

Question 4

What is the mnemonic for oxidation and reduction?

Answer 4

OILRIG (Oxidation Is Loss

Question 5

What is a redox reaction?

Answer 5

A chemical reaction with changes in oxidation states.

Question 6

What happens to oxidation state during oxidation?

Answer 6

It increases.

Question 7

What happens to oxidation state during reduction?

Answer 7

It decreases.

Question 8

What does a positive oxidation number indicate?

Answer 8

The element is oxidized.

Question 9

What does a negative oxidation number indicate?

Answer 9

The element is reduced.

Question 10

What is sulfur’s most reduced form?

Answer 10

H₂S.

Question 11

What are sulfur’s most oxidized forms?

Answer 11

SO₃ and H₂SO₄.

Question 12

What are oxidation states used for in systematic names?

Answer 12

To indicate oxidation numbers in compounds.

Question 13

How is the oxidation number of carbon determined in organic compounds?

Answer 13

By the type of bonds it forms.

Question 14

What is the oxidizing agent in a redox reaction?

Answer 14

The reactant that accepts electrons.

Question 15

What is the reducing agent in a redox reaction?

Answer 15

The reactant that donates electrons.

Question 16

Is water a strong oxidizing or reducing agent?

Answer 16

Neither; it is weak in both roles.

Question 17

What does the activity series predict?

Answer 17

Whether a metal displacement reaction is feasible.

Question 18

Which metals are the strongest reducing agents?

Answer 18

Reactive metals like K

Question 19

Which non-metals are the strongest oxidizing agents?

Answer 19

Reactive non-metals.

Question 20

What is KMnO₄ in acidic solution used for?

Answer 20

As an oxidizing agent.

Question 21

What type of agent is iodine in redox reactions?

Answer 21

It can act as both an oxidizing and reducing agent.

Question 22

What is the general rule for oxidation numbers in neutral compounds?

Answer 22

The sum equals zero.

Question 23

What is the oxidation number of hydrogen in most compounds?

Answer 23

1

Question 24

What is the oxidation number of oxygen in most compounds?

Answer 24

-2

Question 25

What is the oxidation number of elements in their pure form?

Answer 25

0

Question 26

What is the oxidation number of alkali metals in compounds?

Answer 26

1

Question 27

What is the oxidation number of alkaline earth metals in compounds?

Answer 27

2

Question 28

How do you balance redox equations?

Answer 28

By equalizing electrons lost and gained.

Question 29

What is the oxidation number of fluorine in compounds?

Answer 29

-1

Question 30

How is the oxidation number of chlorine determined in ClO⁻?

Answer 30

1

Question 31

How is the oxidation number of sulfur in SO₄²⁻ determined?

Answer 31

6

Question 32

How is the oxidation number of nitrogen in NO₃⁻ determined?

Answer 32

5

Question 33

What is the significance of the oxidation state of +3 for iron?

Answer 33

It indicates the Fe³⁺ ion.

Question 34

Why are reactive metals good reducing agents?

Answer 34

They readily lose electrons.

Question 35

Why are reactive non-metals good oxidizing agents?

Answer 35

They readily gain electrons.

Question 36

What is the oxidation number of sulfur in H₂SO₃?

Answer 36

4

Question 37

What is the role of KMnO₄ in redox titrations?

Answer 37

It acts as a strong oxidizing agent.

Question 38

Why is balancing charges important in redox equations?

Answer 38

To ensure the reaction obeys the law of conservation of charge.

Question 39

What is the oxidation number of chromium in Cr₂O₇²⁻?

Answer 39

6

Question 40

What is the oxidation number of manganese in MnO₄⁻?

Answer 40

7

Question 41

How does an oxidizing agent affect another substance?

Answer 41

It causes the other substance to lose electrons.

Question 42

How does a reducing agent affect another substance?

Answer 42

It causes the other substance to gain electrons.

Question 43

What happens to the oxidizing agent during a redox reaction?

Answer 43

It is reduced.

Question 44

What happens to the reducing agent during a redox reaction?

Answer 44

It is oxidized.

Question 45

How do you determine the total oxidation number in a polyatomic ion?

Answer 45

It equals the ion's charge.

Question 46

What is the oxidation number of phosphorus in H₃PO₄?

Answer 46

5

Question 47

What is the oxidation number of sulfur in H₂S₂O₃?

Answer 47

+2 and +6 (average +4).

Question 48

What is the oxidation number of nitrogen in NH₃?

Answer 48

-3

Question 49

What is the oxidation number of carbon in CO₂?

Answer 49

4

Question 50

How do you identify a redox reaction?

Answer 50

Look for changes in oxidation states.

Question 51

What is the activity series order of alkali metals?

Answer 51

K > Na > Li > others.

Question 52

What are spectator ions in redox reactions?

Answer 52

Ions that do not participate in the redox process.

Question 53

What is the role of electrons in redox reactions?

Answer 53

They are transferred between species.

Question 54

What does an increase in oxidation number signify?

Answer 54

Oxidation.

Question 55

What does a decrease in oxidation number signify?

Answer 55

Reduction.

Question 56

What is the oxidation number of hydrogen in hydrides (e.g.

Answer 56

NaH)?

Question 57

What happens in a displacement reaction?

Answer 57

A more reactive metal displaces a less reactive metal from its compound.

Question 58

Why is balancing hydrogen and oxygen important in redox reactions?

Answer 58

To maintain mass balance.

Question 59

What is the oxidation number of oxygen in peroxides (e.g.

Answer 59

H₂O₂)?

Question 60

How does KMnO₄ change color when reduced?

Answer 60

Purple to colorless.