redox reactions (chapter 7)

Question 1

What is a simple definition of oxidation?

Answer 1

Gain of oxygen by an element

Example: Magnesium reacts with oxygen to form magnesium oxide.

Question 2

What is a simple definition of reduction?

Answer 2

Loss of oxygen

Example: Copper(II) oxide reacts with hydrogen to form copper and water.

Question 3

What acronym helps to remember the definitions of oxidation and reduction?

Answer 3

OIL RIG

OIL stands for Oxidation Is Loss, RIG stands for Reduction Is Gain.

Question 4

What type of reactions are oxidation and reduction always part of?

Answer 4

Redox reactions

Examples include photosynthesis and respiration.

Question 5

How can oxidation be defined in terms of hydrogen?

Answer 5

Removal of hydrogen from a compound.

Question 6

How can reduction be defined in terms of hydrogen?

Answer 6

Addition of hydrogen to a compound.

Question 7

What are the two methods to determine if a substance has been oxidised or reduced?

Answer 7

• Electron transfer
• Changes in oxidation number.

Question 8

What is a half-equation?

Answer 8

An equation showing either oxidation or reduction separately.

Question 9

What happens to sodium in the reaction with chlorine?

Answer 9

Sodium is oxidised.

Half-equation: Na → Na+ + e−.

Question 10

What happens to chlorine in the reaction with sodium?

Answer 10

Chlorine is reduced.

Half-equation: Cl2 + 2e− → 2Cl−.

Question 11

What is the oxidation number of an uncombined element?

Answer 11

Zero.

Question 12

What is the oxidation number of Group 1 elements?

Answer 12

+1.

Question 13

What is the oxidation number of Group 2 elements?

Answer 13

+2.

Question 14

What is the oxidation number of fluorine?

Answer 14

-1.

Question 15

What is the oxidation number of hydrogen in most compounds?

Answer 15

+1.

Question 16

What is the oxidation number of oxygen in most compounds?

Answer 16

-2.

Question 17

What does a higher positive oxidation number indicate?

Answer 17

More oxidised.

Question 18

What does a higher negative oxidation number indicate?

Answer 18

More reduced.

Question 19

What is the sum of the oxidation numbers in a compound?

Answer 19

Zero.

Question 20

What does the oxidation number of an element in a monatomic ion equal?

Answer 20

The charge of the ion.

Question 21

How can you determine the oxidation number of sulfur in sodium sulfide (Na2S)?

Answer 21

S = -2.

Question 22

What is the oxidation number of nitrogen in the nitrate ion (NO3−)?

Answer 22

+5.

Question 23

What is the relationship between oxidation number changes and redox reactions?

Answer 23

• Oxidation is an increase in oxidation number.
• Reduction is a decrease in oxidation number.

Question 24

What is an oxidising agent?

Answer 24

A substance that brings about oxidation by removing electrons.

Question 25

What is a reducing agent?

Answer 25

A substance that brings about reduction by donating electrons.

Question 26

What is the oxidation number of each hydrogen atom in the reaction?

Answer 26

+1

Question 27

What role does nitric acid play in the reaction?

Answer 27

Oxidising agent

Question 28

What role does tin play in the reaction?

Answer 28

Reducing agent

Question 29

Define an oxidising agent.

Answer 29

A substance which brings about oxidation by removing electrons from another atom or ion

Question 30

What happens to the oxidation number of the oxidising agent during a redox reaction?

Answer 30

It decreases

Question 31

List typical oxidising agents

Answer 31

* Oxygen * Chlorine * Potassium manganate(VII)

Question 32

Define a reducing agent.

Answer 32

A substance that brings about reduction by donating electrons to another atom or ion

Question 33

What happens to the oxidation number of the reducing agent during a redox reaction?

Answer 33

It increases

Question 34

List typical reducing agents.

Answer 34

* Hydrogen * Potassium iodide * Reactive metals such as aluminium

Question 35

In every redox reaction, what must be present?

Answer 35

An oxidising agent and a reducing agent

Question 36

What is the oxidation number change for Mn in the reaction MnO4− + 5Fe2+ + 8H+ → Mn2+ + 5Fe3+ + 4H2O?

Answer 36

Decreases from +7 to +2

Question 37

What is the oxidation number change for Fe in the same reaction?

Answer 37

Increases from +2 to +3

Question 38

How does the ability of a substance to act as an oxidising or reducing agent depend?

Answer 38

On its standard electrode potential

Question 39

Can hydrogen peroxide act as both an oxidising and reducing agent?

Answer 39

Yes

Question 40

What is the systematic name for FeCl2?

Answer 40

Iron(II) chloride

Question 41

What is the oxidation number of iron in iron(II) chloride?

Answer 41

+2

Question 42

What is the systematic name for FeCl3?

Answer 42

Iron(III) chloride

Question 43

What is the oxidation number of nitrogen in N2O?

Answer 43

+1

Question 44

What is the oxidation number of nitrogen in NO?

Answer 44

+2

Question 45

What is the oxidation number of nitrogen in NO2?

Answer 45

+4

Question 46

What is the oxidation number of nitrogen in the NO2− ion?

Answer 46

+3

Question 47

What is the oxidation number of nitrogen in the NO3− ion?

Answer 47

+5

Question 48

What is the naming convention for ions containing oxygen and another element?

Answer 48

They end in '-ate'

Question 49

What is the name of H3PO3 based on its oxidation number of phosphorus?

Answer 49

Phosphoric(III) acid

Question 50

What is the name of HClO4 based on its oxidation number of chlorine?

Answer 50

Chloric(VII) acid

Question 51

What is the formula for sodium nitrate(III)?

Answer 51

NaNO2

Question 52

What is the formula for sodium nitrate(V)?

Answer 52

NaNO3

Question 53

What is the balanced equation for the reaction of copper(II) oxide with ammonia?

Answer 53

3CuO + 2NH3 → 3Cu + N2 + 3H2O

Question 54

What is the unbalanced equation for the reaction of manganate(VII) ions with Fe2+ ions?

Answer 54

MnO4− + Fe2+ + H+ → Mn2+ + Fe3+ + H2O

Question 55

What is the oxidation number change for chlorine during the disproportionation reaction in cold aqueous sodium hydroxide?

Answer 55

0 to -1 and 0 to +1

Question 56

What is the product of the disproportionation reaction of chlorine with dilute alkali?

Answer 56

NaCl and water

Question 57

What is the product of the disproportionation reaction of chlorine with hot concentrated alkali?

Answer 57

Chloride ions, chlorate(V) ions, and water