Redox

Question 1

What can the process of oxidation and reduction be expressed in terms of

Answer 1

Electron transfer

Question 2

Oxidation

Answer 2

Loss of electrons

Question 3

Reduction

Answer 3

Gain of electrons

Question 4

Where do oxidation and reduction occur

Answer 4

Together in a redox reaction

Question 5

Half equations

Answer 5

Seperate equations showing oxidation and reduction processes

Question 6

What must a half equation be balanced in terms of

Answer 6

Atoms and charge

Question 7

Oxidation state

Answer 7

Number of electrons involved when an atom forms a bond

Question 8

What does oxidation state refer to

Answer 8

One atom of the element in a compound or ion

Question 9

What does the oxidation state have

Answer 9

A number and a sign

Question 10

What does an uncombined element have

Answer 10

An oxidation state of zero

Question 11

What is the oxidation state of group one elements in compounds

Answer 11

+1

Question 12

What is the oxidation state of group 2 elements in compounds

Answer 12

+2

Question 13

What is the oxidation state of group 3 elements in compounds

Answer 13

+3

Question 14

What is the oxidation state of hydrogen in compounds

Answer 14

+1

Question 15

What is the oxidation state of fluorine in compounds

Answer 15

-1

Question 16

What is the oxidation state of oxygen in compounds

Answer 16

-2

Question 17

What is the oxidation state of chlorine in compounds

Answer 17

-1

Question 18

What is the exception to the oxidation state rule of hydrogen in compounds

Answer 18

Hydride ions have an oxidation state of 1-

Question 19

What are the exceptions to the rule of oxidation state in oxygen in compounds

Answer 19

With fluorine/peroxide ions

Question 20

What are the exceptions to the oxidation state rule in chlorine in compounds

Answer 20

With oxygen

Question 21

What is the rule for oxidation state in compounds

Answer 21

The oxidation state of each atom in the compounds formula counts separately and the numerical sum is zero

Question 22

What is the oxidation state rule for an element existing as an ion

Answer 22

The oxidation state is the charge on the ion

Question 23

What is the oxidation state rule for compound ions

Answer 23

The sum of the oxidation states of the atoms is the charge on the ion

Question 24

What are Roman numerals in chemical names used to indicate

Answer 24

The oxidation state of the appropriate element

E.g. Iron (II) oxide- metals oxidation state +2

Question 25

What can we work out by assigning oxidation states

Answer 25

Which species have been oxidised and which reduced without writing half equations

Question 26

Oxidation (OS)

Answer 26

Increase in oxidation state

Question 27

Reduction (OS)

Answer 27

Decrease in oxidation state

Question 28

What must occur in a redox reaction in order to cause the loss of electrons from one species

Answer 28

Another species must accept the electrons

Question 29

What is the species that accepts electrons and causes oxidation called

Answer 29

An oxidising agent

Question 30

In order for a species to gain electrons in a redox reaction what must occur

Answer 30

Another species must donate electrons

Question 31

What is the species that donates electrons and causes reduction called

Answer 31

Reducing agent

Question 32

Oxidising agent

Answer 32

Species that accepts electrons

Question 33

Reducing agent

Answer 33

Is a species that donates electrons

Question 34

What must you make sure balance when writing half equations

Answer 34

Atoms and charges

Question 35

What is the first step in constructing complex half equations

Answer 35

Write down the formulae for the reactants and products and balance the atoms undergoing redox

Question 36

How to balance oxygen atoms in half equations

Answer 36

Add water to side with least oxygen

Question 37

How to balance hydrogen atoms in half equations

Answer 37

Add h+ ions to side with least hydrogen

Question 38

How to balance the charges in half equations

Answer 38

Add electrons to most positive side

Question 39

What must each equations show when combining half equations

Answer 39

One side must show reduction and the other must show oxidation

Question 40

What must the number of electrons being transferred be when combining half equations

Answer 40

The same- you may have to multiply one or both of the half equations

Question 41

Which species must be cancelled when combining half equations

Answer 41

Any species that appears on both sides