3: Redox I

Question 1

What are the definitions of oxidation

Answer 1

• Addition of oxygen
• Loss of hydrogen
• Loss of electrons

Question 2

What are the definitions of reduction

Answer 2

• Loss of oxygen
• Addition of hydrogen
• Gain of electrons

Question 3

What is OILRIG

Answer 3

Oxidation is loss of electrons, reduction is gain of electrons

Question 4

What is oxidation number

Answer 4

The charge that would exist on an individual atom if the bonding were completely ionic

Question 5

What is the oxidation number of uncombined elements

Answer 5

0

Question 6

What is the oxidation number of a cation

Answer 6

+ (charge)

Question 7

What is the oxidation number of an anion

Answer 7

• (charge)

Question 8

What do roman numerals indicate

Answer 8

The oxidation state of ions in a compound

Question 9

What is the oxidation state of a mono-atomic atom (e.g. Zn+2)

Answer 9

The same as the charge on the ion (e.g. +2)

Question 10

What is the sum of the oxidation numbers in a compound (e.g. NaCl)

Answer 10

0

Question 11

What is the sum of oxidation in an ion (e.g. SO4-2)

Answer 11

Equal to the charge (e.g. -2)

Question 12

What is given the oxidation number in compounds or ions

Answer 12

The more electronegative element is given the negative value

Question 13

What is the oxidation state of group 1 elements

Answer 13

Always +1

Question 14

What is the oxidation state of group 2 elements

Answer 14

Always +2

Question 15

What is the oxidation state of fluorine

Answer 15

Always -1

Question 16

What is the oxidation state of hydrogen

Answer 16

+1 (except in metal hydrides where it’s -1)

Question 17

What is the oxidation state of oxygen

Answer 17

-2 (except in peroxides where it’s -1, and F2O where it’s +2)

Question 18

What is the oxidation number in molecules or compounds

Answer 18

The sum of the oxidation numbers is 0

Question 19

How do you determine the element with a positive oxidation state in a molecule/compound

Answer 19

The more electronegative value has the negative value

Question 20

How to determine the oxidation number

Answer 20

• Group in periodic table
• Other elements in formula
• Following oxidation rules
• Certain species can have varying oxidation states!

Question 21

How can oxidation and reduction in terms of electron transfer be demonstrated

Answer 21

Question 22

What is an oxidising agent

Answer 22

A substance that oxidises another atom/ion by causing it to lose electrons, whilst itself gaining electrons and being reduced. Its oxidation number becomes more negative

Question 23

What is a reducing agent

Answer 23

A substance that reduces another atom/ion by causing it to gain electrons, whilst itself losing electors and being oxidised. It’s oxidation number becomes more positive

Question 24

What is a redox reaction

Answer 24

Oxidation and reduction must occur, there is both a reducing and oxidising agent present

Question 25

How to determine the strongest oxidising/reducing agent

Answer 25

The species which oxidation number changes the most dramatically

Question 26

What is a disproportionation reaction

Answer 26

A reaction in which the same species is simultaneously oxidised and reduced

Question 27

How to balance disproportion reactions

Answer 27

• Deduce oxidation number changes
• Balance oxidation number changes
• Balance charges

Question 28

What are the usual oxidation states of metals

Answer 28

• Positive values in compounds
• Value usually that of the group number
• With several oxidation number possibilities the value is no higher than the group number
• Generally oxidised

Question 29

What are the usual oxidation numbers of non-metals

Answer 29

• Mostly negative based on usual ions
• Can have values up to their group number
• Generally reduced

Question 30

How to write and balance full ionic equations

Answer 30