1.7 Oxidation, Reduction & Redox Equations

Question 1

What is oxidation in terms of electrons?

Answer 1

Process where there is an electron loss

Question 2

What is reduction is terms of electrons?

Answer 2

Process where there is an electron gain

Question 3

What is oxidation in terms of hydrogen

Answer 3

Process where there is a hydrogen loss

Question 4

What is reduction in terms of hydrogen

Answer 4

Process where there is a hydrogen gain

Question 5

What is oxidation in terms of oxygen?

Answer 5

Process where there is an oxygen gain

Question 6

What is reduction in terms of oxygen?

Answer 6

Process where there is an oxygen loss

Question 7

What is an oxidising agent?

Answer 7

Compound that is an electron/hydrogen acceptor or oxygen donor

Question 8

What is a reducing agent?

Answer 8

Compound that is an electron/hydrogen donor or oxygen acceptor

Question 9

What happens when a reducing agent loses electrons?

Answer 9

It becomes oxidised
i.e. Ca –> Ca2+ + 2e-

Question 10

What happens when an oxidising agent gains electrons?

Answer 10

It becomes reduced
i.e. 1/2 O2 + 2e- –> O2-

Question 11

How does oxidation change an oxidation number?

Answer 11

increases

Question 12

How does oxidation change an oxidation number?

Answer 12

Increases

Question 13

How does reduction change an oxidation number?

Answer 13

Decreases

Question 14

What is the oxidation number of an uncombined element? And give an example.

Answer 14

0. Cl2, F2 etc.

Question 15

What is the oxidation number of an ion? And give an example.

Answer 15

It’s the overall charge of the ion. Cl- is -1.

Question 16

What is the oxidation number of Group 1 Metals? And give an example.

Answer 16

ALWAYS +1. KCl.

Question 17

What is the oxidation number of Group 2 Metals? And give an example.

Answer 17

ALWAYS +2. MgO.

Question 18

What is the oxidation state of Aluminium? And give an example.

Answer 18

ALWAYS +3. Al2O3.

Question 19

What is the oxidation number of Hydrogen? And give an example.

Answer 19

Usually +1. Except in hydrides (combined with metal), then it’s -1. KF or NaH

Question 20

What is the oxidation number of Chlorine? And give an example.

Answer 20

Usually -1. Except with F/O. KCl or in ClF3 it’s +3.

Question 21

What is the oxidation number of Fluorine? And give an example.

Answer 21

ALWAYS -1. Highest oxidation strength.

Question 22

What is the oxidation number of Oxygen? And give an example.

Answer 22

Usually -2. Except in peroxides & +2 in OF2. Li2O or in H2O2 it’s -1.

Question 23

What are half-equations?

Answer 23

Show reduction and oxidation stages in two separate equations.

Question 24

What must half-equations always include?

Answer 24

Electrons.

Question 25

What is the process of forming half equations?

Answer 25

1. Write species before and after
2. Balance any atoms (NOT O/H)
3. Balance Oxygen atoms with H2O
4. Balance Hydrogen atoms with H+
5. Balance charges with electrons (e-)

Question 26

How do you identify an oxidation half-equation?

Answer 26

Electrons on RHS.

Question 27

How do you identify a reduction half-equation?

Answer 27

Electrons on LHS

Question 28

What is the sycronym to remember oxidation and reduction?

Answer 28

Oxidation Reduction
Is Is
Loss Gain

Question 29

How do you create a full-equation from two half-equations?

Answer 29

Balance electrons on both sides and combine equations cancelling out electrons.

TIP: fully simplify every compound