3.1.7 Oxidation, reduction and redox equations

Question 1

Oxidation and reduction definitions

Answer 1

oxidation = loss of electrons, gain of oxygen, loss of hydrogen
Increases oxidation number
Reduction = gain of electrons, loss of oxygen, gain of hydrogen
Decreases oxidation number

Question 2

Oxidation number / state rules

Answer 2

Oxidation state of an element is 0
Oxidation state in a neutral compound is 0
Oxidation state in a charged compound adds up to total charge
Hydrogen has an oxidation state of +1
Oxygen has an oxidation state of 2-
If its a charged compound then the oxidation numbers of the elements must add to make the charge

Question 3

Oxidising and reducing agents

Answer 3

Oxidising agent = accepts electrons - meaning it is reduced and the other species is oxidised
Reducing agent = loses electrons - meaning it is oxidised meaning the other species is reduced

Question 4

Half equations

Answer 4

Used to show separate oxidation and reduction that occur in a redox reaction
Balanced according to the species present and the charges of the species

Question 5

Balancing half equations correctly method

Answer 5

Balance all species excluding oxygen and hydrogen
Balance oxygen by adding water
Balance the hydrogen by adding H+
Balance the charges using e-

Question 6

Combining equations to give the overall redox equation

Answer 6

Scale up to make electrons the same on both equations
Put everything on LHS of both eqs and put on LHS of new eq and same for RHS
And then cancel through

Question 7

disproportionation reaction

Answer 7

both oxidation and reduction happening at once