P1: 7 Oxidation, Reduction, and Redox Reactions

Question 1

What is oxidation?

Answer 1

The process of electron loss.

Question 2

What are oxidising agents?

Answer 2

Electron acceptors.

Question 3

What is reduction?

Answer 3

The process of electron gain.

Question 4

What are reducing agents?

Answer 4

Electron donors.

Question 5

What do oxidising agents do?

Answer 5

They oxidise the other reactant and are reduced themselves by gaining electrons.

Question 6

What do reducing agents do?

Answer 6

They reduce the other reactant and are oxidised themselves by the loss of electrons.

Question 7

What are the rules for assigning oxidation states?

Answer 7

On simple ions, the oxidation state is the charge on the ion.
In elements, the oxidation state is always 0.
The total of all oxidation states must always equal the overall charge on the species.
H is always nearly +1.
O is always nearly -2 (except in peroxides)

Question 8

How do you write half equations?

Answer 8

1. Balance the element changing oxidation state.
2. Sort out Os. For every O gained/lost, add/remove one H2O molecule.
3. Sort out Hs. For every H gained/lost, add/remove one H+ ion.
4. Calculate the oxidation states on each side of the equation.
5. Sort out electrons. If the oxidation state becomes more negative then it gains electrons.
6. Check if the total electric charge on the left equals the one on the left.

Question 9

How do you combine half equations?

Answer 9

Two half equations are added together so the electrons cancel out.
H+ ions and H2Os should cancel out as well.