3.1.7 Oxidation, reduction and redox reactions

Question 1

What is the oxidation state of an element?

Answer 1

The total number of electrons it has donated or accepted.

Question 2

What are the rules for assigning oxidation states?

Answer 2

1. All uncombined elements have an oxidation number of zero
2. The oxidation numbers of the elements in a compound add to zero
3. The oxidation number of a monoatomic ion is equal to the ionic charge
4. In a polyatomic ion, the sum of individual oxidation numbers of the elements adds up to the charge of the ion.

Question 3

What is oxidation?

Answer 3

The process of electron loss

Question 4

What is reduction?

Answer 4

The process of electron gain

Question 5

What is a redox reaction?

Answer 5

A reaction in which both oxidation and reduction occur together

Question 6

What is a reducing agent?

Answer 6

Loses electrons (they take place in the oxidation reaction and are an electron donor).
It causes the reduction of another reactant

Question 7

What is an oxidising agent?

Answer 7

Gains electrons (they take place in the reduction reaction and are an electron acceptor)
It causes the oxidation of another reactant

Question 8

What is a reduction half-equation?

Answer 8

Only shows the parts of a chemical reaction involved in reduction. Electrons are on the left

Question 9

What is an oxidation half-equation?

Answer 9

Only shows parts of a chemical reaction involved in oxidation.
Electrons are on the right

Question 10

When does hydrogen act as an oxidising agent?

Answer 10

When it reacts with elements in the s-block