2. Oxidation, Reduction, and Redox Reactions

Question 1

Oxidation Definition:

Answer 1

• loss of e-
• (oxidation state increases)

Question 2

Reduction Definition:

Answer 2

• Gain of e-
• (oxidation state decreases)

Question 3

Reducing Agent Definition:

Answer 3

• e- donor (loses e-)
• a reducing agent is itself oxidised

Question 4

Oxidising Agent Definition:

Answer 4

• e- acceptor (gains e-)
• an oxidising agent is itself reduced

Question 5

What occurs in a redox reaction?

Answer 5

oxidation and reduction takes place together

Question 6

Rules for finding oxidation states:

Answer 6

1. uncombined elements/diatomic molecules have an oxidation state of 0
2. sum of all the oxidation states in a compound is 0
3. oxidation state of a simple ions is equal to its charge
4. sum of all the oxidation states in a complex ion is equal to its charge

Question 7

If a substance is oxidised, the oxidation state (increases/decreases) …

Answer 7

increases

Question 8

If a substance is reduced, the oxidation state (increases/decreases) …

Answer 8

decreases

Question 9

Rules for balancing half equations:

Answer 9

1. Balance the main atom (not H or O)
2. Balance O using H2O
3. Balance H using H+
4. Balance charges using e- (add more to positive side)

Question 10

Rules for combining half equations:

Answer 10

1. multiply 1 or both half equations until they both contain the same number of e-
2. add the reactants from both half equations together
3. add the products from both half equations together
4. cancel out the e-

Question 11

What occurs in a disproportionation reaction?

Answer 11

1 atom is both reduced and oxidised