Redox Reactions

Question 1

What is oxidation?

Answer 1

The loss of electrons and gain of oxygen. This causes an increase in the oxidation number.

Question 2

What is reduction?

Answer 2

The gain of electrons and loss of oxygen. This causes a decrease in the oxidation number.

Question 3

What is the oxidation number used for?

Answer 3

• To tell if reduction or oxidation has taken place.
• To work out what has been oxidised/ reduced.
• To construct half equations.
• To balance redox equations.

Question 4

What are the periodic table group’s oxidation number rules?

Answer 4

Group 1= +1
Group 2= +2
Group 3= +3

Question 5

What is Hydrogen’s oxidation number rule?

Answer 5

+1 except atom (H) and molecule (H2) = 0
-1 in hydride ion, H- in sodium hydride (NaH)

Question 6

What is Oxygen’s oxidation number rule?

Answer 6

-2 except atom (O) and molecule (O2)= 0
-1 in hydrogen peroxide (H2O2)
+2 in F2O

Question 7

What is Fluorine’s oxidation number rule?

Answer 7

-1 except atom (F) and molecule (F2)= 0

Question 8

What is Chlorine’s oxidation number rule?

Answer 8

-1 except atom (Cl) and molecule (Cl2), in molecules or ions with F or O= 0

Question 9

What does the sum of the oxidation numbers add up to?

Answer 9

0

Question 10

What is the formula for Sulfate?

Answer 10

SO4²+