Redox

Question 1

Oxidation number

Answer 1

• Based on a set of rules that apply to atoms, and can be thought of as the number of electrons involved in bonding to a different element.

Question 2

OIL RIG

Answer 2

Oxidation Is Loss of electrons; Reduction Is Gain of electrons

• Reducing agents: gives electrons to another substance and becomes oxidised.
• Oxidising agent: removes electrons from another substance and becomes reduced.

Question 3

Oxidation rules for elements

Answer 3

• Oxidation no. is always 0 for elements.
• In pure element, any bonding is to atoms of same element.
• So in H2, O2, Na and Fe oxidation no. of each atom of the element is 0.

Question 4

Oxidation rules for compounds and ions

Answer 4

• Each atom in a compound has an oxidation no.
• An oxidation no. has a sign which is placed BEFORE the no.
• Oxidation no. is numerically the same as ionic charge.

Question 5

Special cases for ox. no.

Answer 5

H in metal hydrides= -1
O in peroxides= -1
O bonded to F= +2

Question 6

Rule for combined atoms:

Answer 6

Sum of the oxidation no. = total charge

Question 7

Redox in terms of oxidation no.

Answer 7

• Reduction is DECREASE in ox. no.

- Oxidation is INCREASE in ox. no.