Oxidation states

Question 1

What is an oxidation state?

Answer 1

An oxidation state is similar to the valency of an element. For example we can either say iron(II) has a valency of 2 or that it is in oxidation state II or has an oxidation number +2.

Question 2

What are the rules for oxidation numbers?

Answer 2

1) The oxidation state of an unncombined element is 0.
2) Ions containing single atoms (e.g. Na^+) have an oxidation number the same as the charge on the ion (e.g. +1 for Na+).
3) The sum of all the oxidation numbers of all atoms in a neutral compound must add up to 0.
4) The sum of all the oxidation numbers of all atoms in a polyatomic ion must add up to the charge on the ion.

Question 3

What is the oxidation number of oxygen in most of its compounds?

Answer 3

-2

Question 4

What is the oxidation number of hydrogen in most of its compounds?

Answer 4

+1

Question 5

What is the oxidation number of fluorine in all its compounds?

Answer 5

-1

Question 6

Give the definition of oxidation.

Answer 6

An increase in oxidation number.

Question 7

Give the deifintion of reduction.

Answer 7

A decrease in oxidation number.

Question 8

What kind of compounds are usually good oxidising or reducing agents?

Answer 8

Compounds containing metals in high oxidation states tend to be good oxidising agents.
Compounds containing metals in low oxidation states tend to be good reducing agents.