2.1.5 - Redox

Question 1

Oxidation rules

Answer 1

Peroxides (where there it is 2 oxygens bonded to another element eg. BaO_{2 or MgO2}

Question 2

What is oxidation in terms of oxygen, electrons and hydrogen

Answer 2

Oxygen : Addition of oxygen
Electrons : Loss of electrons
Hydrogen : Removal of hydrogen

Question 3

What is reduction in terms of Oxygen, Electrons and Hydrogen

Answer 3

Oxygen : Removal of oxygen
Electrons : Gain of electrons
Hydrogen : Addition of hydrogen

Question 4

Explanation of : (c) use of a Roman numeral to indicate the magnitude of the oxidation number when an element may have compounds/ions with different oxidation numbers.

Answer 4

Eg. Suggest a formula for the Chlorate (V) ion
- From its name this ion must contain only Chlorine and
Oxygen
- It must be overall negative
- The Oxidation number of the Chlorine is +5
- So add -2 Oxygen atoms until the ion just becomes
negative
- So, with a +5 Cl
- Adding one -2 Oxygen atom would give us ClO3+
which isn’t negative
- Adding another gives us ClO2+ still isn’t negative
But adding another gives us ClO3-

Question 5

What is a disproportionation reaction ?

Answer 5

when an element is both oxidised and reduced in the same reaction.

Question 6

Half equations

Answer 6