Question

Q.4- Identify reducing agent :-
3MnO2 + 4AL
3Mn + 2A1203
Which is more reactive, Mn or Al and why?​

Answer 1

First let us consider the unbalanced chemical reaction:

MnO₂ + Al → Mn + Al₂O₃

Now calculate the oxidation number of each element.

Oxidation number of Mn in MnO₂:

We know that oxidation number of Oxygen is -2.

So,

x + 2(-2) = 0

⇒ x - 4 = 0

⇒ x = 4

Oxidation number of Al in Al₂O₃:

Oxidation number of Oxygen is -2.

So,

2x + 3(-2) = 0

⇒ 2x - 6 = 0

⇒ 2x = 6

⇒ x = 3

Oxidation number of Mn and Al is 0 since they are single elements.

On observing the oxidation number of Al in Al₂O₃ has increased from 0 to 3 (in the reactant).

Increase in oxidation number is known as Oxidation.

∴ Al (Aluminium) is the Reducing Agent.

Since Aluminium acts as a strong reducing agent, aluminium is more reactive than Manganese.