Question

Statement I: $A{{l}^{3+}}+3{{e}^{-}}\to Al$ is a correctly balanced oxidation reaction because ,

Statement II: $A{{l}^{3+}}+3{{e}^{-}}\to Al$ correctly demonstrates conservation of mass and conservation of charge.
[A] True, True
[B] True, False
[C] False, True
[D] False, False

Answer 1

Hint: Oxidation is the loss of electrons and thus forms a positive species or if the starting reactant is neutral, it forms a neutral species. Reduction is the opposite of oxidation as it is the gain of electrons. The conservation of charge and mass holds true if the equation mentioned to us is balanced correctly i.e. both charge and mass on both sides are the same.

Complete step by step answer:
Here, we have two statements and we have to identify if they are correct or not. Let us take them one by one and discuss if they are correct or not.
In the first statement we have that $A{{l}^{3+}}+3{{e}^{-}}\to Al$ is a correctly balanced oxidation reaction.
We know that oxidation is referred to as loss of electron during a reaction. In the given reaction, aluminium cation accepts 3 electrons and gets converted to aluminium which is a reduction reaction as reduction means gain of electrons. Therefore, the first statement is incorrect.

Now let us discuss the second statement.
The second statement says that $A{{l}^{3+}}+3{{e}^{-}}\to Al$ correctly demonstrates conservation of mass and conservation of charge. We know that the law of conservation of mass states that for a closed system, where transfer of mass and energy takes place, the mass of the system is always constant at any time as the mass of the system cannot change. Thus, mass can neither be added nor removed but only transfers from one form to another.
Similarly, conservation of charge also states that charge of the universe, the system is always constant and transforms from one form to another.
Here, on the left hand side, we have a positive charge of +3 on aluminium and 3 electrons which neutralises each other and thus gives us aluminium so the mass of the system is conserved and so is the charge. Thus the equation correctly demonstrates the conservation of charge and mass and is a balanced equation. Therefore, the second statement is correct.
As we can see from the above discussion that the first statement is incorrect and the second statement is correct. So, the correct answer is “Option C”.

Note: A compound which undergoes oxidation itself to reduce some other compound is known as a reducing agent and a compound which undergoes reduction itself to oxidise some other compound is known as an oxidising agent. We know that a substance which undergoes oxidation loses electrons and a substance which undergoes reduction gains electrons. An oxidising agent will gain electrons because it undergoes reduction itself and a reducing agent will lose electrons because it undergoes oxidation itself.