Question

In the following reaction, the change in oxidation state of Magnesium is: 3Mg(s) + N₂(g) → Mg₃N₂(s)

• A. 0 to +2
• B. 0 to +3
• C. 0 to +4
• D. 0 to +6
• E. 0 to -2

Hint:

Group 2 elements (like Mg) almost always show a +2 oxidation state in their compounds.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Oxidation state (or oxidation number) is a number assigned to an element in a chemical combination which represents the number of electrons lost or gained by an atom of that element. We need to apply the rules for assigning oxidation states to magnesium on both the reactant and product sides of the equation.
Step 2: Detailed Explanation:

Reactant side: The reactant is Magnesium in its solid elemental form, Mg\(_{(s)}\). According to the rules of oxidation states, any element in its free or uncombined state has an oxidation state of 0.

Product side: The product is magnesium nitride, Mg\(_3\)N\(_2\). This is an ionic compound.
Magnesium (Mg) is an alkaline earth metal (Group 2). In its compounds, it almost always exhibits an oxidation state of +2.
Nitrogen (N) is in Group 15. When it forms a binary compound with a less electronegative element like a metal, it typically takes on an oxidation state of -3 (as the nitride ion, N\(^{3-}\)).
We can verify this by checking if the compound is neutral: (3 \(\times\) Mg's charge) + (2 \(\times\) N's charge) = (3 \(\times\) (+2)) + (2 \(\times\) (-3)) = +6 - 6 = 0. The assignments are correct.

Therefore, the oxidation state of Magnesium (Mg) changes from 0 in Mg\(_{(s)}\) to +2 in Mg\(_3\)N\(_2\).
Step 3: Final Answer:
The change in the oxidation state of Magnesium is from 0 to +2. This corresponds to option (A).