Question

When Magnesium (Mg) burn in air, we get Magnesium ____ .

• A. Hydroxide
• B. Carbide
• C. Oxide
• D. Peroxide

Hint:

Burning usually means reacting with oxygen from the air. When Magnesium (Mg) burns, it reacts with Oxygen (\(O_2\)) to form Magnesium Oxide (MgO). \[ 2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO} \] This reaction produces a very bright white light. (Magnesium can also react with nitrogen in the air to form magnesium nitride, but the oxide is the main product from "burning").

Answer 1

The Correct Option is C

Concept: Burning is a chemical process, typically a rapid reaction between a substance with an oxidant, usually oxygen, to produce heat and light. When a metal like magnesium burns in air, it primarily reacts with the oxygen component of the air. Step 1: Reaction of Magnesium with Oxygen Magnesium (Mg) is a reactive metal. When it burns in air, it reacts vigorously with oxygen (\(O_2\)) from the air to form magnesium oxide (MgO). This reaction is characterized by a bright white flame. The balanced chemical equation for this reaction is: \[ 2\text{Mg}(s) + \text{O}_2(g) \rightarrow 2\text{MgO}(s) \] Magnesium oxide is a white powdery solid. Step 2: Consider other possible reactions Air is primarily composed of nitrogen (\(\text{N}_2\), about 78%) and oxygen (\(\text{O}_2\), about 21%). Magnesium can also react with nitrogen at high temperatures (like those achieved during burning) to form magnesium nitride (\(\text{Mg}_3\text{N}_2\)). \[ 3\text{Mg}(s) + \text{N}_2(g) \rightarrow \text{Mg}_3\text{N}_2(s) \] So, when magnesium burns in air, both magnesium oxide and some magnesium nitride are formed. However, the primary product due to reaction with oxygen (combustion) is magnesium oxide. The question asks what "Magnesium ___" we get, implying a compound of magnesium. Step 3: Analyzing the options
(1) Hydroxide (Magnesium Hydroxide, \(\text{Mg(OH)_2\)):} Magnesium hydroxide is formed when magnesium oxide reacts with water, or magnesium reacts with hot water/steam. It's not the direct product of burning magnesium in air alone.
(2) Carbide (Magnesium Carbide, e.g., \(\text{MgC}_2\) or \(\text{Mg}_2\text{C}_3\)): Formed by reaction of magnesium with carbon or hydrocarbons at very high temperatures. Not a primary product of burning in air.
(3) Oxide (Magnesium Oxide, MgO): This is the primary product formed when magnesium burns by reacting with oxygen in the air.
(4) Peroxide (Magnesium Peroxide, \(\text{MgO}_2\)): Magnesium typically forms the simple oxide (MgO) upon combustion. While magnesium peroxide exists, it's not the common product of burning Mg in air. Given the context of "burning in air," the principal reaction is with oxygen to form the oxide. The question is simplified to the most common product. Therefore, when Magnesium (Mg) burns in air, we primarily get Magnesium Oxide.