Which of the following compounds is NOT the correct product formed when the parent metals is heated in air?
Calcium oxide (CaO)
Sodium oxide (Na2O)
Copper (ll) oxide (CuO)
Tri-iron tetroxide (Fe3O4)
Aluminium oxide (Al2O3)
Explanation
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The compound that is **NOT** the correct product formed when the parent metal is heated in air from the options provided is:
**B. Sodium oxide (Na2O)**
When sodium is heated in air, it primarily forms **sodium peroxide (Na₂O₂)**, rather than sodium oxide (Na2O)¹. The other compounds listed are indeed the products formed when their respective metals are heated in air:
- **Calcium** reacts to form **calcium oxide (CaO)**.
- **Copper** reacts to form **copper (II) oxide (CuO)**.
- **Iron** can react to form **tri-iron tetroxide (Fe3O4)**, also known as magnetite.
- **Aluminium** reacts to form **aluminium oxide (Al2O3)**.
I just made my research now and I discovered that Myschool is indeed correct. While it is true that the primary product formed when sodium is heated in air is sodium peroxide(Na2O2), sodium oxide(Na2O) can be formed in a LIMITED supply of air, meaning that it can be formed by heating sodium in air, albeit limited. In contrast, iron(II) diiron(III) is only prepared by the action of steam on red hot iron. Iron(III) oxide is the main product formed when iron is heated in air. So the answer is indeed C.
To answer this, let’s look at how each metal reacts with air (oxygen) when heated, and whether the oxide listed is the correct product.
A. Calcium oxide (CaO)
• Calcium is a reactive metal.
• It reacts with oxygen to form CaO.
• Correct product.
B. Sodium oxide (Na₂O)
• Sodium reacts with oxygen, but it forms sodium peroxide (Na₂O₂) more readily in air, not just Na₂O.
• So Na₂O is not the typical product when sodium is heated in air.
• This is the incorrect product.
C. Copper(II) oxide (CuO)
• When copper is heated in air, it forms CuO (black) or sometimes a mixture of CuO and Cu₂O, depending on temperature.
• CuO is acceptable as a major product.
• Correct product.
D. Tri-iron tetroxide (Fe₃O₄)
• Iron forms Fe₃O₄ (a mixed oxide of Fe²⁺ and Fe³⁺) when heated in air.
• Correct product.
E. Aluminium oxide (Al₂O₃)
• Aluminium rapidly forms a protective layer of Al₂O₃ when exposed to air.
• Correct product.
Final Answer: B. Sodium oxide (Na₂O)
Because the actual product is sodium peroxide (Na₂O₂) when sodium is heated in air, not Na₂O.
myschool please make correction on this
the answer is B
Sodium react vigorously with air(oxygen) to form Sodium peroxide ( Na2O2) rather than Sodium oxide Na2O
Sodium oxide is not typically the product form when Sodium is heated in air
The answer shown is C, while the AI has proven the answer to be B and I chose B but I missed it.
E. Aluminium oxide (Al2O3) - Aluminium forms a protective oxide layer when exposed to air, preventing further reaction. Therefore, aluminium does not readily react with oxygen in the air to form aluminium oxide under normal conditions. This option seems to be incorrect.
the answer is E.
