Question

When potassium permanganate is heated to 513 K it forms

• A. Mn\(_2\)O\(_3\) and O\(_2\)
• B. MnO\(_2\) and K\(_2\)O
• C. Mn\(_2\)O\(_3\), MnO\(_2\) and K\(_2\)O
• D. K\(_2\)MnO\(_4\), MnO\(_2\) and O\(_2\)
• E. K\(_2\)MnO\(_4\) and O\(_2\)

Hint:

This is a common reaction used to prepare oxygen in the lab. The purple color of KMnO\(_4\) changes to the green color of K\(_2\)MnO\(_4\).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
This question asks for the products of the thermal decomposition of potassium permanganate (KMnO₄). This is a standard reaction in inorganic chemistry.
Step 2: Key Formula or Approach
The balanced chemical equation for the thermal decomposition of potassium permanganate is required. The reaction occurs at about 513 K (240 °C).
The unbalanced reaction involves KMnO₄ breaking down into potassium manganate (K₂MnO₄), manganese dioxide (MnO₂), and oxygen gas (O₂).
\[ \text{KMnO}_4(s) \xrightarrow{\Delta} \text{K}_2\text{MnO}_4(s) + \text{MnO}_2(s) + \text{O}_2(g) \] Step 3: Detailed Explanation
Let's balance the equation.
Starting with the metals, we have 1 K on the left and 2 K on the right. So we place a 2 in front of KMnO₄.
\[ 2\text{KMnO}_4(s) \xrightarrow{\Delta} \text{K}_2\text{MnO}_4(s) + \text{MnO}_2(s) + \text{O}_2(g) \] Now let's check the other atoms:
- Potassium (K): 2 on the left, 2 on the right. (Balanced) - Manganese (Mn): 2 on the left, 1 + 1 = 2 on the right. (Balanced) - Oxygen (O): 2 4 = 8 on the left. 4 + 2 + 2 = 8 on the right. (Balanced) The balanced chemical equation is: \[ 2\text{KMnO}_4(s) \xrightarrow{513 \text{ K}} \text{K}_2\text{MnO}_4(s) + \text{MnO}_2(s) + \text{O}_2(g) \] The products formed are potassium manganate (K₂MnO₄), manganese dioxide (MnO₂), and oxygen (O₂).
Step 4: Final Answer
The products of heating potassium permanganate are potassium manganate, manganese dioxide, and oxygen. This corresponds to option (D).