Complete and balance the following chemical equations:
(1) KMnO4 heat →
(2) Cr2O72− + 6 I− + 14 H+ →
(1) KMnO4 heat →
(2) Cr2O72− + 6 I− + 14 H+ →
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Solution and Explanation
(1): Thermal Decomposition of Potassium Permanganate (KMnO4)
- On heating, potassium permanganate (KMnO4) decomposes to form potassium manganate (K2MnO4), manganese dioxide (MnO2), and oxygen gas (O2).
- This reaction is used in laboratories as a source of oxygen.
The thermal decomposition reaction is:
2KMnO4 heat → K2MnO4 + MnO2 + O2
(2): Redox Reaction of Dichromate and Iodide in Acidic Medium
- Dichromate (Cr2O72−) acts as an oxidizing agent and oxidizes iodide (I−) to iodine (I2) in acidic medium.
- The chromium in dichromate is reduced from Cr6+ to Cr3+.
- The reaction follows the principles of redox balancing, maintaining charge and mass balance.
The balanced redox reaction is:
Cr2O72− + 6I− + 14H+ → 2Cr3+ + 3I2 + 7H2O
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