Question:medium

Complete and balance the following chemical equations:
(1) KMnO4 heat
(2) Cr2O72− + 6 I + 14 H+

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- KMnO$_4$ decomposition is a key reaction in the production of oxygen in labs. - Dichromate-Iodide reaction is a classic redox reaction where Cr$^{6+}$ is reduced, and I$^-$ is oxidized to I$_2$. - Always balance chemical equations by ensuring both mass and charge conservation.
Updated On: Jan 13, 2026
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Solution and Explanation

(1): Thermal Decomposition of Potassium Permanganate (KMnO4)

- Heating potassium permanganate (KMnO4) yields potassium manganate (K2MnO4), manganese dioxide (MnO2), and oxygen gas (O2).

- This reaction is utilized in laboratories as an oxygen source.

The thermal decomposition reaction is:

2KMnO4 heat → K2MnO4 + MnO2 + O2

(2): Redox Reaction of Dichromate and Iodide in Acidic Medium

- In an acidic medium, dichromate (Cr2O72−) oxidizes iodide (I) to iodine (I2).

- The chromium in dichromate is reduced from a +6 oxidation state to +3.

- This reaction adheres to redox balancing principles, maintaining both charge and mass conservation.

The balanced redox reaction is:

Cr2O72− + 6I + 14H+ → 2Cr3+ + 3I2 + 7H2O

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