Question

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

Hint:

- 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.

Answer 1

(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