48. Given below are two statements:

Statement-I: Heating NaCl with concentrated H₂SO₄ and MnO₂ results in oxidation of Mn.

Statement-II: Heating NaI with concentrated H₂SO₄ and MnO₂ results in reduction of Mn.

In light of the above statements, choose the most appropriate answer from the options given below:

1. Statement-I is correct but Statement-II is incorrect.
2. Statement-I is incorrect but Statement-II is correct.
3. Both Statement-I and Statement-II are correct.
4. Both Statement-I and Statement-II are incorrect.

Answer: (2) Statement-I is incorrect but Statement-II is correct.

Reactions of Halide Salts with MnO₂ and Concentrated H₂SO₄

These are important for Salt Analysis, p-Block (Halogens), and Redox Reactions.

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1. NaCl + MnO₂ + Conc. H₂SO₄

Step 1: Formation of HCl

$$2NaCl + H_2SO_4 \rightarrow Na_2SO_4 + 2HCl$$

Step 2: Oxidation of HCl by MnO₂

$$MnO_2 + 4HCl \rightarrow MnCl_2 + Cl_2 + 2H_2O$$

Overall Reaction

$$2NaCl + MnO_2 + 2H_2SO_4 \rightarrow Cl_2 + MnSO_4 + Na_2SO_4 + 2H_2O$$

Observation: Greenish-yellow chlorine gas evolved.

2. NaBr + MnO₂ + Conc. H₂SO₄

Step 1: Formation of HBr

$$2NaBr + H_2SO_4 \rightarrow Na_2SO_4 + 2HBr$$

Step 2: Oxidation of HBr

$$MnO_2 + 4HBr \rightarrow MnBr_2 + Br_2 + 2H_2O$$

Overall Reaction

$$2NaBr + MnO_2 + 2H_2SO_4 \rightarrow Br_2 + MnSO_4 + Na_2SO_4 + 2H_2O$$

Observation: Reddish-brown bromine vapours evolved.

Step 1: Formation of HI

$$2NaI + H_2SO_4 \rightarrow Na_2SO_4 + 2HI$$

Step 2: Oxidation of HI

$$MnO_2 + 4HI \rightarrow MnI_2 + I_2 + 2H_2O$$

Overall Reaction

$$2NaI + MnO_2 + 2H_2SO_4 \rightarrow I_2 + MnSO_4 + Na_2SO_4 + 2H_2O$$

Observation: Violet iodine vapours evolved.

Reactions of Halide Salts with MnO₂ and Concentrated H₂SO₄

These are important for Salt Analysis, p-Block (Halogens), and Redox Reactions.

Memory Trick

Cl → Green, Br → Brown, I → Viole

NEET Shortcut

Halide	Gas/Vapour Produced	Colour
Cl⁻	Cl₂	Greenish-yellow
Br⁻	Br₂	Reddish-brown
I⁻	I₂	Violet

Memory Trick:

Cl → Green, Br → Brown, I → Violet