Q.21
Reaction of Na2SO3 with 2 equivalents of HCl produces a gas X.
Solution of X in water is acidic in nature. X is:
- O2
- Cl2
- SO2
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O₂: Oxygen gas is not produced; this reaction involves sulfite reduction, not oxidation to O₂.
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Cl₂: Chlorine gas requires oxidation of Cl⁻ (e.g., by strong oxidants like MnO₂), absent here; HCl acts only as a proton source.
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SO₂: Correct. Matches the reaction stoichiometry and acidic solution property (SO₂ + H₂O ⇌ H₂SO₃).
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H₂S: Hydrogen sulfide comes from sulfides (e.g., Na₂S + HCl), not sulfites; no S²⁻ present.H2S
Na₂SO₃ reacts with 2 equivalents of HCl to produce SO₂ gas, which forms an acidic aqueous solution due to its reaction with water.
Reaction Analysis
The balanced equation is Na₂SO₃ + 2HCl → 2NaCl + H₂O + SO₂↑. Sodium sulfite (Na₂SO₃), a source of SO₃²⁻ ions, reacts with acid (H⁺ from HCl) to release sulfur dioxide gas (SO₂), confirmed by multiple chemical sources. SO₂ dissolves in water to form sulfurous acid (H₂SO₃), making the solution acidic (pH < 7).
Option Breakdown
Introduction to Na2SO3 HCl Reaction Gas X SO2
In chemistry, the Na2SO3 HCl reaction with 2 equivalents produces gas X, identified as SO2, whose water solution is acidic—key for exams like GATE Life Sciences. This double displacement yields NaCl, H2O, and SO2↑, distinguishing it from other gases.
Step-by-Step Na2SO3 + HCl Mechanism
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SO₃²⁻ + 2H⁺ → H₂SO₃ → H₂O + SO₂ (decomposition).
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Full: Na₂SO₃ + 2HCl → 2NaCl + H₂O + SO₂.
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SO₂ hydrolyzes: SO₂ + H₂O ⇌ H⁺ + HSO₃⁻, confirming acidity.
Why Not Other Options in Na2SO3 HCl Reaction?
Option Reason Eliminated O₂ Requires oxidation, not acid protonation . Cl₂ No Cl⁻ oxidation here; HCl provides H⁺ only. H₂S From Na₂S, not Na₂SO₃ (oxidation state mismatch). SO₂ Matches gas evolution and acidic test perfectly . GATE Life Sciences Relevance
Mastering Na2SO3 HCl reaction gas X SO2 aids inorganic chemistry sections, emphasizing gas tests and acidity for competitive exams. Practice balancing for quick solves.
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