Given below are two statements: Statement-I: The gas liberated on warming a salt with dil H₂SO₄, turns a piece of paper dipped in lead acetate into black, it is a confirmatory test for sulphide ion. Statement-II: In statement-I the colour of paper turns black because of formation of lead sulphite. In the light of the above statements, choose the most appropriate answer from the options given below:

Solution & Explanation

Related Formula
Na₂S + H₂SO₄ arrow Na₂SO₄ + H₂S (CH₃COO)₂Pb + H₂S arrow PbS + 2CH₃COOH
Core Logic

When a salt containing sulphide is warmed with dilute H₂SO₄, H₂S gas is evolved. H₂S gas turns lead acetate paper black due to the formation of lead sulphide (PbS), not lead sulphite. Thus, Statement I is correct, but Statement II is incorrect.

Pattern Recognition

Lead acetate paper test is standard for H₂S gas, forming black PbS. Always watch out for the trap suffix: sulphite (SO₃²⁻) vs sulphide (S²⁻).

Chapter Mix

Class 11 Chemistry: Qualitative Analysis Class 11 Chemistry: p-Block Elements

Reference Study Guides

Qualitative Analysis

More Qualitative Analysis Previous-Year Questions — Page 2

Q64 jee_main_2024_31_jan_morning Precipitate Colors
The compound that is white in color is
  • A. ammonium sulphide
  • B. lead sulphate
  • C. lead iodide
  • D. ammonium arsinomolybdate

Solution

Core Logic

Analyzing the colors of the given salts: Lead sulphate (PbSO₄) is white. Ammonium sulphide ((NH₄)₂S) is soluble/colorless in solution. Lead iodide (PbI₂) is bright yellow. Ammonium arsinomolybdate is yellow.

Chapter Mix

Class 12 Chemistry: Salt Analysis

Q81 jee_main_2024_31_jan_morning Anion Identification
Molar mass of the salt from NaBr, NaNO₃, KI and CaF₂ which does not evolve coloured vapours on heating with concentrated H₂SO₄ is ________ g mol⁻¹. (Molar mass in g mol⁻¹: Na: 23, N: 14, K: 39, O: 16, Br: 80, I: 127, F: 19, Ca: 40)
Numerical Answer. Answer: 78 to 78

Solution

Step 1: Analyzing the reactions with Concentrated H2SO4

NaBr conc. H₂SO₄ Br₂ (Reddish-brown vapour evolves) NaNO₃ conc. H₂SO₄ NO₂ (Brown vapour evolves) KI conc. H₂SO₄ I₂ (Violet vapour evolves) CaF₂ conc. H₂SO₄ HF (Colorless vapour evolves)

Thus, CaF₂ does not evolve colored vapours.

Step 2: Calculating Molar Mass

Molar mass of CaF₂: Ca = 40

F₂ = 2 × 19 = 38 Molar mass = 40 + 38 = 78 g/mol
Chapter Mix

Class 12 Chemistry: Salt Analysis

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)