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Question #44561

Difficulty: 8/10 | 🟢 Free

The Question

A coordination compound with the empirical formula \ceCrCl3⋅6H2O\ce{CrCl3 \cdot 6H2O} exists as three distinct hydrate isomers (A, B, and C). At 298 K298 \text{ K}, the limiting molar conductivity (Λm∘\Lambda_m^\circ) of isomer B in aqueous solution is found to be 258.0 S cm2 mol−1258.0 \text{ S cm}^2 \text{ mol}^{-1}.

Given the limiting ionic conductivities at 298 K298 \text{ K}: λ∘(\ceCl−)=76.3 S cm2 mol−1\lambda^\circ(\ce{Cl^-}) = 76.3 \text{ S cm}^2 \text{ mol}^{-1} λ∘([\ceCr(H2O)6]3+)=156.0 S cm2 mol−1\lambda^\circ([\ce{Cr(H2O)6}]^{3+}) = 156.0 \text{ S cm}^2 \text{ mol}^{-1} λ∘([\ceCr(H2O)5Cl]2+)=105.4 S cm2 mol−1\lambda^\circ([\ce{Cr(H2O)5Cl}]^{2+}) = 105.4 \text{ S cm}^2 \text{ mol}^{-1} λ∘([\ceCr(H2O)4Cl2]+)=53.7 S cm2 mol−1\lambda^\circ([\ce{Cr(H2O)4Cl2}]^{+}) = 53.7 \text{ S cm}^2 \text{ mol}^{-1}

A 200 mL200 \text{ mL} portion of a 0.05 M0.05 \text{ M} aqueous solution of isomer B is treated with excess \ceAgNO3(aq)\ce{AgNO3(aq)}. Separately, a 0.01 mol0.01 \text{ mol} solid sample of isomer B is placed in a desiccator over concentrated \ceH2SO4\ce{H2SO4} until a constant weight is achieved.

What is the mass of the \ceAgCl\ce{AgCl} precipitate formed, and what is the mass loss due to dehydration of the solid sample, respectively? (Given molar masses in g mol−1\text{g mol}^{-1}: \ceAg=108.0\ce{Ag} = 108.0, \ceCl=35.5\ce{Cl} = 35.5, \ceH2O=18.0\ce{H2O} = 18.0)

Options

  • A.

    2.87 g2.87 \text{ g} and 0.18 g0.18 \text{ g}

  • B.

    4.31 g4.31 \text{ g} and 0.00 g0.00 \text{ g}

  • C.

    1.44 g1.44 \text{ g} and 0.36 g0.36 \text{ g}

  • D.

    2.87 g2.87 \text{ g} and 1.08 g1.08 \text{ g}

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Explanation

How the Examiner Thinks

Numerical_Precision

Improve calculation stamina and avoid rounding errors in high-stakes competitive examinations.

Concepts Behind This Question

Coordination Isomerism|Kohlrausch Law Infinite Dilution|Stoichiometric Coefficient Division

Why This Question Is Tricky

Common Mistakes

The problem tests the intersection of Kohlrausch's Law and Werner's Coordination Theory (Hydrate Isomerism).

The 'Hidden Variable' is the structural distinction between coordinated water (inside the coordination sphere) and lattice water (outside the sphere).

Students often fall into the trap of assuming all water molecules are lost during desiccation (Option D) or misidentifying the isomer by ignoring the stoichiometric multipliers (ν+\nu_+ and ν−\nu_-) in Kohlrausch's Law, leading to incorrect precipitation masses (Options B and C).

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterCoordination Compounds - Class 12
ConceptCoordination Isomerism
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree