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A 0.01 molal solution of a cobalt(III) chloride-ammonia complex, which dissociates completely, has a freezing point of -0.0558°C. Based on this data, how many chloride ions are present within the coordination sphere of the complex? [Kf for water = 1.86 K kg mol⁻¹]
- One
- Two
- Three
- Four
Correct answer: One
Solution
The freezing point depression is related to the van 't Hoff factor (i), which indicates the number of particles the complex dissociates into. Using the formula ΔTf = i × Kf × m, the calculated i corresponds to one chloride ion being inside the coordination sphere.
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Group-I:
(I) [Cr(CN)₆]³⁻
(II) [RuCl₆]²⁻
(III) [Cr(H₂O)₆]²⁺
(IV) [Fe(H₂O)₆]²⁺
Group-II:
(P) The t₂g orbitals are occupied by 4 electrons.
(Q) The spin-only magnetic moment is 4.9 BM.
(R) Forms a low-spin complex.
(S) The metal ion has an oxidation state of +4.
(T) The complex is a d⁴ species.
Given: Chromium (Cr) has an atomic number of 24, Ruthenium (Ru) has an atomic number of 44, and Iron (Fe) has an atomic number of 26.
Choose the correct pairing of Group-I with Group-II.
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