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COMEDK · Chemistry · 24. Coordination Compounds

An aqueous solution of \(\mathrm{CrCl}_3 .6 \mathrm{H}_2 \mathrm{O}\) (Molar mass \(=266.5 \mathrm{~g} / \mathrm{mol}\) ) containing 2.665 g of the solute after processing, when treated with excess of \(\mathrm{AgNO}_3\) gave 2.87 g of AgCl (Molar mass of \(\mathrm{AgCl}=143.5 \mathrm{~g} / \mathrm{mol}\) ) Choose the correct formula of the compound which give these results.

  1. A \(\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_3 \mathrm{Cl}_3\right] \cdot 3 \mathrm{H}_2 \mathrm{O}\)
  2. B \(\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2 \cdot \mathrm{H}_2 \mathrm{O}\)
  3. C \(\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_4 \mathrm{Cl}_2\right] \mathrm{Cl} .2 \mathrm{H}_2 \mathrm{O}\)
  4. D \(\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right] \mathrm{Cl}_3\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2 \cdot \mathrm{H}_2 \mathrm{O}\)

Step-by-step Solution

Detailed explanation

The number of moles of the complex \(\mathrm{CrCl}_3 \cdot 6\mathrm{H}_2\mathrm{O}\) is calculated as: Moles of complex \(= \dfrac{2.665 \text{ g}}{266.5 \text{ g/mol}} = 0.01 \text{ mol}\). The number of moles of \(\mathrm{AgCl}\) precipitated is calculated as: Moles of…