Q39 / 160 · AP EAMCET 2012 · Chemistry
A coordinate complex contains $\mathrm{Co}^{3+}, \mathrm{Cl}^{-}$and $\mathrm{NH}_3$. When dissolved in water, one mole of this complex gave a total of 3 moles of ions. The complex is
- A$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right] \mathrm{Cl}_3$
- Correct answerB$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2$
- C$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right] \mathrm{Cl}$
- D$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3 \mathrm{Cl}_3\right]$
Solution
When the complex dissolved in water, it gives three ions, which shows that two $\mathrm{Cl}^{-}$ions are present outside the coordination sphere.
$\therefore$ The formula of the complex is
$\begin{aligned} & {\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2} \\ & {\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}\right] \mathrm{Cl}_2 \stackrel{\text { Water }}{\longrightarrow} \underbrace{\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_5 \mathrm{Cl}^{2+}+2 \mathrm{Cl}^{-}\right.}_{3 \text { ion }}}\end{aligned}$
Hence, the correct answer is option: 'B'.