JEE Advance - Chemistry (2015 - Paper 1 Offline - No. 4)
If the freezing point of a 0.01 molal aqueous solution of a cobalt (III) chloride-ammonia complex(which
behaves as a strong electrolyte) is – 0.0558oC, the number of chloride(s) in the coordination sphere of the
complex is [Kf of water = 1.86 K kg mol–1 ]
Answer
1
Explanation
The depression in freezing point is given by
$$\Delta$$Tf = Kf $$\times$$ m $$\times$$ i
0.0558 = 1.86 $$\times$$ 0.01 $$\times$$ i
i = 3
Therefore, one mole of complex gives three moles of ions in solution.
Hence, the complex is [Co(NH3)5Cl]Cl2 and the number of Cl$$-$$ ions inside the coordination sphere is 1.
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