Coordination Compounds - Result Question 3
####3. Cobalt (III) chloride forms several octahedral complexes with ammonia. Which of the following will not give test of chloride ions with silver nitrate at $25^{\circ} C$ ?
[2015]
(a) $CoCl_3 \cdot 4 NH_3$
(b) $CoCl_3 \cdot 5 NH_3$
(c) $CoCl_3 \cdot 6 NH_3$
(d) $CoCl_3 \cdot 3 NH_3$
Show Answer
Solution:
- (d) $CoCl_3 \cdot 3 NH_3$ will not give test for chloride ions with silver nitrate due to absence of ionisable chloride atoms.
$CoCl_3 \cdot 3 NH_3 \Rightarrow[Co(NH_3)_3 Cl_3]$
$[Co(NH_3)_3 Cl_3] \xrightarrow{AgNO_3}$ noppt
Secondary valence is fixed for a metal/ion. For $Co^{3+}$, it is six.
