Question

If the freezing point of a 0.01 molal aqueous solution of a cobalt (iii) chloride ammonia complex (behaves as a strong electrolyte) is `-0.0558^(@)C`, What is the number of chloride (s) in the co-ordeination sphere of the complex `(K_(f)"of water "1.86" K kg mol"^(-1))`.

Answer 1

`DeltaT_(f)=ixxK_(f)xxm`
`i=(DeltaT_(f))/(K_(f)xxm)=((0.0558K))/((1.86 Km^(-1))xx(0.01m))=3`
The value of I indicates that in aqueous solution, the complex dissociates to give ions.
`[Co(NH_(3))_(5)CI]CI_(2)overset(("aq"))to[Co(NH_(3))_(5)CI]^(+)2CI^(-)`
This means that one chlorine atom is present in the cooedination sphere. For more details, consult Unit-9 (Co-ordination compounds).