InterviewSolution
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InterviewSolution
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A metal complex having composition Cr(NH_(3))_(4)Cl_(2)Br has been isolated in two forms A and B. The form A reacts with AgNO_(3) to give a white precipitate readily soluble in dilute aqueous ammonia, whereas Bgives a yellow precipitate soluble in concentrated ammonia. (i) Write the formulae of A and B. (ii) State hybridisation of chromium in each. (iii) Calculate their magnetic moments for each (spin-only value). (iv) Calculate the EAN for both. (v) Will they conduct electricity or not. (vi) Write the formula of the complexes formed when the precipitates dissolve in aqueous ammonia & the concentrated ammonia respectively. |
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Answer» Solution :`(i) [Cr(NH_(3))_(4)CLBR]Cl overset(aq)iff [Cr(NH_(3))_(4)ClBr]^(+)+Cl^(-),Ag^(+)+Cl^(-) to AgCl DARR`(white), soluble in dilute `NH_(3)`. `[Cr(NH_(3))_(4)Cl_(2)]Br overset(aq)iff [Cr(NH_(3))_(4)Cl_(2)]^(+) +Br^(-),Ag^(+)+Br^(-) to AGBR darr`(yellow), soluble in conc. `NH_(3)`. So , `A=[Cr(NH_(3))_(4)ClBr]Cl and B=[Cr(NH_(3))_(4)Cl_(2)]Br`. (ii) In both complexes chromium is in +3 oxidation state. Chromium with `3d^(3)` configuration has 3 unpaired electrons with weak field as well as strong field as well as strong field ligand. So, the hybridisation scheme is as follow :  (III) `mu=SQRT(n(n+2))=sqrt(15)` (iv) EAN=24-3+12=22 (v) Yes, both have two ions per formula unit. `(vi) AgCl+2NH_(3) iff [Ag(NH_(3))_(2)]Cl,AgBr+2NH_(3)iff[Ag(NH_(3))_(2)]Br` |
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