Question

Alfred Werner (1866-1919) A Swiss chemist was the first to formulate his ideas about the
structure of coordination compounds. He prepared and characterized a large number of
coordination compounds and studied their physical and chemical behavior by simple
experimental techniques. Werner proposed the concept of a primary valence and a secondary
valence for a metal ion Binary compounds such as CCI,COCI, or P&Cl, have primary valence of
3.2 and 2 respectively. In a series compound of cobalt(III) chloride with ammonia, it was found
that some of the chloride ions could be precipitated as Agcion adding execess silver nitrate
solution in cold but some remained in solution
1 mol COCI, 6NH, (yellow)
gave 3 mol Agci
1 mol COCI, 5NH, (purple)
gave 2 mol Agci
1 mol COCI4NH (Green)
gave Imol AgCI
1 mol COCI, 4NH,(violet)
gave 1 mol AgCI
Page 3
(i) One mole of the complex compound Co(NH,), CI,,gives 3 moles of ions on dissolution in
water one mole of the same complex reacts with two moles of AgNO, solution to yield two
moles of AgCl(s). The structure of the compex is
a) (CO(NH,), C1]2NH
b) [CO(NH),C1,CINH
c) [Co(NH4), c]C, NH, . d) (CO (NH), CI]
(ü) When AgNO, is added to a solution of Co(NH), Cis, the precipitate of AgCl shows two
soluble chloride ions. This means
a) Two chloride atoms satisfy primary valency and one secondary valency
b) One chlorine atom satisfies primary as well as secondary velency
c) Three chlorine atom satisfy primary valency
d) Three chloride atoms satisfy secondary valency
(ii) Which one is most likely structure of CrCl6H.0 if 1/3 of total chloride of the compound
is precipitated by adding AgNO,
a) CCI.61,0
b) [Cr(1.0), (!](1,0),
c) [CHCI. (H20).]C12H20
d) (C-CI(H2O)]CI
, H,0
(iv) The Oxidation state of Crin (Cr(NH), Cl]' is
b) +1
d) +2
c) +3
a) 0
(OR)
(V) In Ni(CO), Oxidation number of Niis:​

Answer 1

Explanation:

secondary valency

b) One chlorine atom satisfies primary as well as secondary velency

c) Three chlorine atom satisfy primary valency

d) Three chloride atoms satisfy secondary valency

(ii) Which one is most likely structure of CrCl6H.0 if 1/3 of total chloride of the compound

is precipitated by adding AgNO,

a) CCI.61,0

b) [Cr(1.0), (!](1,0),

c) [CHCI. (H20).]C12H20

d) (C-CI(H2O)]CI

, H,0

(iv) The Oxidation state of Crin (Cr(NH), Cl]' is

b) +1

d) +2

c) +3

a) 0

(OR)