Question

Aqueous solution of Cocl3, 6NH3, upon addition
with AgNO3, produces 3 moles white precipitate.
Primary and secondary valency of metal in this
complex is
(1) 3,6
(2) 2,6
(3) 3,3
(4) 6,4
​

Answer 1

Answer:3,6

Explanation:nh3 has no oxidation state so O.S of cocl3 is 3....so primary valence 3 and there is 6 nh3 so secondary valence 6

Answer 2

Answer:

For CoCl₃.6NH₃ the primary valency of Co metal is equal to 3 and the secondary valency is equal to 6.

Explanation:

• The primary valency of metal determined the oxidation state. It can be satisfied by anions.
• The secondary valency of Co is determined the coordination number. Secondary valency is satisfied by both anions as well as neutral molecules.

• On the addition of 3 moles of AgNO₃ in CoCl₃.6NH₃ we get

          $CoCl_{3}.6NH_{3} +AgNO_{3}$    →   $[Co(NH_{3})_{6}]^{3+}+3AgCl$

Therefore three chlorine satisfied the primary valency and lies outside the coordination sphere. The six NH₃ satisfied the secondary valency and lies inside the coordination sphere of complex.

Therefore the option (1) is correct.