Question

The primary valence and secondary valence of central metal ion and number of total ions produced in aqueous solution for \[K[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]\] complex respectively is__________.
a.) 3,4,2
b.) 4,4,2
c.) 3,6,2
d.) 3,6,1

Answer 1

Hint: In coordination chemistry primary valence is noting the oxidation of the metal and the secondary valence is the number of ions of molecules that are coordinated or bonded to the metal ion directly.

Complete step by step answer:
The given coordination complex is \[K[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]\].
The metal which is present in the complex is Cobalt, and ligands are \[\text{OX= OXALATE, }\]and \[N{{H}_{3}}=ammonia\].
Primary valence is nothing but the oxidation number of the metal in the given complex.
Step1: Overall charge:
The ionic form of the given complex is \[{{[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]}^{-1}}\]
From the ionic structure, it can be inferred that the overall charge of the complex is -1.
Step 2: Ligands and its charges:
The compounds contain one neutral ligand (\[N{{H}_{3}}=ammonia\]) and one negative ligand \[\text{OX= OXALATE}\].
The charge on the neutral ligand is “0”.
The charge on the negative ligand of one molecule -2. As there are 2 molecules its charge is -4.
Step 3: Charge of central metal ion
In the given complex, the central metal atom is cobalt.
Let us imagine the charge on cobalt is x.
The oxidation number of cobalt in \[K[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]\] is calculated as follows
x + (-4) + 0 = -1
x - 4 = -1
x = -1+4
x = 3
Thus the oxidation state of the Cobalt in \[K[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]\] is +3. Means primary valence is +3.
Coming to secondary valence there are four ligands directly attached to cobalt. So, the secondary valence is four.
The complex \[K[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]\] whenever dissolves in water gives two ions those are \[{{K}^{+}}\] and \[{{[Co{{(OX)}_{2}}{{(NH_3)}_{2}}]}^{-1}}\].
So, the total number of ions produced by the complex is two ions in the solution.
So, the correct option is A. 3, 4, 2.

Note: Don’t be confused with the terms primary valence, and secondary valence.
Primary valence is nothing but the oxidation state of a metal in the complex and secondary valence means number ligands attached directly to the metal in the coordination complex.