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Questions Related to chemistry

The primary valence of the metal ion is satisfied by :

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. neutral molecules

  2. positive ions

  3. negative ions

  4. all

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Correct Option: C
Explanation:

The primary or principal valency; this is the ionisable valency. 


A metal always gives electron and becomes positively charged that can be neutralized by bonding with negative ion only. In a coordination compound, the number of negative ions needed to satisfy the charge on the central metal ion is it's  primary valency.

Secondary valencies correspond to ____________ of the metal atom and are satisfied by ligands.

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. coordination number

  2. valency

  3. element

  4. molecules

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Correct Option: A
Explanation:

 Secondary valency corresponds to the coordination number of central metal atom or ion. This may be satisfied by either negative ions or neutral molecules called ligands.

 Ligands satisfying the secondary valencies are always shown in square brackets, i.e. they form the coordination sphere of the metal atom.


Hence,option A is correct.

$2.33$g of compound X(empirical formula $CoH _{12}N _4Cl _3)$ upon treatment with excess $AgNO _3$ solution produces $1.435$g of a white precipitate. The primary and secondary valences of cobalt in compound X, respectively, are.
[Given : Atomic mass: $Co=59, Cl=35.5, Ag=108$].

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $3, 6$

  2. $3, 4$

  3. $2, 4$

  4. $4, 3$

Show answer
Correct Option: A
Explanation:

Since $0.01$ mole of $X$ produces $0.01$ mole of $AgCl$,hence one $Cl^-$ is out of coordination sphere or complex is $[CO(NH _3) _4Cl _2]Cl$ AND HENCE $CO(3+)$,has $6$ coordination number

Several octahedral complexes are possible from combinations of $Co^{3+}, Cl^{-}$ and $NH {3}$. The correct statement(s) regarding the octahedral coordination entities having the formula .$[Co(NH _{3}) _{n}Cl _{6 - n}]^{(n - 3)+}$ with $n\geq 3$, is/ are____________.

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. At most six octahedral complexes are possible

  2. One of the complexes is homoleptic

  3. All the complexes are paramagnetic

  4. Some of the complexes dissociate in water to give $Co^{3+}$ and $Cl^{-}$ ions

Show answer
Correct Option: A,B
Explanation:

$[Co(NH _3) _nCl _{6-n}]^{(n-3)^+}$  $n\ge 3$

For $n=3,n=4,n=5,n=6$
For $n=6\Rightarrow [Co(NH _3) _6]^{3+}=$ is  homopletic due to all 6 same ligands.
For $n=5\Rightarrow [Co(NH _3) _6]^{2+}$
For $n=4\Rightarrow [Co(NH _3) _6]^+=$
For $n=3\Rightarrow [Co(NH _3) _6]$
Only $4$ octahedral complex are possible.
One of them is homoleptic.

In the separation of $Cu^{2+}$ and $Cd^{2+}$ in the second group of qualitative analysis of cations, tetraamine copper (ll) sulphate and tetraamine cadmium (ll) sulphate react with KCN to form corresponding cyano complexes. Which of the following pairs of complexes and their relative stability enables the separation of $Cu^{2+}$ and $Cd^{2+}$?

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $K _2[Cu(CN) _4]$ is less stable and $K _2[Cd(CN) _4]$ is more stable

  2. $K _3[Cu(CN) _4]$ is more stable and $K _2[Cd(CN) _4]$ is less stable
  3. $K _3[Cu(CN) _4]$ is less stable and $K _2[Cd(CN) _4]$ is more stable

  4. $K _2[Cu(CN) _4]$ is more stable and $K _2[Cd(CN) _4]$ is less stable

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Correct Option: B

Primary and secondary valency of platinum in the complex $[Pt(en) _{2}Cl _{2}]$ are:

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $4,6$

  2. $2,6$

  3. $4,4$

  4. $2,4$

Show answer
Correct Option: B,D
Explanation:

The Given complex $[Pt(en) _2Cl _2]$ The primary valence is its oxidation number i.e +2 and the secendory valency is its coordination number i.e 6 in this case.(The en ligand is bidentate, and Cl is monodentate).The second possibility  is that compound can exist as $[Pt(en) _2]Cl _2$ and hence the primary valency can also be +2 and  secondary valence is 4. Hence option B and D are correct

The Alsatian-Swiss chemist Alfred Werner pioneered the field of coordination chemistry in the late nineteenth century. At that time, a number of compounds of cobalt (III) chloride with ammonia were known, with general formula $CoCl _3.xNH _3$ $x=3\ to\ 6$
Treatment of these compounds with aqueous HCl acid did not remove the ammonia. However, treatment of the compounds with excess of $AgNO _3$ at 273 K gave white precipitate of AgCl in varying ratio depending on the structure. Also each complex had electrical conductivity of varying nature.
 
There is no reaction of the compound with aqueous HCl indicating that there is no free $NH _3$. Thus, $NH _3$ ligand is bonded to cobalt(III) by________ .
chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. Primary valency.

  2. Secondary valency.

  3. Both of these.

  4. None of these.

Show answer
Correct Option: B
Explanation:
Option (B) is correct.

Thus, $NH _3$ ligand is bonded to cobalt$(III)$ by secondary valency. Ammonia is present inside the coordination sphere and does not ionises while chloride ions present outside the sphere reacts with $AgNO _3$

$[Co(NH _3) _5Cl]Cl _2 + AgNO _3 \longrightarrow [Co(NH _3) _5Cl](NO _3) _2 + AgCl _2$

How many EDTA (ethylenediaminetetraacetic acid) molecules are required to make an octahedral complex with $ Ca^{2+} $?

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. six

  2. three

  3. one

  4. two

Show answer
Correct Option: C
Explanation:

An octahedral complex has 6 bonds around the central atom . One EDTA moledule complexes with one molecule of calcium cation to form octahedral complex.

which has the maximum conductivity in thier 0.1M solution?

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. A) $\left[ Co{ (NH } _{ 3 }) _{ 3 }{ Cl } _{ 3 } \right] $

  2. B) $\left[ Co({ NH } _{ 3 }) _{ 4 }Cl \right] { Cl } _{ 2 }$

  3. C) $\left[ Co({ NH } _{ 3 }) _{ 5 }Cl \right] { Cl } _{ 2 }$

  4. D) $\left[ Co({ NH } _{ 3 }) _{ 6 } \right] { Cl } _{ 3 }$

Show answer
Correct Option: D
Explanation:

The maximum conductivity is shown by that compound which have maximum ions on dissociation. Hence the compound $[Co(NH _3) _6]Cl _3$ have the maximum number of ions $[Co(NH _3) _6] + 3Cl^-$ = 4 ions and hence the correct answer is D.

The number of complexes that can be can be made with varying $NH _3$ ligands to satisfy primary and secondary valencies of platinum are:

Complex; [$PtCl _4\cdot xNH _3$]   

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. 5

  2. 3

  3. 4

  4. 2

Show answer
Correct Option: A
Explanation:
The correct answer is 5.
The number of complexes that can be can be made with $PtCl _4\cdot xNH _3$ are :
 
I. $[Pt(NH _3) _6]Cl _4$

II. $[Pt(NH _3) _5Cl]Cl _3$

III. $[Pt(NH _3) _4Cl _2]Cl _2$

IV: $ [Pt(NH _3) _3Cl _3]Cl$

V: $[Pt(NH _3) _2Cl _4]$

Option A is correct.