Tag: coordination chemistry

Questions Related to coordination chemistry

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. $2,4$

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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.

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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

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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

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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.

Which of the following statement(s) is/are correct?

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

  1. Primary valency of the central metal of a complex is always satisfied by anions.

  2. Secondary valency of the central metal of a complex may be satisfied by either negative ions or neutral molecules.

  3. Species which show primary valencies in a complex compound can be precipitated out.

  4. None of the above

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Correct Option: A,B,C
Explanation:

In short the Werner's theory may be stated as follows:

  1. The central metal in a complex possesses two types of valencies, primary or ionizable valency and secondary valency or non-ionizable valency.
  2. While the primary valency of the metal is variable, the secondary valency has a fixed value. The primary valency refers to the oxidation state and the secondary valency to the coordination number of the metal.
  3. The primary valency is satisfied by only negative ions whereas the secondary valency either by anions or neutral molecules or both.
  4. The secondary valencies are directed in space towards fixed positions around the neutral atom.
Hence, options A, B and C are correct.

When $AgNO _3$ is added to a solution of $Co(NH _3) _5 Cl _3$, the precipitate of $AgCl$ shows two ionized chloride ions. This means:

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

  1. only two chlorine atoms satisfy primary valency and one secondary valency

  2. one chlorine atom satisfies primary as well as secondary valency

  3. two chlorine atoms satisfy primary valency

  4. three chlorine atoms satisfy secondary valency

Show answer
Correct Option: B,C
Explanation:

Option (B),(C) are correct.
When $AgNO _3$ is added to a solution of $Co(NH _3) _5 Cl _3$, the precipitate of $AgCl$ shows two ionized chloride ions.This means one chlorine atom satisfies primary as well as secondary valency and two chlorine atoms satisfy primary valency. Hence, $Co(NH _3) _5 Cl _3$, can be written as $[Co(NH _3) _5 Cl]Cl _2$,