Chemistry

Coordination Compounds

Question:

Aqueous copper sulphate solution (blue in colour) gives: (i) a green precipitate with aqueous potassium fluoride and  (ii)a bright green solution with aqueous potassium chloride. Explain these experimental results.

Answer:

Aqueous CuS04 solution exists as [Cu(H20)4]S04 which has blue colour due to [Cu(H20)4]2+ ions.
(i) When KF is added, the weak H20 ligands are replaced by F ligands forming [CUF4]2- ions which is a green precipitate.
ncert-solutions-for-class-12-chemistry-coordination-compounds-10
(ii)When KCl is added, Cl ligands replace the weak H20 ligands forming [CuCl4]2- ion which has bright green colour.
ncert-solutions-for-class-12-chemistry-coordination-compounds-11

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Coordination Compounds

Q 1.

When 1 mol CrCl3.6H2O is treated with excess of AgNO3, 3 mol of AgCl are obtained. The formula of the complex is
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-6

Q 2.

What is meant by unidentate didentate and ambidentate ligands? Give two examples for each.

Q 3.

Assertion (A): [Cr(H2O)6]Cl2 and [Fe(H2O)6]Cl2 are reducing in nature. Reason (R): Unpaired electrons are present in their J-orbitals.

Q 4.

Calculate the overall complex dissociation equilibrium constant for the  Cu(NH3)42+  ion, given that β4  for this complex is 2.1 x  1013.

Q 5.

Write the IUPAC names of the following coordination compounds:
(i)[Co(NH3)6]Cl3
(ii)[Co(NH3)5Cl]Cl2
(iii)K3[Fe(CN)6l
(iv)K3lFe(C2O4)3]
(v)K2[PdCl4]
(vi)[Pt(NH3)2Cl(NH2CH3)]Cl

Q 6.

On the basis of crystal field theory explain why Co(III) forms paramagnetic octahedral complex with weak field ligands whereas it forms diamagnetic octahedral complex with strong field ligands.

Q 7.

A complex of the type [M(AA)2X2]n+ is known to be optically active. What does this indicate about the structure of the complex? Give one example of such complex.

Q 8.

The colour of the coordination compounds depends on the crystal field splitting. What will be the correct order of absorption of wavelength of
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-3

Q 9.

Magnetic moment of [MnCl4]2- is 5.92 BM. Explain giving reason.

Q 10.

Arrange following complex ions in increasing order of crystal field splitting energy (A0):
[Cr(Cl)6]3-, [Cr(CN)6]3-, [Cr(NH3)6]3+

Q 11.

What is meant by the chelate effect? Give an example.

Q 12.

Amongst the following, the most stable complex is:
(i) [Fe(H2O)6] (ii) [Fe(NH3)6]3+
(iii) [Fe(C2O4)3]3- (iv) [FeCl6]3-

Q 13.

CUSO4.5H2O is blue in colour while CuSO4 is colourless. Why?

Q 14.

In the following questions, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the following choices.
(a) Assertion and Reason both are true, Reason is the correct explanation of Assertion.
(b) Assertion and Reason both are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true, Reason is false.
(d) Assertion is false, Reason is true.

Assertion (A): Toxic metal ions are removed by the chelating ligands. Reason (R): Chelate complexes tend to be more stable.

Q 15.

[Fe(CN)6]4- and [Fe(H2O)6]2+ are of different cdlours in dilute solutions. Why?

Q 16.

What is meant by stability of a coordination compound in solution? State the factors which govern stability of complexes.

Q 17.

Which of the following options are correct for [Fe(CN)6]3- complex?
(a) d2sp3 hybridisation
(b) sp3d2  hybridisation
(c) Paramagnetic
(d) Diamagnetic

Q 18.

Which of the following complexes show linkage isomerism?
(a) [CO(NH3)5(NO2)]2+  (b) [CO(H2O)5CO]3+
(c) [Cr(NH3)5SCN]2+  (d) [Fe(en)2Cl2]+

Q 19.

Match the complex species given in Column I with the possible isomerism given in Column II and assign the correct code:
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-32

Q 20.

Indicate the complex ion which shows geometrical isomerism.
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-8

Q 21.

Why are low spin tetrahedral complexes not formed?

Q 22.

Discuss the nature of bonding in metal carbonyls.

Q 23.

Arrange the following complexes in the increasing order of conductivity of their solution:
[Co(NH3)3Cl3], [CO(NH3)4Cl2]Cl, [CO(NH3)6]C13, [Cr(NH3)5Cl]Cl2

Q 24.

What is the relationship between observed colour of the complex and the wavelength of light absorbed by the complex?

Q 25.

The hexaquomanganese(II) ion contains five unpaired electrons, while the hexacyano ion contains only one unpaired electron. Explain using Crystal Field Theory.

Q 26.

What is the coordination entity formed when excess of aqueons KCN is added to an aqueous solution of copper sulphate? Why is it that no precipitate of copper sulphide is obtained when H2S (g) is passed through this solution?

Q 27.

The stabilization of coordination compounds due to chelation is called the chelate effect. Which of the following is the most stable complex species?
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-7

Q 28.

Why do compounds having similar geometry have different magnetic moment?

Q 29.

Match the coordination compounds given in Column I with the central metal atoms given in Column II and assign the correct code:
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-27
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-28

Q 30.

Explain on the basis of valence bond theory that  [Ni(CN)4]2-  ion with square planar structure is diamagnetic and the[Ni(CN)4]2- ion with tetrahedral geometry is paramagnetic.

Q 31.

Amongst the following ions? Which one has the highest magnetic moment value:
(i) [Cr(H2O)6]3+
(ii) [Fe(H20)6]2+ (iii) [Zn(H20)6]2+

Q 32.

Give the electronic configuration of the following complexes on the basis of crystal field splitting theory.
[COF6]3-, [Fe(CN)6]4- and [Cu(NH3)6]2+.

Q 33.

Assertion (A): Linkage isomerism arises in coordination compounds containing ambidentate ligand.
Reason (R): Ambidentate ligand has two different donor atoms.

Q 34.

Using crystal field theory, draw energy level diagram, write electronic
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-38

Q 35.

Give evidence that  [Co(NH3)5Cl]S04  and [Co(NH3)5S04]Cl  are ionisation isomers.

Q 36.

Draw all the isomers (geometrical and optical) of
(i)[CoCl2(en)2]+
(ii)[Co(NH3) Cl (en)2]2+
(iii) [Co(NH3)2Cl2(en)]+

Q 37.

What is crystal field splitting energy? How does the magnitude of Δ0 decide the actual configuration of d-orbitals in a coordination entity?

Q 38.

Which of the following complexes are homoleptic?
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-16

Q 39.

Identify the correct statements for the behaviour of ethane-1, 2-diamine as a ligand.
(a) It is a neutral ligand (b) It is a didentate ligand
(c) It is a chelating ligand (d) It is a unidentate ligand

Q 40.

A coordination compound CrCl3.4H2O precipitates silver chloride when treated with silver nitrate. The molar conductance of its solution corresponds to a total of two ions. Write structural formula of the compound and name it.

Q 41.

Explain why [Fe(H2O)6]3+  has magnetic moment value of 5.92 BM whereas [Fe(CN)6]3- has a value of only 1.74 BM.

Q 42.

Name the type of isomerism when ambidentate ligands are attached to central metal ion. Give two examples of ambidentate ligands.

Q 43.

Match the complex ions given in Column I with the colours given in Column II and assign the correct code:
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-26

Q 44.

Why are different colours observed in octahedral and tetrahedral complexes for the same metal and same ligands?

Q 45.

Write the formulas for the following coordination compounds:
(i)Tetraamminediaquacobalt(IlI) chloride
(ii)Potassium tetracyanidonickelate(II)
(iii)Tris(ethanp-1,2-diamine) chromium(III) chloride
(iv)Amminebromidochloridonitrito-N- platinatc(II)
(v)Dichloridobis(ethane-l ,2-diamine) platinum (IV) nitrate
(vi)Iron(III)hexacyanidoferrate(II)

Q 46.

[Fe(H2O)6]3+is strongly paramagnetic whereas  [Fe(CN)6]3-is weakly paramagnetic. Explain.

Q 47.

Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heteroleptic.

Q 48.

Using IUPAC norms write the formulas for the following:
(i)Tetrahydroxozincate(Il)
(ii)Potassium tetrachloridopalladate (II)
(iii)Diamminedichlorido platinum (II)
(iv)Potassium tetracyanonickelate (II)
(v)Pentaamminenitrito-O-cobalt(III)
(vi)Ilexaamminccobalt (III) sulphate
(vii)Potassium tri(oxalato) chromate (III)
(yiii)Hexaammineplatinum (IV)
(ix)Tetrabromidocuprate(II)
(x) Pentaamminenitrito-N-cobalt (III)

Q 49.

Draw the structures of optical isomers of
(i) [Cr(C2O4)3]3-
(ii)[PtCI2(en)2]2+
(iii)[Cr(NH3)2CI2(en)]+

Q 50.

A solution of [Ni(H20)6]2+ is green but a solution of [Ni(CN)4]2-is colourless. Explain.