Chemistry

Coordination Compounds

Question:

FeS04 solution mixed with (NH4)2SO4solution  in 1:1 molar ratio gives the test of,Fe2+ion but CuSO4solution mixed with aqueous ammonia in 1:4 molar ratio does not give the test of Cu2+ ion. Explain why.  

Answer:

FeSO4 solution mixed with (NH4),S04 solution in 1 : 1 molar ratio forms a double salt, FeS04 (NH4)2SO4-6H2O (Mohr's salt) which ionizes in the solution to give Fe2+ions. Hence it gives the tests of Fe2+ ions. CuSO4 solution mixed with aqueous ammonia in 1:4 molar ratio forms a complex salt, with the formula [CU(NH3)4]SO4. The complex ion [Cu(NH3)4]2+ does not ionize to give Cu2+ ions. Hence, it does not give the tests of Cu2+ ion.

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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.

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

Q 6.

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

Q 7.

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 8.

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

Q 9.

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 10.

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 11.

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 12.

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

Q 13.

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

Q 14.

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 15.

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 16.

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

Q 17.

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 18.

Write all the geometrical isomers of [Pt(NH3)(Br)(Cl) (Py)] and how many of these will exhibit optical isomerism?

Q 19.

Draw figure to show the splitting of d-orbitals in an octahedral crystal field.

Q 20.

How many ions are produced from the complex Co(NH3)6Cl2 in solution?
(i) 6
(ii) 4
(iii)3
(iv)2

Q 21.

Why do compounds having similar geometry have different magnetic moment?

Q 22.

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 23.

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 24.

Explain the bonding in coordination compounds in terms of Werner's postulates.

Q 25.

What will be the correct order for the wavelengths of absorption in the visible region for the following:[Ni(NO2)6]4-, [Ni(NH3)6]2+, [Ni(H20)6]2+?

Q 26.

Assertion (A): Complexes of MX6 and MX5L type (X and L are unidentate) do not show geometrical isomerism.
Reason (R): Geometrical isomerism is not shown by complexes of coordination number 6.

Q 27.

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

Q 28.

Discuss the nature of bonding in metal carbonyls.

Q 29.

Which of the following complex formed by Cu2+ ions is most stable?
ncert-exemplar-problems-class-12-chemistry-coordination-compounds-1

Q 30.

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 31.

Identify the optically active compounds from the following:
(a) [Co(en)3]3+  (b) trans-[Co(en)2Cl2]+
(c) cis-[Co(en)2Cl2]+ (d) [Cr(NH3)5Cl]

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.

Why do compounds having similar geometry have different magnetic moment?

Q 34.

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

Q 35.

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 36.

CoSO4Cl.5NH3 exists in two isomeric forms ‘A' and ‘B'. Isomer ‘A' reacts with AgNO3 to give white precipitate, but does not react with BaCl2. Isomer ‘B' gives white precipitate with BaCl2 but does not react with AgNO3. Answer the following questions.
(i) Identify A' and B' and write their structural formulas.
(ii) Name the type of isomerism involved.
(iii) Give the IUPAC name of A' and B'.

Q 37.

[NiCl4]2- is paramagnetic while [Ni(CO)4]  is diamagnetic though both are tetrahedraL Why?

Q 38.

Predict the number of unpaired electrons in the square planar [Pt(CN)4]2- ion.

Q 39.

Specify the oxidation numbers of the metals in the following coordination entities:
(i) [Co(H2O)(CN)(en)2]2+ (ii) [CoBr2(en)2]+ (iii) [PtCl4]2-  (iv) K3[Fe(CN)6] (v) [Cr(NH3)3CI3]

Q 40.

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.

Q 41.

Discuss briefly giving an example in each case the role of coordination compounds in:(i)biological systems (iii) analytical chemistry (ii)medicinal chemistry and (iv) extraction/ metallurgy of metals.

Q 42.

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 43.

The oxidation number of cobalt in K[Co(CO)4] is
(i)+1
(ii)+3
(iii)-1
(iv)-3

Q 44.

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

Q 45.

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 46.

Why are low spin tetrahedral complexes not formed?

Q 47.

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

Q 48.

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 49.

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

Q 50.

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