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Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET PDF Download

1. Manganate & Permanganate (MnO4- & MnO42-)

(i) Methods of Preparation

a) Preparation of Manganate (MnO42–) :

Some Important Compounds of Transition Elements | Chemistry Class 12 - NEETSome Important Compounds of Transition Elements | Chemistry Class 12 - NEET

In presence of KClO3 & KNO3 the above reaction is more faster because these two on decomposition provides O2 easily.

Manganate is also obtained when KMnO4 is boiled with KOH.

4 KMnO4  + 4KOH Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 4K2MnO4  + 2H2O + O2

b) Another Method of Preparation: 

3K2MnO4 + 2H2SO→ 2KMnO4 + MnO2 + 2K2SO+ 2H2O

or 3K2MnO4 + 2H2O + 4CO2 → 2KMnO4 + MnO2 + 4KHCO3

But in the above method Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET of Mn is lost as MnO2 but when oxidised either by Cl2or by O3

2K2MnO4 + Cl2 → 2KMnO4 + 2KCl                                     [Unwanted MnO2 does not form]

OR

2K2MnO4 + O3 + H2O → 2KMnO4 + 2KOH + O2

(ii) Properties : 

The above green solution is quite stable in alkali, but in pure water and in presence of acids, depositing MnO2 and giving a purple solution of permanganate.

3K2MnO4 + 2H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2KMnO4 + MnO2¯ +  4KOH

 purple                                     dark brown

Prob : =  Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET


(iii) Oxidising Properties of KMnO4 in Different Mediums

1. Oxidising Property of KMnO4 in Acidic Medium:

  • MnO4 + Fe +2 +  H+  → Fe +3 + Mn +2 + H2O
  • MnO4-  +I-  +H+→ Mn +2 + I2 + H2O
  • MnO4-  + H2O2 + H+  → Mn +2 + O2 + H2O
  • MnO4-  + SO2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Mn +2  +H2SO4
  • MnO4- + NO2-  +H+  → Mn +2 + NO3- + H2O
  • MnO4-  + H2C2O4 + H+  → Mn +2  +CO2  +H2O
  • MnO4-  + H2S → Mn+ + S¯ +H2O

(1) It is not a primary standard since it is difficult to get it in a high degree of purity and free from trances of MnO2.

(2) It is slowly reduced to MnO2 especially in presence of light or acid

4 MnO4-  +4 H+  → 4 MnO2  + 2H2O + 3O2

Hence it should be kept in dark bottles and standardise just before use.

(viii) 2 KMnO4  + 16 HCl → 2KCl + 5Cl2  + 8H2O + 2MnCl2

2. Oxidising Property of KMnO4 in Alkaline Medium :

2 MnO4-  + 2OH- → 2MnO42-  + H2O + O.
Then 2MnO42- + 2H2O → 2MnO2  + 4OH-  + 2O

  • 2KMnO4  + H2O + KI → 2MnO2 + 2KOH + KIO3
  • 2KMnO4  + 3HCO2K → 2MnO+ KHCO3  +2K2CO3 + H2O
  • 2KMnO4 + 3H2O2 → 2MnO2  + 2KOH + 2H2O + 3O2

3. Oxidising Property of KMnO4 in Neutral or weakly acidic solution:

(i) 2KMnO4  + 3 MnSO4 + 2H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 5 MnO2 + K2SO4  + 2H2SO4

or MnO4- + Mn+2  + 2H2O → 5MnO2 + 4H+

In absence of Zn+2 ions, some of the Mn+2 ion may escape, oxidation through the formation of insoluble MnII[MnIVO3] manganous permanganite.

(ii) 8 KMnO4 + 3Na2S2O3 + H2O → 8 MnO2  + 3 Na2SO4 + 3 S + 2 KOH


Conversion of Mn+2 to MnO4-

(i) PbO2 
(ii) Pb3O4  + HNO3 
(iii) Pb2O3
(iv) NaBiO3/H +
(v) (NH4)2S2O8 /H +
(vi) KIO4/H+

Heating effect : 2KMnO4 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET K2MnO4  + MnO2  + O2

2K2MNO4 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2K2MnO3 + O2

2. Silver Nitrate(AgNO3)

(i) Chemical Reactions

  Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

In the same way in presence of O2, Ag complexes with NaCN/KCN.

4 Ag + 8 KCN + 2H2O + O2 ⇒ 4K[Ag(CN)2] + 4KOH

(ii) Properties :

  1. It is called as lunar caustic because in contact with skin it produces burning sensation like that of caustic soda with the formation of finely divided silver (black colour)
  2. Thermal decomposition:
  3. Properties of AgNO3 : [Already done in basic radical]
  4. 6 AgNO3  +3I2  +3H2O → 5 AgI +AgIO3 + 6HNO3            (excess)
  5. Ag2SO4 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2Ag +SO2  +O2
  6. A(AgNO3) Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET white ppt appears quickly
  7. B(Na2S2O3) Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET It takes time to give white ppt.
  8. (vi) Ag2S2O3  +H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Ag2S +H2SO4  
  9. AgBr +AgNO3  Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET  AgBr¯ +KNO3                          (Pale yellow) ppt.

AgCl, AgBr, AgI (but not Ag2S) are soluble in Na2S2O3 forming [Ag(S2O3)2]-3 complexes

(iv) Heating effect :

2 AgNO3 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2AgNO2 + O2

2 AgNO3 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2Ag  2NO+ O2

(VIII)

Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET
Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

Ag2O +H2O→ 2Ag+ H2O +O2

K2S2O8  +2AgNO3  +2H2O → 2AgO +2KHSO4  +2HNO3

  • AgO supposed to be paramagnetic due to d9 configuration. But actually it is diamagnetic and exists as AgI[AgIIIO2]
  •  Reaction involved in developer: K2FeII(C2O4 )2  +AgBr → KFeIII(C2O4)2  +Ag¯ +KBr


3. Zinc Oxide (ZnO)

ZnO : It is called as phillospher's wool due to its wooly flock type appearance

(i) Preparation : 

  1. 2Zn + O2 → 2ZnO
  2. ZnCO3 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET ZnO +CO2
  3. 2Zn(NO3)Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2ZnO+ 4NO2  +O2
  4. Zn(OH)2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET ZnO +H2O

(ii) Purest ZnO : 

4ZnSO4  +4Na2CO3  +3H2O → ZnCO3.3Zn(OH)2¯ +  4Na2SO4  +3CO2
                                                                      Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

(iii) Properties :

  1. ZnO(cold) Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET ZnO(hot)       (white yellow)
  2. It is insoluble in water
  3. It sublimes at 400ºC.
  4. It is amphoteric oxide
    • ZnO+ 2HCl → ZnCl2  +H2O
    • ZnO+ H2SO4 → ZnSO4  +H2O
    • ZnO +2NaOH → Na2ZnO2  +H2O
    • ZnO → Zn by H2 & C
    • ZnO+ H2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Zn +H2O
    • ZnO+ C Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Zn+ CO
  5. It forms Rinmann's green with Co(NO3)2
    • 2Co(NO3)2 → 2CoO +4NO2  +O2
    • CoO +ZnO → CoZnO2 or CoO - ZnO
    • Rinmann's green

(iv) Uses : 

  1. As white pigment. It is superior than white lead because it does not turn into black
  2. Rinmann's green is used as green pigment
  3. It is used as zinc ointment in medicine

4. Zinc Chloride (ZnCl2)

(i) Preparation :

Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

Anhydrous ZnCl2 cannot be made by heating ZnCl2.2H2O because

ZnCl2.2H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Zn(OH)Cl +HCl +H2O

Zn(OH)Cl Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET ZnO +HCl

To get anh. ZnCl2 : Zn +Cl2 → ZnCl2

Zn +2HCl(dry) → ZnCl2  +H2

or Zn +HgCl2 → ZnCl2  +Hg

(ii) Properties : 

(i) It is deliquescent white solid (when anhydrous)

(ii) ZnCl2 + H2S → ZnS
                +NaOH → Zn(OH)2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Na2[Zn(OH)4]
                +NH4OH → Zn(OH)2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET [Zn(NH3)4]

 

(iii) Uses : 

  1. Used for impregnating timber to prevent destruction by insects
  2. As dehydrating agent when anhydrous
  3. ZnO. ZnCl2 used in dental filling

5.Zinc Sulphate (ZnSO4

(i) Preparation : 

Zn +dil. H2SO4 → ZnSO4 + H2

ZnO+ dil H2SO4 → ZnSO4 + H2O

ZnCO3 + dil H2SO4 → ZnSO4 + H2O+ CO2

ZnS +2O2 → ZnSO4

ZnS+ O2 → ZnO+ SO2

ZnS +4O3 → ZnSO4 + 4O2

(ii) Properties :

ZnSO4 . 7H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET ZnSO4 . 6H2O  Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

(iii) Uses : 

  1. It is in eye lotion
  2. Lithophone making (ZnS BaSO4) as white pigment.

6. Copper Oxide (CuO)

(i) Preparation : 

(i) CuCO3. Cu(OH)2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2CuO +H2O +CO2 (commercial process)

Malachite Green

(native Cu-carbonate)

(ii) 2Cu O2 → 2CuO & Cu2O +O2 → 2CuO

(iii) Cu(OH)2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET CuO +H2O

(iv) 2Cu(NO3)2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2CuO +4NO2  +O2

(ii) Properties :

  1. CuO is insoluble in water
  2. Readily dissolves in dil. acids
    • CuO +H2SO4 → CuSO4  +H2O
    • HCl → CuCl2
    • HNO3 → Cu(NO3)2
  3. It decomposes when, heated above 1100ºC
    4CuO → 2Cu2O +O2
  4. CuO is reduced to Cu by H2 or C under hot condition
    • CuO +C → Cu +CO­
    • CuO +H2 → Cu+ H2

7. Copper Chloride (CuCl2 )

(i) Preparation : 

 CuO+ 2HCl (conc.) → CuCl2  +H2O

Cu(OH)2.CuCO3  +4HCl → 2CuCl2  +3H2O +CO2

(i) It is crystallised as CuCl2. 2H2O of Emerald green colour

(ii) Dil. solution in water is blue in colour due to formation of [Cu(H2O)4] complex.

(iii) Conc. HCl or KCl added to dil. solution of CuCl2 the colour changes into yellow, owing to the formation of [CuCl4]2- .

(iv) The conc. aq. solution is green in colour having the two complex ions in equilibrium 2[Cu(H2O)4]Cl2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET [Cu(H2O)4] + [CuCl4]2- + 4H2O

(v) CuCl2 → CuCl by no. of reagents

(a) CuCl2  +Cu-turnings Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2CuCl

(b) 2CuCl2 + H2SO3 + H2O → 2CuCl+ 2HCl +2H2SO4

(c) 2CuCl2  +Zn/HCl → 2CuCl +ZnCl2

(d) CuCl2 + SnCl2 → CuCl +SnCl4

Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

CuI2 does not exist.

 CuCl2.2H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET CuCl2  + 2H2O


8. Copper Sulphate (CuSO4)

(i) Preparation : -

CuO + H2SO4(dil) → CuSO4  + H2O

Cu(OH)2  + H2SO4(dil) → CuSO4  + 2H2O

Cu(OH)2.CuCO3 + H2SO4(dil) → CuSO4+ 3H2O+ CO2

 Cu H2SO4 + O2 → CuSO4 + H2O [Commercial scale]

(Scrap)

Cu dil. H2SO4 → no reaction {Cu is below H in electrochemical series}

 

(i) It is crystallised as CuSO4.5H2O

(ii)  Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET
Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET

(iii) Revision with all others reagent


9. Ferrous Sulphate (FeSO4.7H2O)

(i) Preparation : 

  1. Scrap Fe + H2SO4    (dil.) → FeSO4  + H2­
  2. From Kipp's waste
    FeS + H2SO4 (dil.) → FeSO4  + H2
  3. FeS2 + 2H2O + Some Important Compounds of Transition Elements | Chemistry Class 12 - NEETO2 → FeSO4 + H2SO4

  4. (ii) Properties : 

(i) It undergoes aerial oxidation forming basic ferric sulphate

4FeSO4  + H2O + O2 → 4Fe(OH)SO4

(ii) FeSO4.7H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET FeSO4 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Fe2O3  +SO2  +SO3

     anh.white

(iii) Aq. solution is acidic due to hydrolysis

FeSO4  + 2H2O Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET Fe(OH)2  + H2SO4   (weak base

 (iv) It is a reducing agent

(a) Fe2+  + MnO4- + H+  → Fe3++Mn2+ + H2O

(b) Fe +Cr2O72-  +H+  → Fe3+  +Cr3 +  +H2O

(c) Au3+  + Fe2+ → Au+ Fe3+

(d) Fe2+   +HgCl2 → Hg2Cl2¯ +Fe3+          (white ppt.)

(v) It forms double salt. 

Example (NH4)2SO4. FeSO4.6H2O


10. FeO(Black) 

(i) Preparation : 

FeC2O4 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET FeO +CO +CO2

(ii) Properties :

 It is stable at high temperature and on cooling slowly disproportionates into

Fe3O4 and iron.

4FeO → Fe3O4  +Fe


11. Ferrous Chloride(FeCl2 )

(i) Preparation :

                Fe+ 2HCl Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET FeCl2  +H2                             

or           2FeCl3 + H2 Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET 2 FeCl2  +2HCl


(ii) Properties : 

  1. It is deliquescent in air like FeCl3
  2. It is soluble in water, alcohol and ether also because it is sufficiently covalent in nature.
  3. It volatilises at about 1000ºC and vapour density indicates the presence of Fe2Cl4. Above 1300ºC density becomes normal
  4. It oxidises on heating in air
    12FeCl2 + 3O2 → 2Fe2O3  +8FeCl3
  5. Hevolves on heating in steam
    3FeCl2  +4H2O → Fe3O4  +6HCl +H2
  6. It can exist as different hydrated form
    • FeCl2.2H2O → Colourless
    • FeCl2.4H2O → pale green
    • FeCl2.6H2O → green
The document Some Important Compounds of Transition Elements | Chemistry Class 12 - NEET is a part of the NEET Course Chemistry Class 12.
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FAQs on Some Important Compounds of Transition Elements - Chemistry Class 12 - NEET

1. What are some important compounds of transition elements?
Ans. Some important compounds of transition elements include manganate & permanganate, silver nitrate, zinc oxide, zinc chloride, zinc sulphate, copper oxide, copper chloride, copper sulphate, ferrous sulphate, and iron oxide.
2. What is the chemical formula of silver nitrate?
Ans. The chemical formula of silver nitrate is AgNO3.
3. What are the uses of zinc oxide?
Ans. Zinc oxide is commonly used in sunscreen, ointments, baby powder, and as a pigment in paints.
4. How is copper sulphate commonly used?
Ans. Copper sulphate is commonly used as an agricultural fungicide and herbicide, as well as in the preparation of Bordeaux mixture for plant disease control.
5. What is the significance of ferrous sulphate?
Ans. Ferrous sulphate is commonly used as a dietary supplement for iron deficiency and as a reducing agent in chemical reactions.
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