Manganate and Permanganate Class 12 Notes | EduRev

Chemistry Class 12

Created by: Mohit Rajpoot

Class 12 : Manganate and Permanganate Class 12 Notes | EduRev

The document Manganate and Permanganate Class 12 Notes | EduRev is a part of the Class 12 Course Chemistry Class 12.
All you need of Class 12 at this link: Class 12

Manganate & Permanganate

Preparation of Manganate (MnO42–):–

Manganate and Permanganate Class 12 Notes | EduRev
Manganate and Permanganate Class 12 Notes | EduRev

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 Manganate and Permanganate Class 12 Notes | EduRev 4K2MnO4  2H2O O2

Props : 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 + 2H2Manganate and Permanganate Class 12 Notes | EduRev 2KMnO4 + MnO2¯ +  4KOH

                                   purple      drak brown

Prob : Manganate and Permanganate Class 12 Notes | EduRev

Prove that MnO42- will disproportionate in acidic medium.

Another Method of Prepn.: 3K2MnO4 + 2H2SO→ 2KMnO4 + MnO2 + 2K2SO+ 2H2O

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

But in the above method Manganate and Permanganate Class 12 Notes | EduRev 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

Oxidising Prop. of KMnO4 : (in acidic medium)

(i) MnO4 + Fe +2 +  H+  → Fe +3 + Mn +2 + H2O

(ii) MnO4-  +I-  +H+→ Mn +2 + I2 + H2O

(iii) MnO4-  + H2O2 + H+  → Mn +2 + O2 + H2O

(iv) MnO4-  + SO2 Manganate and Permanganate Class 12 Notes | EduRev Mn +2  +H2SO4

(v) MnO4- + NO2-  +H+  → Mn +2 + NO3- + H2O

(vi) MnO4-  + H2C2O4 + H+  → Mn +2  +CO2  +H2O

(vii) 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

Oxidising Prop. of KMnO4 in alk. medium :

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

(i) 2KMnO4  + H2O + KI → 2MnO2 + 2KOH + KIO3

(ii) 2KMnO4  + 3HCO2K → 2MnO+ KHCO3  +2K2CO3 + H2O

(iii) 2KMnO4 + 3H2O2 → 2MnO2  + 2KOH + 2H2O + 3O2

Oxidising Prop. in neutral or weakly acidic solution:

(i) 2KMnO4  + 3 MnSO4 + 2H2Manganate and Permanganate Class 12 Notes | EduRev 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 Manganate and Permanganate Class 12 Notes | EduRev K2MnO4  + MnO2  + O2

                                                    green Black

2K2MNO4 Manganate and Permanganate Class 12 Notes | EduRev 2K2MnO3 + O2

Silver and its compound

(I) 

Manganate and Permanganate Class 12 Notes | EduRev

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

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

Preparation : Already done.

Properties :

(i) 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)

(ii) Thermal decomposition:

(iii) Props. of AgNO3 : [Already done in basic radical]

6 AgNO3  +3I2  +3H2O → 5 AgI +AgIO3 + 6HNO3
(excess)

(iv) Ag2SO4 Manganate and Permanganate Class 12 Notes | EduRev 2Ag +SO2  +O2

(v) A(AgNO3Manganate and Permanganate Class 12 Notes | EduRev white ppt appears quickly

B(Na2S2O3Manganate and Permanganate Class 12 Notes | EduRev It takes time to give white ppt.

(vi) Ag2S2O3  +H2O Manganate and Permanganate Class 12 Notes | EduRev Ag2S +H2SO4

AgCl, AgBr, AgI (but not Ag2S) are soluble in Na2S2O3 forming

[Ag(S2O3)2]-3 complexes

(vii) AgBr +AgNO3  Manganate and Permanganate Class 12 Notes | EduRev  AgBr¯ +KNO3

                                                  (Pale yellow) ppt.

Heating effect :

2 AgNO3 Manganate and Permanganate Class 12 Notes | EduRev 2AgNO2 + O2

2 AgNO3 Manganate and Permanganate Class 12 Notes | EduRev 2Ag  2NO+ O2

(VIII)

Manganate and Permanganate Class 12 Notes | EduRev
Manganate and Permanganate Class 12 Notes | EduRev

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


ZinC Compounds

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

Preparation : 

1 ] 2Zn + O2 → 2ZnO

2 ] ZnCO3 Manganate and Permanganate Class 12 Notes | EduRev ZnO +CO2

3 ] 2Zn(NO3)Manganate and Permanganate Class 12 Notes | EduRev 2ZnO+ 4NO2  +O2

4 ] Zn(OH)2 Manganate and Permanganate Class 12 Notes | EduRev ZnO +H2O

Purest ZnO : 4ZnSO4  +4Na2CO3  +3H2O → ZnCO3.3Zn(OH)2¯ +  4Na2SO4  +3CO2
                                                                      Manganate and Permanganate Class 12 Notes | EduRev

Properties : 1 ) ZnO(cold) Manganate and Permanganate Class 12 Notes | EduRev 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

5) ZnO → Zn by H2 & C

ZnO+ H2 Manganate and Permanganate Class 12 Notes | EduRev Zn +H2O

ZnO+ C Manganate and Permanganate Class 12 Notes | EduRev Zn+ CO

6)It forms Rinmann's green with Co(NO3)2

2Co(NO3)2 → 2CoO +4NO2  +O2

CoO +ZnO → CoZnO2 or CoO - ZnO

Rinmann's green

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

ZnCl2

Preparation :

Manganate and Permanganate Class 12 Notes | EduRev

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

ZnCl2.2H2Manganate and Permanganate Class 12 Notes | EduRev Zn(OH)Cl +HCl +H2O

Zn(OH)Cl Manganate and Permanganate Class 12 Notes | EduRev ZnO +HCl

To get anh. ZnCl2 : Zn +Cl2 → ZnCl2

Zn +2HCl(dry) → ZnCl2  +H2

or Zn +HgCl2 → ZnCl2  +Hg

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

(ii) ZnCl2 + H2S → ZnS
                +NaOH → Zn(OH)2 Manganate and Permanganate Class 12 Notes | EduRev Na2[Zn(OH)4]
                +NH4OH → Zn(OH)2 Manganate and Permanganate Class 12 Notes | EduRev [Zn(NH3)4]

 

Uses : 1] Used for impregnating timber to prevent destruction by insects

2] As dehydrating agent when anhydrous

3] ZnO. ZnCl2 used in dental filling

ZnSO4 : -

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

Props. 1] ZnSO4 . 7H2Manganate and Permanganate Class 12 Notes | EduRev ZnSO4 . 6H2Manganate and Permanganate Class 12 Notes | EduRev

Uses : 1] in eye lotion

2] Lithophone making (ZnS BaSO4) as white pigment.

COPPER compounds

CuO :

Preparation : -

(i) CuCO3. Cu(OH)2 Manganate and Permanganate Class 12 Notes | EduRev 2CuO +H2O +CO2 (commercial process)

Malachite Green

(native Cu-carbonate)

(ii) 2Cu O2 → 2CuO & Cu2O +O2 → 2CuO

(iii) Cu(OH)2 Manganate and Permanganate Class 12 Notes | EduRev CuO +H2O

(iv) 2Cu(NO3)2 Manganate and Permanganate Class 12 Notes | EduRev 2CuO +4NO2  +O2

Properties :

(i) CuO is insoluble in water

(ii) Readily dissolves in dil. acids

CuO +H2SO4 → CuSO4  +H2O

HCl → CuCl2

HNO3 → Cu(NO3)2

(iii) It decomposes when, heated above 1100ºC

4CuO → 2Cu2O +O2

(iv) CuO is reduced to Cu by H2 or C under hot condition

CuO +C → Cu +CO­

CuO +H2 → Cu+ H2

CuCl2 :

Preparation : - CuO+ 2HCl (conc.) → CuCl2  +H2O

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

Preparation : -

(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 Manganate and Permanganate Class 12 Notes | EduRev [Cu(H2O)4] + [CuCl4]2- + 4H2O

(v) CuCl2 → CuCl by no. of reagents

(a) CuCl2  +Cu-turnings Manganate and Permanganate Class 12 Notes | EduRev 2CuCl

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

(c) 2CuCl2  +Zn/HCl → 2CuCl +ZnCl2

(d) CuCl2 + SnCl2 → CuCl +SnCl4

Manganate and Permanganate Class 12 Notes | EduRev

CuI2 does not exist.

 CuCl2.2H2O Manganate and Permanganate Class 12 Notes | EduRev CuCl2  + 2H2O

CuSO4 :

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}

 

Preparation : -

(i) It is crystallised as CuSO4.5H2O

(ii)  Manganate and Permanganate Class 12 Notes | EduRev
Manganate and Permanganate Class 12 Notes | EduRev

(iii) Revision with all others reagent

Iron compounds

FeSO4.7H2O

Preparation : -

(i) Scrap Fe + H2SO4 → FeSO4  + H2­

     (dil.)

(ii) From Kipp's waste

FeS + H2SO4 (dil.) → FeSO4  + H2

(iii) FeS2 + 2H2O + Manganate and Permanganate Class 12 Notes | EduRevO2 → FeSO4 + H2SO4


Properties : -

(i) It undergoes aerial oxidation forming basic ferric sulphate

4FeSO4  + H2O + O2 → 4Fe(OH)SO4

(ii) FeSO4.7H2Manganate and Permanganate Class 12 Notes | EduRev FeSO4 Manganate and Permanganate Class 12 Notes | EduRev Fe2O3  +SO2  +SO3

     anh.white

(iii) Aq. solution is acidic due to hydrolysis

FeSO4  + 2H2Manganate and Permanganate Class 12 Notes | EduRev 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

FeO(Black) :

PrepnFeC2O4 Manganate and Permanganate Class 12 Notes | EduRev FeO +CO +CO2

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

Fe3O4 and iron.

4FeO → Fe3O4  +Fe

FeCl2 :

Preparation : - Fe+ 2HCl Manganate and Permanganate Class 12 Notes | EduRev FeCl2  +H2

OR

2FeCl3 + H2 Manganate and Permanganate Class 12 Notes | EduRev 2 FeCl2  +2HCl


Properties: -

(i) It is deliquescent in air like FeCl3

(ii) It is soluble in water, alcohol and ether also because it is sufficiently covalent in nature.

(iii) It volatilises at about 1000ºC and vapour density indicates the presence of Fe2Cl4. Above 1300ºC density becomes normal

(iv) It oxidises on heating in air

12FeCl2 + 3O2 → 2Fe2O3  +8FeCl3

(v) Hevolves on heating in steam

3FeCl2  +4H2O → Fe3O4  +6HCl +H2

(vi) It can exist as different hydrated form

FeCl2.2H2O → Colourless

FeCl2.4H2O → pale green

FeCl2.6H2O → green

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