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Showing posts with label TRANSITION ELEMENTS:. Show all posts
Showing posts with label TRANSITION ELEMENTS:. Show all posts

Sunday, May 8, 2022

Nature of Transition Metals Oxides:

The oxides of  transition metals will be acidic , basic or amphoteric  as camparative with its oxidation state. The follow following trends.

Trends (1): The higher oxidation state of the central metal atom , the more covalent character  and oxide will be more acidic in nature.

Trends (2): The Lower oxidation state of the central metal atom , the more ionic character and oxide will be more basic in nature.

Trends (3): The moderate oxidation of central metal atom oxide will be amphoteric in Nature .


       Oxidation State

Nature of Oxides

              +1 , +2 , +3

Basic ,Except Cr2O3

                        +4

Amphoteric e.g. MnO2

                +5, +6, +7

Acidic,V2O5,CrO3,MoO3,Mn2O7,OsO4


Example of oxides of (Mn):

Oxides

Oxidation state

Nature

MnO

+2

Basic

MnO2

+4

Amphoteric

Mn2O7

+7

Acidic


Example of oxides of (Cr):

Oxides

Oxidation state

Nature

CrO

+2

Basic

Cr2O3

+3

Amphoteric

CrO3

+6

Acidic



Related Questions:


Oxides:

Monday, April 25, 2022

What is the structure and structural characteristic of dichromate kon (Cr2O7)-2?

The whole molecule dichromate ion (Cr2O7)-2 is non planer and polar and oxygen atom of (Cr-O-Cr) oxy-linkage does not involve in delocalization due to maximum repulsion hence two Cr-O bond have equal length and bond order may be/equal to one while other six Cr=O bond have eqaual bond length.


In dichlorine heptaoxide (Cr2O7)-2 , two (CrO4 )-2 group connected with an oxygen atom which is sp3 hybridised (non planer) and bond angle may be expected 109⦁28’ but actually due to the presence of two lone pair on oxygen atom the Cr-O-Cr bond angle deviated from ideal and it may be greater (119⦁) than ideal bond angle.

What is the structure and structural characteristic of dichlorine heptaoxide (Cl2O7)-2?

Related Questions:

Tuesday, February 4, 2020

Why transition metals and their compounds are act as catalyst?

Transition metals and their compounds are known to act as good catalyst due to the following reasons: 
(1) Due to the variable oxidation state, they form unstable intermediate compounds and provide a new path with lower activation energy for the reaction (Intermediate compound formation theory) and hence rate of reaction is increases.
(2) In some cases the finely divided metals or their compounds provide a large surface area for adsorption and the adsorbed reactants react faster due to the closer contact (Adsorption theory).
Some Important Catalytic:
1. TiCl3 + Al(C2H5)3 Used as Ziegler – Natta catalyst 
2. V2O5 Converts SO2 to SO3 in the contact process for making H2SO4
3. MnO2 Used as a catalyst to decompose KClO3 to give O2
4. Fe Used in Haber – Bosch process for making NH3
5. FeCl3 Production of CCl4 from CS2 and Cl2
6. FeSO4 & H2O2 Fenton's reagent 
7. PdCl2 Wacker process for the following conversion 
            C2H2 + H2O + PdCl2 to CH3CHO + 2HCl + Pd 
8. Pd For hydrogenation (Phenol to Cyclohexanol) 
9. Pt/PtO Adam catalyst used for reduction 
10. Pt SO2 to SO3 contact process 
11. Pt Cleaning car exhaust fumes 
12. Cu In manufacture of (CH3)2SiCl2
13. Cu/V Oxidation of cyclohexanol 
14. CuCl2 Deacon process or making Cl2 from HCl 
15. Ni Raney nickel
16. Pt/Rh Ostwald's process. NH3 to NO
17. Baeyer's reagent - 1% alkaline solution of KMnO4.
18. Etard's reagent- CrO2Cl2 Chromyl chloride.
19. Luca's reagent- Anhydrous ZnCl2+ concentrated HCl.
20. Barford reagent- Cu(CH3COOH)2+ CH3COOH.
21. Brown catalyst- Nickel Boride.
22. Lindlar's Catalyst- Pd/C use to convert alkynes to cis alkenes.
23. Adkin's catalyst- (CuO.CuCr2O4) or CuO.Cuo.Cr2O3, Copper chromite is use to reduce corboxylic acids into corresponding alcohols 

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