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Sunday, June 14, 2020

Why Ga has small size than Al exceptionally ?

When we move down to Ga from Al we see that 3d shell fills before Ga and due to increase in effective nuclear change size of Ga in smaller than aluminium.
 

Related Questions:

Why Ga has small size than Al exceptionally

Why aqueous solution of borax reacts with two moles of acids ?

What is structure of solid Ortho Boric acid ?

What is the structure of trimetaboric acid and trimetaborate ion?  

Why Borazine is more reactive than benzene towards Electrophic Aromatic substitution reactions ?

Why Borazine (B3N3H6) is also known as inorganic benzene ?.

Why B-F bond length in BF3 is shorter (130 pm) than B-F bond Iength in BF4- (143 pm)?. Explain.

Why B-F do not exist as dimer?. Explain.

Although anhydrous aluminium chloride is covalent but its aqueous solution is ionic in nature. Why?

Why Boric acid become strong acid in the presence of cis 1,2-diol or 1,3-diol ?

Four-center two-electron bond (4C-2e Bond): Structure of AlCl3:

What is the molecular formula of Borax ?

What is the difference between the structure of AlCl3 and diborane?

Titration of Borax: Tincal : Suhaga :

Structure of Borax: Tincal or Suhaga:

Titration of Boric Acid:

DIBORANE-HYDRIDE OF BORONE-(B2H6):

CHEMICAL PROPERTIES OF DIBORANE:

STRUCTURE OF BORON NITRIDE:

STRUCTURE OF BORAZINE OR BORAZOLE:

STRUCTURE OF DIBORANE :

BORIC ACID (H3BO3) :

BORAX BEAD TEST:

What are the Pseudohalogens or halogenoids?

We know that dimers of halide ions are called halogens, In the similar way covalent dimers of the pseudohalide ions are called pseudohalogens or halogenoids. 
The pseudohalogens known are :
Cyanogen (CN)2
Oxycyanogen (OCN)2
Thiocyanogen (SCN)2
Selenocyanogen (SeCN)2
Tellurocyanogen (TeCN)2
Azido carbon disulphide (SCSN3)2

What are Pseudohalides ? and What is similarity with halides?

The ions consisting of two or more electronegative atoms of which at least one is nitrogen, that have properties similar to those of halide ions. These ions are called pseudohalide ionsPseudohalide ions are univalent and these form salts resembling halide salts. The pseudohalide ions are :
Cyanide ions (CN-)  
Isocyanide ion (NC-)
Cyanate ion (OCN-
Fulminate ion (ONC-)
Thiocyanate ions(SCN-)
Isothiocyanate ion (NCS-)
Selenocyanate ion (SeCN-)
Tellurocyanate ion (TeCN-)
Azide ion (N3-) : 
Azido carbon disulphide ion (SCSN-3)

The best known pseudohalide is CN-.This resembles Cl- , Br- and I- in the following respects:
(i) It forms an acid, HCN. 
(ii) It can be oxidised to (CN)2 molecule. 
(iii) It forms insoluble salts with Ag+, Pb2+ and Hg22+
(iv) It forms large number of complexes similar to halide complexes, e.g. [Cu (CN)4]2- and [CuCl4]2, [Co(CN)6]3- and [CoCl6]3- 
(v) Inter-pseudohalogen compounds ClCN, BrCN and ICN can be formed. 
(vi) AgCN is insoluble in water but soluble in ammonia likeAgCl.

Related Questions:

Why halogens are insoluble in water ?
Is F2 bond is stronger than Br2 ?
Which is best known pseudohalide ?
Iodine forms I3- but F2 does not form F3- ions. Why?
Number of lone pair present at central atom of I3- ion and also give hybridisation and shape of ion?
How many maximum atoms of IF7 are present in the same plane ?
What are the Pseudohalogens or halogenoids?
What are Pseudohalides ? and What is similarity with halides?
Although electron affinity of chlorine is higher than fluorine, yet fluorine act as better oxidizing agent than chlorine? Explain.
Although electron affinity of chlorine is higher than fluorine, yet fluorine act as better oxidizing agent than chlorine? Explain.
Why chlorine trifluoride (ClF3) exists but fluorine trichloride (FCl3) does not?
Why Chlorine (Cl2) bleaches a substance permanently but sulphuredioxide (SO2) does it temporarily?
What is the correct order of electronegativity of Cl atoms in HClO, HClO2, HClO3 and HClO4 ?
How does the thermal stability of oxy acids of chlorine increase with an increase in the oxidation state of chlorine atom ?
Which of the following is a strongest acid among oxy acids of chlorine and why? "HClO, HClO2, HClO3, HClO4"
Which will have very fast tendency to dimerized ClO2 or NO and why?
Which of the following is a strongest acid among oxy acids of chlorine and why? "HClO, HClO2, HClO3, HClO4"

What is Steric Inhibition of Deprotonation effect ? Or SID effect ?

We know that picric acid is weak acid than expected this is fact that when picric acid releases a proton it becomes an anion for which repulsion results between oxygen atoms of phenoxide ion and oxygen of nitrate group, commonly known as Steric Inhibition of Deprotonation (SID effect). This also results in slight unstability of phenoxide ion and also decrease acidity. Thus picric acid is a weak acid than expected ever.

Related Questions:

  1. Highly branched carboxylic acids are less acidic than unbranched acids. Explain why?
  2. Benzamide is less easily hydrolysed than methyl benzoate. Why ?
  3. Alcohols and Phenols both are acidic but phenols are more acidic. Why?
  4. Which is more acidic 2-methyl benzoic acid , 3-methyl benzoic acid or 4-methyl benzoic acid.?
  5. Why is o-toluic acid (2-methyl benzoic acid) stronger than benzoic acid ?
  6. What is the ortho effect? Why are nearly all ortho substitute benzoic acids (except some groups) stronger acid than benzoic acid?
  7. Name of groups which does not show ortho effect in benzoic acid?
  8. Why Picric acid (2,4,6-trinitrophenol) is weak acid then expected ?
  9. What is Steric Inhibition of Deprotonation effect ? Or SID effect ?
  10. Alcohols and Phenols both are acidic but phenols are more acidic. Why?
  11. Among orthochlorophenol and orthofluorophenol, which will be a stronger acid and why?
  12. Why The phenoxide ion is more stable than phenol ?
  13. What is correct acidic strengths order of the haloforms acids ? Give correct explanation.
  14. Lower aliphatic acids having 1 to 5 carbons are soluble in water but higher fatty acids having six or more than six carbon are insoluble in water but soluble in alcohol. Explain.
  15. Phenoxide ion is more stable than an alkaoxide. why?
  16. Why does aqueous sodium bicarbonate solution dissolve carboxylic acids but not phenol though they are also acidic ?
  17. Chloroform is more acidic than fluoroform why?
  18. Fluorine is more electronegative than chlorine even then, p-flurobenzoic acid is weaker acid than p-chlorobenzoic acid explain ?

Why Picric acid (2,4,6-trinitrophenol) is weak acid then expected ?

Picric acid is weak acid than expected due to the presence of three Nitro groups (show strong -I as well as -M effect); this is fact that  6-membered cyclic H-bonding takes place between H of -OH and O atoms of -NO2 groups which lower acidity significantly than the expected acidity.

And second fact that when picric acid releases a proton it becomes an anion for which repulsion results between oxygen atoms of phenoxide ion and oxygen of nitrate group, commonly known as Steric Inhibition of Deprotonation (SID effect). This also results in slight unstability of phenoxide ion and also decrease acidity. Thus picric acid is a weak acid than expected ever.