Welcome to Chem Zipper.com......: 2020

Search This Blog

Wednesday, December 30, 2020

What is Hypovalent species or compounds ?

The compounds or ions which doesn't follow octet rule inspite of that contains less than eight electrons and also stable called Hypovalent species.

For examples BeF2,BF3, CH4+, NF2+, B2H6, Be2Cl4 etc

Hypovalent species may act as Lewis acid always.


What is Hypervalent species or compounds?

The compounds or ions which doesn't follow octet rule inspire of that contains more than eight electrons and also stable called Hypervalent species.

For examples XeFe2(10e), XeFe4(12e), SF4(10e), SFe6(12e), IFe7(14e), I2Cl6(10e), TeF5(12e) etc

Hypervalent species may act as Lewis acid but not always.


Tuesday, December 29, 2020

Cage like Structure

P4, P4O4, P4O10, P4S3, P4S10, N4(CH2)6

Structure of P4O6 and P4O10

Normal Oxides:

The Oxides in which oxidation state of central atom is found to be one of the it's common oxidation state. The are also called acid anhydrides because on dissolving them  into water oxygen acid is formed in which oxidation state of central atom is found to be same as present in Oxide.

Examples:  B2O3, CO2, N2O3, N2O5, SO2, SO3, Cl2O7, XeO3, XeO4 etc.


Peroxides

The oxides in which  calculated oxidation state of central atom is more than maximum oxidation state of central atom due to the presence of peroxide linkage.

For examples, H2O2, Na2O2, BaO2, PbO2, CrO5 etc.

Suboxides:

The oxides contains more oxygen atoms as compare to central atoms and according to valency requirements of central atoms number of oxygen atoms are not sufficient.

For examples B2O3, C3O2, C12O9, Pb3O, Rb9O2, Cs11O3 etc. 


Mixed Oxides:

The oxides in which oxidation state of oxygen atom is found to be it's uncommon oxidation state on central atom. Mixed oxides on dissolving in water undergo "disproportionation" 

For examples B2O3, ClO2, Cl2O7 , N2O5 , As2Oetc.

Related Questions:

Which oxides (Anhydrides) gives two Oxyacids in water ?

What are the structural difference between oxides ( P4O6 and P4O10) of phosphorous?

What are common structural features of oxides (P4O6 and P4O5) of phosphorous?

Why Nitrogen dioxide (NO2) dimerises to form Dinitrogen tetraoxide (N2O4)?

Why Nitrogen dioxide (NO2) is coloured but Dinitrogen tetraoxide (N2O4) is colourless?

What is product obtained when N2O5 is treated with NaCl?

What are Nature of the alkali metal oxides(O-2), peroxides (O2-2) and superoxides (O-1/2) in hydrolysis reactions?

What are the SESQUI OXIDES ? give the examples.

Which is more basic oxide ion (O-2 ) or hydroxide ion( OH- ) and why ?

Perovskite Oxides:

ABO3 type Oxides are also called Perovskite for examples CaTiO3  And BaTiO3.


Sesqui Oxides

The oxides in which number of oxygen atoms pet central atoms is found to be 3/2 .And it may be ionic, covalent or missed oxides.Mostly M2O3 type Oxides (Corundum structure) are sesqui Oxides.  Where M+2= Al, Ga, Ti, V, Cr, Fe, The etc.

Examples , B2O3, N2O3, Al2O3 ( covalent oxide) Fe2O3 (ionic oxide) Pb2O3 (mixed oxide)

Super Oxides

The oxides in which oxidati state of oxygen atom always -1/2, and super oxides are always ionic and paramagnetic.

For examples KO2 , PbO2, (NH4)O2 etc.

KO2 => k+[O-O]-. Have following character

Bond pair -2

Lone pair -2

Hybri- sp2, linear non planner and bond angle not applicable.



Neutral Oxides

The are  oxides of non metals which are neither acidic nor basic in nature or these are not  react  with acids or bases for examples.

                                 CO, NO, N2O, H2O and OF2 etc.


The Usanovich Acid- Base Concept

 According to this concept  acids are any chemical species which react with bases and gives cations or accept anions or electrons.

Similarly Bases are a chemical species which react with acids and gives anions or electrons or cations

Hard and Soft  acids and bases:


Lux- Flood Acid-Base Concept:

The Lux-Flood concept is given by Lux in 1929 and supported by Flood in 1947. Lux-Flood concept is based on oxide ion acceptor and donor tendency.

Lux-Flood bases:  According to this concept bases are those species which can donate oxide ions examples.

Lux-Flood Acids:  According to this concept Acids are those species which can accept oxide ions.

Chemical Reactions according Lewis acid-base concept:

Acid-base reaction in term Lux-Flood acid and base is a specific reactions in which oxide ions are mainly use in molten form or at high temperature.

Amphoteric Nature of Oxides as per Lux-Flood Concept:

Acidic Nature of Xenon fluoride as per Lux-Flood Concept:

According to Lux –Flood concept Xenon fluorides accept oxide ions from other compounds and insert fluorides ions in its place.

For examples

The Order of decreasing Lux-Flood acidity of Xenon Fluorides is given as:

Limitations of Lux-Flood Acid –base Concept:

(1) It is dealing with anhydrous reaction in fused molten oxides and  other high temperature reactions found in metallurgy and ceramics.

(2) When Lux-Flood, acidic and basic of oxide react with water gives corresponding acid and base.

Limitations of Lux-Flood Acid –base Concept:

(1) Base must contain oxide ion and acid must have accept oxide ions.

(2)It fails to explain reaction without  metal ions

The Solvent system(Self or Auto Ionization of Solvents)

The most common concept of acids and bases is due to Cady and Elsey. Most of the solvents undergo auto-ionization and form cation and anions like water, regardless it contains protons or not for examples; H2O, NH3, H2SO4, HNO3, POCl3, BrF3, N2O4, NOCl, CH3COOH,


  1. Solvolysis in liquid N2O4:
  2. Hydrolysis reactions:
  3. Solvolysis in liquid NH3 (Ammonolysis):
  4. Auto ionization of anhydrous Sulphuric acid:
  5. Solvolysis in Liquid SO3:
  6. Solvolysis in Liquid HF:

 Related Questions: 

Why aqueous solution of AlCl3 is acidic in nature ?

What happen when aq AlCl3 react with Acid or Base?

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

Why BF3 do not exist as dimer?. Explain.

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

B-F bond length in BF3 is shorter than B-F bond length in (BF4)- why?

When B2H6 is allowed to react with following Lewis bases, then how may given Lewis base form adduct through symmetrical Cleavage of B2H6.

What is product of reaction between diborane (B2H6) and ammmonia (NH3)?

Why methylation of Diborane (B2H6) replace four hydrogen only ?

What is Use of Boric Acid?

What is use of Orthoboric acids?

What is basicity of "Boric acid" ?

Why Boric acid exist in solid state ?

What is structure of solid Ortho Boric acid ?

What is effect of heat on Borax?

What is the structure of trimetaboric acid and trimetaborate ion?

What is the Sodium per borate ,give the structure and its uses?

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

What is the molecular formula of Borax ?

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

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

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

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


Monday, December 28, 2020

Why Bond length of O-O is greater in H2O2 than O2F2?

Electronegativity of F is much more than hydrogen and also hybridization of oxygen atoms in of H2O2 and O2F2 both have (sp3) same . According bent’s rule those hybrid orbitals containing flourine atom have less % s-characterand more p-character while other orbitals have more % s-character and less % s-character hence O-O bond length in O2F2 is shorter thane H2O2.

Related Questions:

What is Bent’s rule of hybridization?

Which of the following compound have longest (S=O)bond length , O=SF2, O=SCl2, O=SBr2.





What is Bent’s rule of hybridization?

According to the bent's rule the more electronegative atom not only prefer to stay in that Hybride orbital which having less  % S character (more p-character) but it also decreases % S-character and increases % P-character in its attached orbital from the central atom.


On increasing % s character in hybrid orbital , the bond length  decreases while bond angle increases.

For example:C-H bond of CH4 is longer than C-H bond of floromethan (CH3F) because In CH4 all the Sp3 hybrid orbitals are equal in term of  s-% character(25%) and % p-charater(75%)  so that all C-H bond in CH4  are equal while in case of CH3F the hybrid orbital has more p-character (more than 75%) and less s-character (less then 25%) containg fluorine atom and other hybrid orbitals have less p-character (less than75%) and more s-character (more than 25%) hence C-H bond length of CH3F decreases.

EXCEPTIONS OF BENT’S RULE:

 (1): Bent’s rule is applicable in those molecules where central atoms are same and they are also in same Hybridization.

For example N-N bond length cannot be compared in N2H4 and N2O4 using Bent rule.

(2): Bent’s rule violets in those molecules where steric factor’s plays dominating rule.

Related Questions:

What is Bent’s rule of hybridization?

Which of the following compound have longest (S=O)bond length , O=SF2, O=SCl2, O=SBr2.

How to arrange increasing (C-H) bond length in increasing order and H-C-F bond angle in the given compounds, CH4, CH3F, CH2F2 and CHF3 ?

According to the bent's rule the more electronegative atom not only prefer to stay in that Hybride orbital which having less  % S character (more p-character) but it also decreases % S-character and increases % P-character in its attached orbital from the central atom depending on circumstance.



Sunday, December 27, 2020

When B2H6 is allowed to react with following Lewis bases, then how may given Lewis base form adduct through symmetrical Cleavage of B2H6.

NH3, CH3NH2, Pyridine , CO, T.H.F., PH3, PF3, (Me)3N, (Me)2NH.

SOLUTION:

B2H6 undergoes symmetrical cleavage with large size weak Lewis base like PH3, PF3, Pyridine , THF , (Me)3N , CO.

Related questions:

(1) Why Ga has small size than Al exceptionally

(2) Why aqueous solution of borax reacts with two moles of acids ?

(3) What is structure of solid Ortho Boric acid ?

(4)What is the structure of trimetaboric acid and trimetaborate ion?  

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

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

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

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

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

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

(11) Three-center two-electron bond (3C-2e Bond):Structure of AlCl3:

(12) What is the molecular formula of Borax ?

(13) What is the difference between the structure of AlCl3 and diborane?

Give the examples of covalent species which have different hybridization in gaseous state as well as in liquid phase?

 


What happen when aq AlCl3 react with Acid or Base?

When a soluble aluminium salt is placed in water at room temperature. Initially the aluminium ion is surrounded by six water molecules and the complex ion has the predicted octahedral Geometry.

This complex ion behaves as an acid in water, losing protons, and a series of equilibria are established (H+ is used, rather than H3O+for simplicity):

These equilibria give rise to an acidic solution in water, to the Hexahydroxoaluminate(iii) ion [Al(OH)6]3- in a strongly alkaline solution, and only in strongly acidic solutions is the hexaaquo ion [Al(H2O)6]3+ found. 

The solid hydrate, often written AlCl3. 6H2O and more correctly [Al(H2O)6]Cl3 can, therefore, only be obtained from a strongly acidic solution. The reaction with water resulting in the liberation of a proton is again known as hydrolysis and occurs whenever the central metal ion is small and highly charged (i.e. having a high surface density of charge), for example in salts of iron(III), chrornium(III).

Related Questions: 

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

(2) Why Ga has small size than Al exceptionally

(3) Why aqueous solution of borax reacts with two moles of acids ?

(4) What is structure of solid Ortho Boric acid ?

(5) What is the structure of trimetaboric acid and trimetaborate ion?  

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

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

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

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

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

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

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

(13) What is the molecular formula of Borax ?

(14) What is the difference between the structure of AlCl3 and diborane?

What is the structure of Melamine and how can synthesied ?

 Melamine formed by trimerization of  H2N– CN ( cyanamide ). Which is also known as  cyanuric amide.



Why SF6 is inert while SF4 is a very reactive molecule that reacts with H2O rapidly and vigorously?

 

The fact that SF6 does not react with water is not due to thermodynamic stability. Rather, it is because there is no low-energy pathway for the reaction to take place (kinetic stability). Six fluorine atoms surrounding the sulfur atom effectively prevent attack of water molecules and the sulfur atom has no unshared pairs of electrons where other molecules might attack. In SF4 , not only is there sufficient space for an attacking species (water) to gain access to the sulfur atom, but also the unshared pair is a reactive site. As a result of these structural differences, SF6 is relatively inert, whereas SF4 is very reactive.


Related Questions:






Why is BCl3 a strongerLewis acid than BF3 ?

The strength of a Lewis acid is a measure of its ability to attract a pair of electrons on a molecule that is behaving as a Lewis base. Fluorine is more electronegative than chlorine, so it appears that three fluorine atoms should withdraw electron density from the boron atom, leaving it more positive.This would also happen to some extent when the peripheral atoms are chlorine, but chlorine is less electronegative than fluorine. On this basis, we would expect BF3 to be a stronger Lewis acid. However,in the BF3 molecule, the boron atom uses sp2 hybrid orbitals, which leaves one empty 2p orbital that is perpendicular to the plane of the molecule. The fluorine atoms have filled 2p orbitals that can overlap with the empty 2p orbital on the boron atom to give some double bond character (Back Bond) to the B–F bonds.

 


As a result of the contribution by resonance structures having some double bond character, the boron atom in BF3 is not as electron deficient as it is in BCl3. And hence BCl3 a stronger Lewis acid than BF3

What are the characteristics features of π-bond ?

(1) π-bond fired by lateral (sidewise) overlapping of atomic orbitals.

(2) lateral overlapping is only partial, so bonds formed are weaker and hence more reactive than sigma bond.

(3) Free rotation about a π- bond is not possible.

(4) π- bond is weaker than sigma bond.

(5) π-bonds are non directional, so do not determine the shape of a molecules.

(5) π- bond take part in resonance.

(6) π- bond formed by pure or anhybrid orbitals.


What is the difference between 2p and 3p orbitals?

Importance difference in between 2p and 3p Orbitals is their energy.

The energy of atomic orbitals depends upon principal as well as azimuthal quantum number, which is  more common known as (n+l) rule .
According to (n+l) rule the atomic orbital has less (n+l)  value also has less energy vice versa.
If the value of (l):is same for two different orbitals then the greater the value of n greater is energy and vice versa.
For 2p => n= 2, l=0,. =>n+l= 2+0=2
For 3p => n= 3, l=0,. =>n+l= 2+0=3
Hence 3p have more energy than 2p orbital

Why are 2p orbitals higher in energy than 2s?

The energy of atomic orbitals depends upon principal as well as azimuthal quantum number, which is  more common known as (n+l) rule .
According to (n+l) rule the atomic orbital has less (n+l)  value also has less energy vice versa.
For 2S => n= 2, l=0,. =>n+l= 2+0=2
For 2p => n= 2, l=2,. =>n+l= 2+1=3
Hence 2p have more energy than 2s orbital

Does 2s and 2p have the same energy?

'NO' the energy of atomic orbitals depends upon principal as well as azimuthal quantum number, which is  more common known as (n+l) rule .
According to (n+l) rule the atomic orbital has less (n+l)  value also has less energy vice versa.
For 2S => n= 2, l=0,. =>n+l= 2+0=2
For 2p => n= 2, l=2,. =>n+l= 2+1=3
Hence 2p have more energy than 2s orbital

Saturday, December 26, 2020

Which orbital has much overlap capacity?

When internuclear distance is fixed then overlapping extent of atomic orbitals depends on directional nature of orbitals. And higher the directional nature of orbitals more stronger will be extent of overlapping and more stronger bond will form
Order of extent of over lapping given as:
          2p-2p > 2s-2p > 2s-2s

Why the extent of overlap is more in 2p-3d than 2p-3p?

The order of overlapping strength of orbitals is given as:

2pπ-2pπ>2pπ-3dπ>2pπ-3pπ>3pπ-3pπ.
The strength of π-bond is directly proportional to the overlapping strength of orbitals because on greater overlapping distance between two nuclei decreases and bond strength increase hence order of π-bond also given as:

2pπ-2pπ>2pπ-3dπ>2pπ-3pπ>3pπ-3pπ.

2pπ-2pπ, π-bonding is stronger than 2pπ-3dπ, π-bonding due to the lower energy gap (n=2) between them.
The importance comparison is in between 2pπ-3dπ and 2pπ-3pπ. The overlapping strength of 2pπ-3dπ  is more than 2pπ-3pπ this is due to fact that , the 3d orbitals have two lobes which are more bent than 3p orbitals. That why overlapping strength increase.

Friday, December 25, 2020

How to determine order of bond angle of Me-O-Me, H3Si-O-SiH3 and (ph)3Si-O-Si(Ph) ?

 (1) Oxygen of Me-O-Me is sp3 hybridised so C-O-C bond angle is more than 109’28” approx 110” due to crowding of methyl group.

(2) In disilyl ether , oxygen is Sp2 hybridised and planer due to back bonding between oxygen and silicon atom.  In this back bonding lone pair of oxygen atom donate to the vacant d orbital of silicon atom  due to this fact bond lengths of Si-O is decrease and  increases (approx 140”).

(3) In (Ph)3Si-O-Si(Ph)3  compounds Si-O-Si bond angle is Approx 180 due to back bonding and hybridisation is Sp.


Related Questions:

Why trimethylamine amine ( N(CH3)3) is tetrahedral while trisilyl amine (N(SiH3)3) planner.?









How to compared bond angle (C-N-C) and (Si-N-Si) in trimethyl amine and trisilyl amine respectively?

Nitrogen (N) atom in trimethyl amine [N(CH3)3] is sp3 hybridised and tetrahedral ( bond angle ~107)  due to non bonding electron pair of N is localised (more basic). On the other hand N atom of trisilyl amine [N(SiH3)3] is sp2 hybridised and trigonal planner (bond angle~120).This is due to the participation of non-bondlng pair of N into pπ-dπ back banding. Due to this delocalization of non-bonding electron pair of N in trisilyl amine it is also less basic

Related Questions:

Why trimethylamine amine ( N(CH3)3) is tetrahedral while trisilyl amine (N(SiH3)3) planner.?









What is structure (CF3)2-Al-O-Al-(CF3)2 and also find the number of pi bond or Back bond?