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Showing posts with label INORGANIC MECHANISM:. Show all posts
Showing posts with label INORGANIC MECHANISM:. Show all posts

Wednesday, January 10, 2024

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 and hence we can apply bent’s rule.

According bent’s rule more eletronegative atoms reduce % s-character (or increases % p-character vice versa) of those hybride orbital in which they attach. So in case of O2F% s-character of those hybride orbital decrease which have  flourine while % p-character increases in same way % s-character of  remaing hybride orbital inceases and p-character decreases hence its bond length also (bond length is directly proportional to % p-character) decreases.  hence O-O bond length in O2F2 is shorter thane H2O2.

Thursday, January 28, 2021

Hydrolysis reactions (Inorganic reactions):

Hydrolysis is  a chemical process in which  a certain molecule is split into two parts by the addition of a molecule of water. One fragment of the parent molecule gains a hydrogen ion (H+) from the addition of water. The other group collects the remaining hydroxyl group(OH-) for examples :

(1) During  hydrolysis of a covalent compound having non metal central atom, if water molecule attack at central atom and hydrolysis occurs at room temperature then oxy acid of the non metal will be formed, if the central atom is in it one of the common oxidation state.  Oxidation state of  central atom of the oxy acid  will be same as its in the given substrate, However this rule is not applicable to XeF2, XeF4 and XeF3.

(2) hydrolysis reactions occur in non redox reaction except XeF2 and XeF4 and  mixed anhydride i.e. central atoms has its uncommon oxidation state for examples;

(3) During  hydrolysis, hybridization of central atom in transition state and may  or may not change.

(4) BF3, SiF4, CCl4, SbCl3, and BiCl3 undergo partial hydrolysis even in excess of water while PCl5, SF4, SeF6,IF7, XeF6 H4P2O8, H2S2O8,P4O10 can undergo partial as well as complete hydrolysis by adjusting the amount water.

(5) Rate of hydrolysis is directly proportional to the positive (+) charge density at least electronegative atoms of  substrate provided. And  the least electronegative  atom must contain vacant  orbital and have no crowding.The order of  rate of hydrolysis of some compounds are given as;

PCl5(V) > SiCl4(IV) > AlCl3(III) > MgCl2(II) > CCl4 (NO vacant orbital) > SF6 (Crowding)

Related Questions:

Question (1): Why aqueous solution of AlCl3 is acidic in nature?

Question (2): What happen when aq AlCl3 react with Acid or Base?

Question (3): Although anhydrous aluminium chloride is covalent but its aqueous solution is ionic in nature. Why?

Question (4): Arrange in increasing order of extent of hydrolysis [ CCI4, MgCI2, AICI3, PCl5, SiCI4].

Question (5): Although Sulphur contain vacant d-orbital but SF6 does not undergo hydrolysis. Why?

Question (6): CCl4 can not be hydrolysed but SiCl4 can be. Why?

Question (7): What are the hydrolysis products of urea?

Question (8): Why SF6 is inert where as SF4 is highly reactive towards H20?.

Question (9): Why SF6 behaves inert towards hydrolysis?

Question (10): Why PCl3 hydrolysed while NCl3 can not be hydrolysed?

Question (11): Why hydrolysis of NCl3 gives NH4OH and HOCl, while PCl3 on hydrolysis gives H3PO3 and HCl?

Question (12) NCl3 and PCl3 on hydrolysis give different kinds of products. These is because of


Sunday, January 17, 2021

What is the structure of (O2F2) oxygen fluoride

The compound id produced as result of glow dischage through amixture of O2 and F2 at -180 to -190 degree (c). As should be expected. O2F2 is an extremely reactive fluorinating agent. Under the conditions that produce OF2, small and O4F2 are produced, but these unstable compounds decomposed at liquid nitrogen temperatures.

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 and hence we can apply bent’s rule.

According bent’s rule more eletronegative atoms reduce % s-character (or increases % p-character vice versa) of those hybride orbital in which they attach. So in case of O2F2 % s-character of those hybride orbital decrease which have  flourine while % p-character increases in same way % s-character of  remaing hybride orbital inceases and p-character decreases hence its bond length also (bond length is directly proportional to % p-character) decreases.  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.

Friday, January 15, 2021

Oxy acids of Chlorine:

Chlorine, bromine and Iodine form oxy acids easly due to less electronegative than oxygen but oxy acids of fluorine are unsatble due to high electronegativity only hypofluorous (HOF) acid is stable.

O.S of halogens

Name of acids

Name of  salts

fluorine

Chlorine

Bromine

Iodine

(+1)

Hypohalous

Hypohalite

HOF

HOCl

HOBr

HOI

(+2)

Halous

Halite

----

HClO2

----

----

(+3)

Halic

Halate

----

HClO3

HBrO3

HIO3

(+4)

Perhalic

Perhalate

----

HClO4

HBrO4

HIO4


Important Note:
All the hypohalous acids (HXO) are unstable and readly form HXO3. Among the relative order of stability is: HClO > HBrO > HIO

Relative acidic strength of oxy acid Halogens:

(1) According to Bronsted Lowery concept, a strong acid has weak conjugate base and vice versa. 

The given oxy acids of chlorine HCIO, HCIO2, HClO3 and HClO4 and their conjugate bases are CIO-, CIO2-, ClO3-, ClO4- respectively. These anions are stabilised to greater extent, due to the presence of π-bond and lone pair, if number of π-bond increase extent of stabilisation increase. In case of ClO- there is no π-bond hence if form less stable conjugate base hence act as weak acid while in case of ClO4- it has three pπ-dπ bond which stablised greater extent and form more stable conjugate base hence it conjugate acid (HClO4) is strongest acid. Oxy acids of chlorine and their number of pπ-dπ bonds given as:

HOCI (0=Pπ-dπ bond)

HOCIO (1=Pπ-dπ bond)

HOClO2 (2=Pπ-dπ bond)

HOCIO3 (3=Pπ-dπ bond)

Thus overall order of acidic strength of oxy acids of chlorine is as:

Acidic srength of acid as :  (HClO) < (HClO2)<(HClO3)<(HClO4

(2) In general the relative strength of oxy acid can pridicted on the basis of electronegativity and oxidation state of central non metal atom.

(1) For given oxy acid on increasing of electronegativity acidic strength increses for example perchloric (HClO4) is stronger acid than perbromic acid(HBrO4), which should be a stronger acid than periodic acid (HIO4) because the electronegativity of the central atom increses as (Cl>B>I).

Acidic srength of acid as :  (HIO4)< (HBrO4)<(HClO4)

(2) For given non metal oxy acid the strength of oxy acid increases as the oxidation state of central atom increases for example; "HClO (+1),HClO2(+3), HClO(+5), HClO4(+7) 

Acidic srength of acid as :  (HClO)< (HClO2)<(HClO3)<(HClO4)

Relative  oxidizing character of oxy acid of Halogens:

Hypochlorous (HClO) act as the best oxidizing agent because it give nascent oxygen easily.

                                 HClOàHCl + O (nascent oxygen)

Order of oxiding character:  (HClO4)<(HClO3)<(HClO2)<(HClO)

Relative  thermal stability of oxy acid of Halogens:

As the number of pπ-dπ bond incrases bond strength incrases and thus order of thermal stability also increases.

Thermal stability order: (HClO)< (HClO2)<(HClO3)<(HClO4)

Relative (Cl-O) bond order and bond length

HOCI (0=Pπ-dπ bond)     BO=1

HOCIO (1=Pπ-dπ bond)  BO=1.5

HOClO2 (2=Pπ-dπ bond) BO=1.66

HOCIO3 (3=Pπ-dπ bond) BO=1.75

Hence (Cl-O) single bond length order as: (HClO)>(HClO2)>(HClO3)>(HClO4)

Question: which set of properties follow given order:

(HClO)< (HClO2)<(HClO3)<(HClO4)

(i) Acidic nature (ii) Oxidizing nature(iii) Thermal stability (iv) Cl-O single bond

(A) Only (i) (B) Only (i) & (iii) (C) Only (i), (iii) & (iii) (D) All of these

Answer Key: (B)

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"

Thursday, January 14, 2021

What are the oxy-acids?

Oxyacids:

The acids contains oxygen and must have one -OH group directly attach with central atom and also oxidation state of central atom is (+) positive. Most of covalent (acidic) oxide react with water to form oxy-acid that yield hydronium (H3O+)ions in solution. Mostly non metal of P-block formed oxy-acids except some metals.

Strength of Oxy acid:

The strenght of oxy acid define by degree of dissociation (pka) in water or ability to furnise H+ ions in water.

In general the relative strength of oxy acid can pridicted on the basis of electronegativity and oxidation state of central non metal atom.

(1) For example perchloric (HClO4) is stronger acid than sulphuric acid (H2SO4), which should be a stronger acid than phosphoric acid (H3PO4) because the electronegativity of the central atom increses as (Cl>S>P).

Acidic srength of acid as :  (HClO4)>(H2SO4)>(H3PO4)

(2) For given non metal acid the strength of oxy acid increases as the oxidation state of central atom increases for example sulphuric acid (OS=+6) (H2SO4) is more acidic then sulphurous acid (OS=+4)(H2SO3). Similarly nitric acis (HNO3)(OS=+5) is more acidic than Nitrous acid(HNO2)(OS=+3).

Acidic srength of acid as : 

(1) (H2SO4)>(H2SO3)

(2) (HNO3)> (HNO2)

(3) (HClO4)>(HClO3)>(HClO2)>(HClO)

Special Note: Oxy acid of phosphorous do not follow the concept of oxidation state. Because acidic strength of  phosphorous acid depends upon degree of dissociation (Ka or Pka value): the order  acidic nature follow as H3PO2 > H2PO3 > H3PO4

Levelling effect and relative strength of acids:

When strong acids like HClO4, HCl, HBr, HI, HNO3 etc are dissolved in water they are equally ionised (100%) it means they are equally strong in water this is called levelling effect of water.
Similarly for strong bases also , NaOH, KOH  Ca(OH)2 etc are in water behave the same. hence relative strength of strong acids or base can not be compare in water .
(1) Water does no show levelling effect for weak acids or base because they are ionised upto different extent in water.
(2) All the acids are stronger than H3O+ ion, consider as strong acids and weak than H3O+ ion are consider as weak acids.
(3) All the bases stronger than OH- are consider as strong base and weaker than OH-, then they are consider  as weak base.

Definition: If more than one acids or bases are showing same acidic or basic strength in same solvent it is called labelling effect and the solvent is called labelling solvent for example:

(1) HClO4 and HI equally dessociation in aqueous medium (99.99%)  it means they have equal strength.

(2) HCl, HNO3  and H2SO4 are equally strong in water because their strength are “levelled” to solvent species H3O+. only by putting them into a more acidic solvent do they weak acids. With determinate Pka values which differetiate their strengths. Thus in glacial ethanoic acid (acetic acid ) as solvent, the order of  acidic strength is as: H2SO4 > HCl > HNO3 .
(3) Similarly HF and HCl are equally dessociation in NaOH (100 %).
If their strength differ in same solvent ,it is called
differential effect and the solvent is called differential solvent.

(4) For example HClO4 dessociate 99.99 % in acetic acid while HI dissociate 99.8% in acetic acid, it means acidic strength of HClO4 is more than HI in acetic acid.

(5) Many of inorganic oxoacid are strong acid (with more negative Pka value) inaqueous solution. But, as we have seen, use of solvent with a lower proton affinity than water like acetic acid, makes it possible to differentiate between the strength of these acids and measure Pka value.

H2CO3 < H3PO4 < H2SO4 < HClO4 (Increasing acidic sterngth) these acidic strength can  also explain if the folmulae of the these oxy acids are written as base or OH formate or like that OC(OH)2 < OP(OH)3< O2S(OH)2< O3Cl(OH) then it is clear that the acidic strength incrases as the number of oxygen atoms not involve in O-H bonding increases.
The reason behind
levelling and diffential  effect is ability of solvent to donate or accept protons .
For acids, acidic solvents are differential and basic solvent are levelling.

 Related Questions:

What are "pyro" oxy acids?

What are "Ortho" or "Meta" oxyacids?