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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"

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