Oxoacids of halogens - class-XII

Oxygen florides forms $HF,O _2$ on hydrolysis.

$OF _2 + H _2O\rightarrow O _2 + 2 HF$

$2O _2F _2 + 2H2O\rightarrow O _2 + 4HF$

so oxygen florides do not form forms hypohalous acids.

So the given statement oxygen florides forms oxoacids is wrong.

Hence option C is correct.

Bleaching powder is $Ca(OCl)Cl$.

Hypochlorite radical is represented as $ClO^-$. Thus the given statement is false.

Chlorous acid = $\overset{+1\ +3\ -4}{HClO _{2}}$
Let oxidation state of chlorine be x.
$\therefore{x}+1+2(-2)=0$
Here oxidation state of oxygen is -2 and that of hydrogen is +1.
$\therefore x=+3$
oxidation state in chlorous acid of chlorine is +3.

$\overset{+1}{K}Cl\overset{-2}{O}$
oxidation state of alrali metals = +1
oxygen = -2

Bleaching powder is also called calcium chlorohypochlorite because it is considered as a mixed salt of hydrochloric acid and hypochlorous acid. 

The chemical formula of bleaching powder is $CaOCl _{2}$. Here, calcium is bonded to $Cl^{-}$ ion and $OCl^{-}$ ion respectively.

$HCIO _4$ has highest oxidation state of chlorine i.e + 7

Chlorine water
$CI _2+H _2O \rightarrow HOCI+HCI$

$NaClO$ has the maximum $pH$ because the acidic strength decreases with decreasing $O$ atoms in oxy acids . Since $NaClO$ has the lowest oxygen atom among given options, it will have least acidic strength and hence, a maximum $pH$.

$(A)$ In $Cr _2{O _7}^{2-}$, the oxidation state of $Cr$ is $+6$, which is maximum oxidation of $Cr$. It can only lower down its oxidation state. So, it acts only as an oxidising agent.
$(B)$ In $N{O _3}^{-}$, the oxidation state of $N$ is $+5$, which is the maximum oxidation of $N$. It can only lower its oxidation state  and so, it acts only as an oxidising agent.
$(C)$ In $OCl^-$, the oxidation state of $Cl$ is $+1$ and $Cl$ shows oxidation state from $-1$ to $+7$ and so, it can undergo both oxidation and reduction.
$(D)$ In ${S}^{2-}$, the oxidation state of $S$ is $-2$, which is the minimum oxidation state of $S$ and so, it can only increase its oxidation state and hence, it acts only as a reducing agent.

The basicity of oxoanions is inversely related to the stability of the conjugate acid. ClO- is the conjugate base of the weakest acid (HClO), making it the strongest base in the series. As the oxidation state of chlorine increases (from ClO- to ClO4-), the conjugate acid becomes stronger, making the anion a weaker base.

HF has a highest boiling point due to strong H bonding.
$Cl _2$ has a lowest boiling point due to lowest molar mass.
$CO$ has highest dipole moment due to linear structure.

Reaction of process:

A peroxy acid is an acid which contains an acidic -OOH group. $HClO _4$ doesn't contain -OOH group.

The formula for calcium chlorite is $ Ca(ClO _2) _2 $.Calcium chlorite appears as white granular solid.

A. The oxides of chlorine such as $ClO _2$  and $Cl _2O$ are used as bleaching agents for paper pulp and textiles. Thus, the option A is correct.

 The acidic strength of the hypohalous acids increases in the order  : HOI <HOBr <HOCl < HOF.

A. During the conversion of $BrO^- _3\ to\ BrO^- _4$, the oxidation number of bromine changes from +5 to +7. Hence, the option A is incorrect.
B. and C.  Since there is an increase in the oxidation number, the net reaction is the oxidation of bromine. Hence, the options B and C are incorrect.
D. The equivalent mass of $BrO^- _3$ is the ratio of the ionic mass to the change in the oxidation number. It is tone half of the ionic mass as the change in the oxidation number is 2. Thus, the option D is correct.

The dielectric constant is the ratio of the permittivity of a substance to the permittivity of free space. It is an expression of the extent to which a material concentrates electric flux, and is the electrical equivalent of relative magnetic permeability.
As the dielectric constant increases, the electric flux density increases, if all other factors remain unchanged. This enables objects of a given size, such as sets of metal plates, to hold their electric charge for long periods of time, and/or to hold large quantities of charge. 
Due to higher electronegativity constituent atoms, $FClO _3$ have very high dieelectric constant.

Conjugate base of $HClO, HClO _2, HClO _3, HClO _4$ are  $CLO^-, {ClO _2}^-, {ClO _3}^-, {ClO _4}^-$.

As we move down the group basic nature of hydroxides of halogens increases so correct order of decreasing acid strength of hydroxides of halogens is I > II> III
Hence option A is correct.

$ClO _4^-$
+7
here, Cl is in highest oxidation state so further it can not be oxidise so it can not undergo disproportionation reaction.

For the same oxidation state, when the electronegativity of the halogen increases, the strength of the oxyacid increases.
$HOCI > HOBr > HOI$

In fluorine d-orbitals are absent so it shows only +1 oxidation state in oxo-acid,
but not + 3, + 5 or + 7. 

$H\overset{+7}{Cl}O _4$ is strongest oxidising agent.
as Cl is in its highest oxidation state, i.e., +7.
Oxidation state $\alpha$ Oxdising nature 

$\overset{+7}{HClO _{4}}$ a is in highest oxidation state so its oxidizing nature is least.

oxidation state $\alpha$ $\frac{1}{oxidising \ nature}$

There are also other halous acids like:
$HOBr _2$ which is Hydrobromous acid.
So D is wrong

$2HClO _4\ \overset{-H _2O}{\rightarrow}Cl _2O _7$
$\therefore $  Anhydride of $2HClO _4$ is $Cl _2O _7$

$NaCl^{-1}$
$NaOCl^{+1}$ - most basic as Cl is in +1 oxidation state and on hydrolysis it gives weak acid HOCl. Thus it is most basic among the given compounds.
$\overset{+3}{NaClO _{2}}$
$\overset{+5}{NaClO _{3}}$

Bond order $\propto \ \frac{1}{Bond\ length}$

Number of valence electrons present in atoms of $HClO _{4},HClO _{3},HClO _{2}$ are32,26,20 respectively.
Number of valence electrons present in atoms of  $HClO _{4}$ are $1+7+4(6)=32$
Number of valence electrons present in atoms of  $HClO _{3}$ are $1+7+3(6)=26$
Number of valence electrons present in atoms of  $HClO _{2}$ are $1+7+2(6)=20$

As the number of oxygen atoms in hypochlorous acid increases the thermal stability increases so $HClO _4$ is the most stable thermally.

The correct formula for the chlorate ion is $Cl{O} _{3}^{-}$
The formula $Cl{O}^{-}$ represents hypochlorite ion.
The formula $Cl{O} _{2}^{-}$ represents chlorite ion.
The formula $Cl{O} _{4}^{-}$ represents perchlorate ion.

$HIO _3$  most stable among the given acids because it do not ionize itself easily.

$KClO _3 + 6HCl + I _2 \rightarrow 2ICl _3 + KI + 3H _2O$ 

Calcium oxychloride ($CaOCl _2$) is known as bleaching powder. When it is treated with excess of dilute acids, chlorine is evovled which is responsible for the bleaching action of bleaching powder. Due to the evolution of nacent oxygen, it acts an an oxidising and bleaching agent.

$ KClO _3 $- Explosives.May explode under prolonged exposure to heat or fire.

The anyhdride of $HOCl$ is $Cl _2O$.
The anyhdride of $HClO _2$ is $ClO _2$.
The anyhdride of $HClO _3$ is $Cl _2O _6$.
The anyhdride of $HClO _4$ is $Cl _2O _7$.
Anhydrides on reaction with water will give you corresponding acid.

(a) hypochlorous acid +1
(b) chlorous acid +3
(c) hypobromous acid +1
(d) bromic acid +5
(e) periodic acid +7
(f) perchloric acid +7

1. The reduction potential values are as follows:
   $ClO _4^-: 1.19\ V$,
   $BrO _4^-: 1.65\ V$,
   $BrO _4^-: 1.74\ V$.
   So, the order of oxidising power is: $ClO _4^- < IO _4^- < BrO _4^-$.
   2) The correct order of acidic strength is: $HOCl < HOBr < HOI$. As the electronegativity of halogens increases, the acidic character also increases.
   

1. Disproportionation is a specific type of redox reaction in which a species is simultaneously reduced and oxidised to form two different products.

   Here the $ClO^{-}$ is simultaneously reduced and oxidised to form two different products.

   
   

   Hence option C is correct.

When bleaching powder is treated with mineral acids ${ Cl } _{ 2 }$ gas evolved

Halogen are treated with hot and conc. alkalis, major products formed are Halate and halide.

Calcium hydroxide react with chlorine to give calcium hipochlorite, calcium chloride and water. Calcium hipochlorite which is formed in the reaction is used as bleaching agent, disinfevtant and in the sterilization process.

$2Ca(OH) _2 + 2Cl2 \rightarrow Ca(ClO) _2 + CaCl _2 + 2H _2O$.

Hence option A,B,C are correct.

The anions given are conjugate bases of acids. According to Lowry Bronsted concept, a strong acid has weak conjugate base and a weak acid has a strong conjugate base. These anions are stabilised to greater extent, it has lesser attraction for proton and therefore, will behave as weaker base (lesser tendency for the reaction to go in backward direction). Consequently, the corresponding acid will be strongest because weak conjugate base has strong acid and strong conjgate base has weak acid and vice versa. The charge stabilization increases in the order : $ClO^- < ClO _2^- < ClO _3^- < ClO _4^-$. This means that $ClO^-$ will have minimum stability and therefore, will have maximum attraction for $H^+$. In other words $ClO^-$ will be strongest base and so its conjugate acid HClO will be the weakest acid.

The thermal stability of the oxyacids of halogens increases with increase in the oxidation state of halogen or with increase in the number of oxygen atoms.
 This is due to involvement of more electrons in the formation of sigma and pi bonds. The multiplicity of the Cl-O bond increases.
Thus the increasing order of the thermal stability is $HClO <HClO _2 <HClO _3<HClO _4$. Thus, $HClO _4$ is most stable to heat.

$HClO _4$ is the strongest oxidizing agent as the oxidation number of chlorine in $HClO _4$ is +7 and it can't afford to lose any more electron.

Perchloric acid (HClO4) is more stable than chloric acid (HClO3) because the perchlorate ion (ClO4-) has greater resonance stabilization due to the higher number of oxygen atoms distributing the negative charge.

The overlap become better when the overlapping orbitals have comparable energy. The extent of overlap between orbitals with huge energy difference is insignificant.

 Disproportionation reaction of chlorous acid is given as :

Higher the I.E, higher the acidic strength of hypohalus acid (hydroxides)

Let us calculate the oxidation state of Cl in $HClO _4$ ;

Bleaching powder reacts with carbon dioxide in air to give chlorine and calcium carbonate.

The acidic character of oxyacids increases with increase in the oxidation state.