Chemistry PREPARATION, PROPERTIES, STRUCTURES AND USES OF OXYGEN MOLECULE AND OZONE

Compounds of Oxygen :

Following are the compounds of oxygen :

Oxygen Molecule (`O_2`) :

(i) In air as `O_2` to the entent of `21%` by volume or `23%` by weight.

(ii) Lab method to produce `O_2` is

`2NaO_2 + 2H_2O -> 4NaOH + O_2`

(iii) Air is liquefied by use of joule-Thomson effect {cooling by expansion of gas}.

(iv) `text(Reaction with compounds :)`

(a) Contact Process :

`2SO_2 + O_2 oversettext(Pt. asbestos)-> 2SO_3`

(b) Ostwald Process :

`4NH_3 + 5O_2 oversettext(Pt. Gauze)-> 4NO + 6H_2O`

(c) Deacon's Process :

`4HCl + O_2 undersettext(chloride)oversettext(cupric)-> 2Cl_2 + 2H_2O`.

(v) `text(Uses :)`

(a) Oxy-Acetylene flame is used for cutting process and welding process.

(b) Liquid oxygen is a constituents of fuels used in rockets.

`ast` `text(Oxides :)` A binary compound of oxygen with another element is called an oxide.
(a) Oxygen combined nearly with all other elements except inert gases, noble metals and halogens.

(b) The binary compounds of oxygen with other element are called oxides. Hence, the compounds of oxygen and fluorine `(OF_2, O_2, F_2)` are not called as oxides.

Ozone :

Unstable deep blue, diamagnetic gas, with fishy smell. Toxic enough (more toxic than `KCN`). It's intense blue colour is due to the absorption of red light.

`2F_2 + 2H_2O -> 4HF + O_ 2 text(Ozonised oxygen)`

`F_2 + 3H_2O -> 6HF + O_3 text(Ozonised oxygen)`

These are separated by passing into spiral tube cooled into liquid air. Ozone condenses at `-112.4^oC`.

[b.p. of `O_2` `-183^oC`; b.p. of liq. air is `-190^oC`]

`text(Oxidising property of)` `O_3` :

It is one of best oxidising agent, in acid solution, its standard, reduction potential value is `2.07` `V`.

`O_3 + 2H^(+) + 2e -> O_ 2 + H_2O` `E^o = +2.07` `V`

It is next to `F_2` [above `2.07` `V`, only `F_2`, `F_2O` are there]

(i) Metal Sulphides to Sulphates

`MS + 4O_3 -> MSO_4 + 4O_2` [`M = Pb, Cu, Zn, Cd`]

(ii) `2HX + O_3 -> X_2 + H_2O + O_2` [`X = Cl, Br, I`]

(iii) Moist `S`, `P`, `As` + `O_3 =>`

`S + H_2O + 3O_3 -> H_2SO_4 + 3O_2`

`2P + 3H_2O + SO_3 -> 2H_3PO_4 + SO_2`

`2As + 3H_2O + SO_3 -> 2H_3AsO_4 + SO_2`

(iv) {`KI + 3O_3 -> KIO_3 + 3O_2`} alk.

{`KI + 4O_3 -> KIO_4 + 4O_2`} alk.

(v) `Hg` loses its fluidity(tailing of `Hg`)

`2Hg + O_3 -> Hg_2O + O_2`

similarly `2Ag + O_3 -> undersettext(Brown)(Ag_2O) + O_2`

(vi) `BaO_2 + O_3 -> BaO + 2O_2`

`H_2O_2 +O_3-> H_2O + 2O_2`

`Na_2O_2 + O_3 + H_2O -> 2NaOH + 2O_2`

`text(Absorbent :)` (i)Turpentine oil

(ii) Oil of cinnamon

`text(Uses :)`

(i) Sterilising water

(ii) Detection of position of the double bond in the unsaturated compound.

`text(Classification of oxides)`

(a) Acidic oxides `-> H_2O + CO_2 -> H_2CO_3`

e.g. `CO_2`, `B_2O_3`, `SiO_2`, `N_2O_3`, `NO_2`, `N_2O_5`, `P_4O_6`

`text(Note :)` Mixed anhydrides `->` Those oxides which form two oxy acids.

e.g. `2NO_2 + H_2O -> HNO_2 + HNO_3`

`P_4O_8 + 6H_2O -> 2H_3PO_3 + 2H_3PO_4`

`SiO_2 + 2NaOH -> undersettext(Salt)(Na_2SiO_3) + undersettext(water)(H_2O)`


(b) `text(Basic oxides :)`

Oxide `+ H_2O ->` alkali ; e.g. `Na_2O + H_2O -> 2NaOH`

Oxide + acid `->` salt `+ H_2O` ; e.g. `CuO + H_2SO_4 -> CuSO_4 + H_2O`

Oxide + Acidic oxide `->` salt ; e.g. `PbO + SO_3 -> PbSO_4` .

(c) `text(Neutral Oxide :)`

Oxide + Acid `->` No reaction

Oxide+ Base `->` No reaction

e.g. `CO, H20 , N20 , NO` etc.

(d) `text(Amphoteric oxides)` `->` React with acid & base both to form salts.

e.g. `ZnO, Al_2O_3, BeO, SbO_3, Cr_2O_3, PbO, PbO_2` etc.

`ZnO + 2NaOH -> Na_2ZnO_2 + H_2O; ZnO + 2HCl -> ZnCl_2 + H_2O`

`Al_2O_3 + 2NaOH -> 2NaAlO_2 + H_2O ; Al_2O_3 + 6HCl -> 2AlCl_3 + 3H_2O`

`PbO + 2NaOH -> Na_2PbO_2 + H_2O ; PbO + H_2SO_4 -> PbSO_4 + H_2O`

`Cr_2O_3 + 2NaOH -> Na_2Cr_2O_7+H_2O ; Cr_2O_3 + 3H_2SO_4 -> Cr_2(SO_4)_3 + 3H_2O`

(e) `text(Compound or mixed oxides)` `->` Oxides which behaves as mixture of two simple oxides.

e.g. `Pb_3O_4 (2PbO + PbO_2)`

`Fe_3O_4 (FeO + Fe_2O_3)`

`Mn_3O_4 (2M nO + MnO_2)`

(f) `text(Peroxides)` `->` Oxides + dil acids `-> H_2O_2`

e.g. `Na_2O_2 + H_2SO_4 text(dil) -> Na_2SO_4 + H_2O_2`

`BaO_2 + H_2SO_4 text(dil) -> BaSO_4 + H_2O_2`

(g) `text(Dioxides)` `->` Like peroxides, these also contain excess of oxygen but do not form `H_2O_2` with dilute acids. They evolve chlorine with conc. `HCl` and oxygen with conc. `H_2SO_4`.

e.g. `-> PbO_2, MnO_2`

`MnO_2 + 4HCl` `text(conc.) -> MnCl_2 + Cl_2+ 2H_2O`

`2MnO_2 + 2H_2SO_4 text(conc.) -> 2MnSO_4 + O_2 + 2H_2O`

(h) `text(Suboxides)` `->` The oxides which contain less oxygen than expected from the normal valency of the elements are termed sub-oxides.

e.g. Carbon suboxide - `C_3O_2`

Lead suboxide - `Pb_3O`

Nitrous oxides - `N_2O`

(i) Superoxides `->` These oxides contain `O_2^(-)` ion.

e.g. `KO_2, RbO_2, CsO_2`

These react with water to give hydrogen peroxide and oxygen.

`2KO_2 + 2H_2O -> 2KOH + H_2O_2 + O_2`


 
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