`ZnO` : It is called as phillospher's wool due to its wooly flock type appearance.

`text(Preparation)` : (i) `2Zn + O_2 -> 2ZnO`

(ii) `ZnCO_3 -> ZnO + CO_2`

(iii) `2Zn(NO_3)_2 -> 2ZnO + 4NO_2 + O_2`

(iv) `Zn(OH)_2 -> ZnO + H_2O`

`text(Purest) ZnO` : `4ZnSO_4 + 4Na_2CO_3 + 3H_2O -> undersettext(white basic zinc carbonate)[ZnCO_3*3Zn(OH)_2] downarrow + 4Na_2SO_4 + 3CO_2`

`ZnCO_3*3Zn(OH)_2 overset(Delta)-> undersettext(Pure)(4ZnO) + 3H_2O uparrow + CO_2 uparrow`

`text(Properties)` :

(i) `undersettext(white)(ZnO)(cold) overset(Delta) ⇋ underset(yellow)(ZnO)(hot)`

(ii) It is insoluble in water.

(iii) It sublimes at `400^oC`.

(iv) It is amphoteric oxide.

`ZnO + 2HCl -> ZnCl_2 + H_2O`

`ZnO + H_2SO_4 -> ZnSO_4 + H_2O`

`ZnO + 2NaOH -> Na_2ZnO_2 + H_2O`

(v) `ZnO -> Zn` by `H_2` & `C`

`ZnO + H_2 overset(> 400^oC)-> Zn + H_2O`

`ZnO + C -> Zn +CO`

(vi) It forms Rinmann's green with `Co(NO_3)_2`

`2Co(NO_3)_2 -> 2CoO + 4NO_2 + O_2`

`CoO + ZnO -> undersettext(Rinmann's green)(CoZnO_2)` or `CoO- ZnO`

`text(Uses)` :

(i) As white pigment. It is superior than white lead because it does not turn into black.

(ii) Rinmann's green is used as green pigment.

(iii)It is used as zinc oinnnent in medicine.

`(ZnCl_2)` :

`text(Preparation)` :

`ZnO + 2HCl -> ZnCl_2 + H_2O`

`ZnCO_3 + 2HCl -> ZnCl_2 + H_2O + CO`

`Zn(OH)_2 + 2HCl -> ZnCl_2 + 2H_2O`

`ast ZnCl_2` recrystallises as `ZnCl_2. 2H_2O`.

Anh. `ZnCl_2` cannot be made by heating `ZnCl_2*2H_2O` because

`ZnCl_2*2H_2O overset(Delta) -> Zn(OH)Cl + HCl + H_2O`

`Zn(OH)Cl overset(Delta) -> ZnO + HCl`

To get anh. `ZnCl_2` : `Zn + Cl_2 -> ZnCl_2`

`Zn + 2HCl text(dry) -> ZnCl_2 + H_2`

or `Zn + HgCl_2 -> ZnCl_2 + Hg`

`text(Properties)` : (i) It is deliquescent white solid (when anhydrous).

(ii) `ZnCl_2 + H_2S -> ZnS`

`ZnCl_2 + NaOH -> Zn(OH)_2 oversettext(excess)-> Na_2[Zn(OH)_4]`

`ZnCl_2 + NH_4OH -> Zn(OH)_2 oversettext(excess)-> [Zn(NH_3)_4]^(2+)`

`text(Uses)` : (i) Used for impregnating timber to prevent destruction by insects.

(ii) As dehydrating agent when anhydrous.

(iii) `ZnO*ZnCl_2` used in dental filling.

`(ZnSO_4)` :

`text(Preparation)` `->`

`Zn + text(dil) H_2SO_4 -> ZnSO_4 + H_2`

`ZnO + text(dil) H_2SO_4 -> ZnSO_4 + H_2O`

`ZnCO_3 + text(dil) H_2SO_4 -> ZnSO_4 + H_2O + CO_2`

`ZnS+ 2O_2 -> ZnSO_4`

`ZnS +2 O_2 -> ZnO`

`ZnS + 4O_3 -> ZnSO_4`

`text(Properties)` : (i) `ZnSO_4. 7H_2O overset(39-70^oC)-> ZnSO_4 * 6H_2O overset(> 70^oC)-> ZnSO_4*H_2O overset(>280^oC)-> ZnSO_4 overset(> 800^oC)-> 1/2 O_2 + SO_2 + ZnO`

`text(Uses)` : (i) in eye lotion.

(ii) Lithophone making (`ZnS + BaSO_4`) as white pigment.

`CuO` :

`text(Preparation) ->`

(i) `undersettext[Malachite Green(native Cu- carbonate)][CuCO_3. Cu(OH)_2] -> 2CuO + H_2O + CO_2` (Commercial process)

(ii) `2Cu + O_2 -> 2CuO & Cu_2O + 1/2 O_2 -> 2CuO`

(iii) `Cu(OH)_2 overset(Delta)-> CuO + H_2O`

(iv) `2Cu(NO_3)_2 overset(250^oC)-> 2CuO + 4NO_2 + O_2`

`text(Properties)` `->`

(i) `CuO` is insoluble in water.

(ii) Readily dissolves in dil. acids

`CuO + H_2SO_4 -> CuSO_4 +H_2O`

`CuO + 2HCl -> CuCl_2 +H_2O`

`CuO + 2HNO_3 -> Cu(NO_3)_2 + H_2O`

(iii) It decomposes when, heated above `1100^oC`

`4CuO -> 2Cu_2O + O_2`

(iv) `CuO` is reduced to `Cu` by `H_2` or `C` under hot condition

`CuO + C-> Cu +CO uparrow`

`CuO + H_2 -> Cu + H_2O uparrow`

`CuCl_2` :

`text(Preparation)` : `CuO + 2HCl(conc.) -> CuCl_2 + H_2O`

`Cu(OH)_2*CuCO_3 + 4HCl -> 2CuCl_2 + 3H_2O + CO_2`

`text(Properties)` `->`
(i) It is crystallised as `CuCl_2*2H_2O` of Emerald green colour.

(ii) dil. solution in water is blue in colour due to formation of `[Cu(H_2O)_4]^(2+)` complex.

(iii)conc. `HCl` or `KCl` added to dil. solution of `CuCl_2` the colour changes into yellow, owing to the formation of `[CuCl_4]^(2-)`.

(iv)The conc. aq. solution is green in colour having the two complex ions in equilibrium

`2[Cu(H_2O)_4]Cl_2 ⇋ [Cu(H_2O)_4]^(2+) + [CuCl_4]^(2-) + 4H_2O`

(v) `CuCl_2 -> CuCl` by no. of reagents

(a) `CuCl_2 + Cu`-turnings `overset(Delta)-> 2CuCl`

(b) `2CuCl_2 + H_2SO_3 + H_2O -> 2CuCl + 2HCl + 2H_2SO_4`

(c) `2CuCl_2 + Zn//HCl -> 2CuCl + ZnCl_2`

(d) `CuCl_2 + SnCl_2 -> CuCl + SnCl_4`

`=>` `CuF_2*2H_2O ->text(light blue)`

`CuCI_2*2H_2O -> text(green)`

`CuBr_2 -> text(almost black)`

{Anh. `CuCl_2` is dark brown mass obtained by heating `CuCI_2*2H_2O` at `150^oC` in presence of `HCl` vap.}

`CuI_2` does not exist `CuCl_2*2H_2O` `underset[HCl text(gas)] overset[150^oC] -> CuCl_2 + 2H_2O`

`CuSO_4` :

`text(Preparation)` : `CuO + H_2SO_4text[(dil)] -> CuSO_4 + H_2O`

`Cu(OH)_2 + H_2SO_4 text[(dil)] -> CuSO_4 + 2H_2O`

`Cu(OH)_2*CuCO_3 + H_2SO_4 text[(dil)] -> CuSO_4 + 3H_2O + CO_2`

`undersettext(Scrap)(Cu) + H_2SO_4 + 2O_2 -> CuSO_4 + H_2O` [Commercial scale]

`Cu + text(dil.) H_2SO_4 ->` `text(no reaction)` {`Cu` is below `H` in electrochemical series}

`text(Properties)` : (i) lt is crystallised as `CuSO_4*5H_2O`.

(ii) `undersettext(Blue)(CuSO_4*5H_2O) oversettext(On expouser)undersettext(efforesence take places)⇋ undersettext(Pale blue)(CuSO_4. 3H_2O) overset(100^oC)⇋ undersettext(Bluish white)(CuSO_4*H_2O) overset(230^oC)⇋ CuSO_4text[(anh.)]`

`text(Preparation)` : (i) `text(Scrap) Fe + H_2SO_4 -> FeSO_4 + H_2S uparrow`

(ii) From Kipp's waste

`FeS + H_2SO_4(dil.) -> FeSO_4 + H_2S uparrow`

(iii) `FeS_2 + 2H_2O + 7/2 O_2 -> FeSO_4 + H_2SO_4`

`text(Properties)` : (i) It undergoes aerial oxidation forming basic ferric sulphate.

`4FeSO_4 + H_2O + O_2 -> 4Fe(OH)SO_4`

(ii) `FeSO_4 *7H_2O overset (300^oC)-> FeSO_4 undersettext(temp) oversettext(high) -> Fe_2O_3 + SO_2 +SO_3`

(iii) Aq. solution is acidic due to hydrolysis.

`FeSO_4 + 2H_2O ⇋ undersettext(weak base)[Fe(OH)_2] + H_2SO_4`

(iv) It is a reducing agent.

(a) `Fe^(2+) + MnO_4^(-) + H^(+) -> Fe^3+ + Mn^2+ + H_2O`

(b) `Fe^(2+) + Cr_2O_7^(2-) + H^(+) -> Fe^(3+) + Cr^(+) + H_2O`

(c) `Au^(3+) + Fe_2 -> Au + Fe^(3+)`

(d) `Fe^(2+) + HgCI_2 -> Hg_2Cl_2 downarrow + Fe^(3+)`

(v) It forms double salt. Example `(NH_4)_2SO_4*FeSO_4*6H_2O`

`FeOquadtext(Black)`

`text(Preparation)` : `FeC_2O_4 oversettext(in absence of air)-> FeO +CO+ CO_2`

`text(Properties)` : It is stable at high temperature and on cooling slowly disproportionates into `Fe_3O_4` and iron

`4FeO -> Fe_3O_4 + Fe`

`FeCl_2` :

`text(Preparation)` : `Fe + 2HCl undersettext(a current of HCl) oversettext(heated in) -> FeCl_2 + H_2`

`2FeCl_3 + H_2 overset(Delta)-> 2 FeCl_2 +2HCl`

`text(Properties)` : (i) It is deliquescent in air like `FeCl_3`.

(ii) It is soluble in water, alcohol and ether also because it is sufficiently covalent in nature.

(iii) It volatalises at about `1000^oC` and vapour density indicates the presence of `Fe_2CI_4` . Above `1300^oC` density becomes normal.

(iv) It oxidises on heating in air

`12FeCl_2 + 3O_2 -> 2Fe_2O_3 + 8FeCI_3`

(v) `H_2` evolves on hearing in steam

`3FeCl_2 + 4H_2O -> Fe_2O_4 + 6HCl + H_2`

(vi) It can exist as different hydrated form

`FeCl_2*2H_2O ->` `text(colourless)`

`FeCI_2*4H_2O ->` `text(pale green)`

`FeCI_2*6H_2O ->` `text(green)`

`FeCl_3` :

`text(Preparation)` : Anhydrous ferric chloride is prepared by heating metallic iron in a stream of dry chlorine gas.

(i) `FeCl_3` solid is almost black. It sublimes at about `300-C`, giving a dimeric gas.

(ii) `FeCl_3` dissolves in both ether and water, giving solvated monomeric species.

(iii) Iron (`lll`) chloride is usually obtained as yellow-brown lumps of the hydrate `FeCl_3*6H_2O`.

(iv) This is very soluble in water and is used both as an oxidizing agent, and as a mordant in dyeing.

(v) `FeCl_3` is also used in the manufacture of `C Cl_4`.