Compounds of Lead

Compounds of Lead

Compounds of Lead

  1. Lead monoxide, PbO (Litharge)

    Preparation: It is obtained by heating lead or lead sulphide in air.

    2Pb + O2 2PbO

    2PbS + 3O2  2PbO + 2SO2

    Properties:
     
    1. It is insoluble in water.

    2. It is an amphoteric oxide.

      PbO + 2HNO3  Pb(NO3)2 + H2O

      PbO + 2NaOH  Na2PbO+ H2O

    3. On heating in air at 470C, it forms red lead.

      6PbO + O2  2Pb3O4
       
  2. Read lead, Pb3O4

    Preparation: It is obtained by heating litharge at 470oC in air 

    6PbO + O—> 2Pb3O4

    Properties:
     
    1. It is a red powder, insoluble in water.

    2. On heating above 470oC, it decomposes.

      2Pb3O4  6PbO + O2

    3. When treated with conc. HNO3 acid, lead nitrate and brownish black insoluble oxide, PbOis formed.

      Pb3O+ 4HNO3  2Pb(No3)+ PbO2 + 2H2

    4. With H2SO4, it envolves oxygen.

      2Pb3O4 + 6H2SO4  6PbSO+ 6H2O + O2

    5. It acts as an oxidising agent.

      Pb3O+ 8HCl3PbCl2 + 4H2O + Cl2

      Pb3O4 + 4C3Pb + 4CO

      Pb3O4 + 4CO3Pb + 4CO2
       
  3. Lead (ii) halides (PbX2)

    Preparation: It is prepared by adding an aqueous solution of a suitable halide to soluble lead (II) salts, 

    Pb(NO3)2 + 2NaX  PbX2 + 2NaNO3

    (where X = F, Cl, Br or l)

    Properties:
     
    1. All the lead dihalides except Pblare white crystalline solids. (Pbl2 : yellow)

    2. All the lead dihalides are quite stable.

    3. All the dihalides are some what ionic in character. Their ionic character, however decreases with the increase in the size of the halogen atom.

      PbF2 > PbCl2 > PbBr> Pbl2

  4. Lead tentrahalides (PbX4)

    PbF4 and PbCl4 are quite stable, Pbl4 are, however unknown. The ions Brand l- are reducing agents i.e., in presence of these ions Pb4+ ions are reduced to Pb2+ ions.

    Preparation:

    1. PbF4 is prepared by the action of BrF3 on lead dioxide.

      3PbO2 + 4BrF3  3PbF4 + 2Br2 + 3O2

    2. PbClis prepared by dissolving lead dioxide in conc. HCl at 273 K.

      PbO2 + 4HCl  PbCl4 + 2H2O

    Properties:
     

    1. PbF4 is white solid and PbCl4 is a volatile liquid.

    2. PbF4 is more stable than PbCl4.

      PbCl4  PbCl+ Cl2

    3. PbFis not easily hydrolysed by water but PbCl4 is rapidly hydrolysed by water.

      PbCl4 + 2H2 PbO+ 4HCl.

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