LEAD - A Transition Metal
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Transcript of LEAD - A Transition Metal
LEAD(Plumbum)
Pb
LEAD
Chemical symbol : Pb Atomic number : 82 Atomic weight : 207.2 Group no.: 14 (or IVa) Element of origin name:
Anglo-Saxon lead
82
Pb
HISTORY Lead has been commonly used for
thousands of years ago. Came from the Latin word “plumbum” Lead was mentioned on the Book of
Exodus (15:10)
“But you blew with your breath,
and the sea covered the
They sank like lead in the mighty water”
In alchemy , lead was thought to be the oldest metal associated with the planet Saturn.
Romans used lead in the molten form to secure iron pins that held together large limestone blocks in a certain monumental building.
SOURCES OF LEAD
Galena(PbS)
is a grayish-black cubic crystals which is
composed of 86% Pb and 13.5% S. It is the principal
ore of lead.
Cerrusite (PbCO3 )
Is a colorless, white or gray ore which is
composed of 83.5% of PbO and 16.5 % of CO2
It is also known as white lead ore.
PbSO4
is a colorless, white gray, pale shades of
yellow; colored dark gray by impurities which
composed of 73% PbO and 26.4% SO3
PHYSICAL PROPERTIES
Malleable and ductile Easy to scratch and cut Has a little tensile strength Corrosion resistant Melts at 327 oC Boils atb1750 oC Specific gravity: 11.45
CHEMICAL PROPERTIES Exhibit variety of oxidation number (+2,+4) Reaction with air
2Pb + O2 2PbO
Reaction with dilute acid
2Pb + H2SO4 PbSO4 + H2
Reaction with organic acid
Pb + 2CH3COOH Pb(CH3COOH)2+ H2
Reaction with pure H2O in the presence of O2
2Pb + 2H2O + O2 2Pb(OH)2
Reaction with pure H2O in the presence of CO2
3Pb + 2CO2 + 4H2O Pb3(OH)2(CO3)2 + H2O
ADDITIONAL INFORMATIONMetallic lead is resistant to the action of dilute to moderately concentrated solution of sulfuric acid because of the formation of coatings of insoluble lead sulfate.Hard water does not affect lead because of the formation of surface layer of insoluble compound of PbSO4, bicarbonate and other anion that is usually present in hard water .
CRUSHER
GRINDER
ore
Crushed ore
Ground ore
Xanthale rgt.
air gangue
ROASTER
froth
SO2
air
Unroasted (PbS)PbSO4
PbO
Reactions: At the Roaster:
2PbS + 3O2 2PbO + 2SO2
2PbS + 2O2 PbSO4
Extraction process
BLAST FURNACE
MELTER
COOLER
Unroasted (PbS)
PbSO4
PbO
Crude Pb
SO2,CO2,CO, FeS
SlagCaSiO3
Coke, scrap Fe, CaCO3
I. Spark ProcessA. Removal of Cu, Sb, As and
Bi
Melted Pb
Crystallized Cu
Oxides of Sb, As, Bi
(skimmed off)
Blast air
Reaction at the Blast furnace
2PbO + PbS 3Pb + 2SO2
PbSO4 + PbS 2Pb + 2SO2
PbO + C Pb (s) + COPbO + CO Pb (s) + CO2PbS+ Fe Pb (s) + FeS (g)
Pb free of Sb, As and
Bi
MELTERELECTRO-REFINERY
B. Removal of Au and Ag.
Pb free of Sb, As and Bi
Au and Ag
dissolve in Zn
zinc
II. Betts Process
High purity Pb metal
Impure lead
Applications Major constituent of lead acid storage battery. Used as a coloring pigment. Used as sound deadening layer. Used as solder for electronics. Use as roofing materials. Used as shield against radiations. Used as a pigment in lead paint for white as well as
yellow and red color.
Alloys
A. Perforated grids in storage battery
- 4% Pb, 12% Sb, 0.25% Sn and small amount of arsenic, silver and copper.
B. Solder
- 50 % Sn and 50% Pb.
C. Bearing Metal
-10% -90% Pb with Sn, Sb, and Cu.
D. Type metals
- example is the metal in the linotype machine composed of 84.5% lead, 45% tin and 11.5% antimony.
- used in printing industry.
E. Pewter
- 1%-50% Pb and Sn
II
Sheet lead is used for making the chambers of sulfuric plants for which it is chemical inactivity make it suitable. Also used as a roofing material.
Lead foil is used for lining tea chests, and as as substitute for tin foil.
Lead shot is usually has 1 % arsenic added to make lead harder.
Lead pipe is used for sink traps and waste pipes.
Important Compounds Lead (II) oxide (PbO) or litharge
a red or reddish yellow solid used in making glass, paint and varnish industry.
Lead (IV) oxide (PbO2)
a brown color substance and forms the active material of the positive plate of lead storage battery.
Lead (II,IV) oxide (2PbO.2PbO2)
known as red lead, used as a protective pigment of paint for iron and steel.
Lead (II) acetate (Pb(C2H3O2)2)
white crystalline used as white lead and to treat poison ivy poisoning.
Lead (II) chromate PbCrO4
chrome yellow used as a yellow pigment. Lead (II) arsenate Pb3(AsO3)2
called as arsenate lead. White colored substance, used as an insecticide.
Basic lead (II) carbonate (Pb3(OH)2. (CO3)2 or white lead
used as a paint base. Tetraethyl lead (Pb(C2H5)4 or TEL
colorless liquid used as an antiknock additive in aviation of gasoline.