Metallurgy

Question 1

What is metallurgy ?

Answer 1

Extracting metal from their ores

Question 2

Difference between metals and non metals ?

Answer 2

A] Lose electron - metals - to form cation - oxidation , gains electron - non metal - to form anion - reduction
b] metals - electron donor , non metals -electron accepter
C] cations - metals , anions - non metals
d] electrovalent compound - metals , covalent compound or electrovalent compound - non metals
e] Metals - Good reducing agent , nonmetals - good oxidising agent

Question 3

Properties of metals -

Answer 3

Lustrous , malleable , conductivity - Good conductor , density- high , ductility- high ,melting and boiling point - high

Question 4

Exception for properties of metals -

Answer 4

Melting and boiling point - Na ,K, Hg
Density - Na , K , Ca
Ductility - can be drawn into wires - Exception - Zn , Hg
Malleability - Can be beaten into sheets - Exception -Zn

Question 5

Oxide Compounds [metals]-

Answer 5

Bauxite - [Al2O3.2H2O]
Zincite- [ZnO]
Haematite-[Fe2O3]
Cuprite-[Cu2O]

Question 6

Carbonates [Metals] Compounds -

Answer 6

Siderite - FeCO3
Marble - CaCO3
Calamine - ZnCO3
Magnesite -MgCO3

Question 7

Metals Halides Compounds-

Answer 7

Cryolite - Na3 AlF6
Rock salt - NaCl
Horn silver - AgCl
Fluorspar - CaF2

Question 8

Metals Compounds Sulphides -

Answer 8

Iron pyrite - FeS2
Zinc Blende-ZnS
Galena - PbS
Cinnabar -HgS

Question 9

Metals Sulphates compound -

Answer 9

Gypsum - CaSO4.2H2O
Baryte -BaSO4
Epsom salt - MGSO4.7H2O
Anglesite - PbSO4

Question 10

What is mineral ?

what is ore ?

Answer 10

• The compounds of various metals found in nature - associated with their earthly impurities called minerals
• The naturally Occurring mineral from which metals can be extracted profitably and conveniently

Question 11

Matrix -

Flux-

Answer 11

Rocky impurities including silica [Sio2] , Mud etc

Substance added to ore to get rid of matrix - resulting in formation of fusible compound - slag

Question 12

Ores of aluminium -

Answer 12

Bauxite - Al2O3.2H2O -Main ore - Hydrated Aluminium oxide
Cryolite- Na3AlF6 - sodium aluminium fluoride
Corundum -Al2O3 - Aluminium oxide

Question 13

Ores of Zinc -

Answer 13

Zinc blende - ZnS
Calamine - ZnCO3
Zincite - ZnO

Question 14

Ores of Iron -

Answer 14

Haematite- Fe2O3 - Iron oxide
Magnetite- Fe3O4 - Tri iron tetra oxide
Iron pyrites -FeS2 - Iron disulphate
Spathic iron ore - FeCO3 - Iron 2 carbonate

Question 15

Extraction of Aluminium - STEP :1 
Ore used-
Method used - 
Process used -
Conversion -
Reaction -

Answer 15

Bauxite
Chemical method using conc.NaOH
Baeyer’s Process
Al2O3.2H2O –> AL2O3
1ST . IMPURE ORE + NAOH –> 150*C NAALO2 + H20
2ND . SALT ON HYDORLYSIS –> NAOH + AL[[OH]]3
3RD . INSOULUBLE HYDROXIDE –> AL2O3 + H2O

Question 16

Step 3  extraction of aluminium 
method
process
 conversion 
reaction
electrolyte
electrodes
]reaction

Answer 16

Electrolyte
Hall heroult process 
AL2O3 --> PURE AL
ELECTROLYTIC REDUCTION PF AL2O3
FUSED ALUMINIA , CRYOLITE , FLUORSPAR 
INERT GRAPHIDE CARBON ELECTRODES
CATHODE- PURE ALUMINIA 
ANODE - OXYGEN GAS --> CO CO2 EVOLVED DUE TO OXIDATION OF CARBON ANODE

Question 17

Seeding means :-

Answer 17

process of adding Al[{Oh]} 3 to further precipitate out AL[{oh}}3

Question 18

Write down the conversion of bauxite to pure alumina

Answer 18

Al2O3.2H2O + H2O –> NaAlO2 + 3H2O
NaALO2 + 2H2O –> AL[[OH]]3 + NAOH
AL[[OH]]3 IGNITE –> AL2O3 + 3H2O [VAP]

Question 19

Step -3 reduction of aluminium oxide to alumina -pure 
Electrolyte- 
electrolytic cell -
electrolytic reaction -
products formed -

Answer 19

Cryolite , fluorspar , fused alumina 
Cathode - carbon lining -gas carbon 
anode - Thick carbon rod - graphite --> attached to copper clamps dipping into fused electrolyte 
temp-950* , I - 100Ampere 
At cathode - 2Al +3 + 6e- --> 2Al
At anode - 3O2- - 6e- --> 3[O] --> 3O2

Question 20

why Al2O3 can’t be reduced to Al by reducing agent ?

Answer 20

Al2O3 is highly stable oxide - and has strong affinity for Oxygen
hence Al2O3 can be reduced to Al electrolytically .

Question 21

Difficulties faced during electrolytic reduction of Al2O3

Answer 21

Al2O3 has high melting point around 2050C - large amount of electrical energy is required and to maintain Al2O3 at molten state at that temp
liberated Al metal -660C may also tend to volatize out and get wasted

Question 22

Usage of Cryolite and fluorspar -

Answer 22

Addition of cryolite and fluorspar –> enhances the mobility of the fused mixture
addition of cryolite enhances the conductivity of the mixture
Al2O3 –> is a non conductor
the mixture fuses around 950c instead of 2050*c

Question 23

WHO REDUCED THE DIFFICULTY FACED DURING REDUCTION OF Al2O3 ?

Answer 23

CHARLES HALL IN 1886

Question 24

Why layer of powdered coke is used ?

Answer 24

Is sprinkled over the electrolytic mixture
1] prevents burning of carbon electrodes in air
2] minimizes or prevent the heat loss by radiation

Question 25

why graphite anode should be replaced periodically ?

Answer 25

Oxygen evolved at the anode escapes as gas or react with carbon anode carbon anode thus oxidised to carbon monoxide which either burns giving carbon dioxide or escapes out through an outlet hence carbon anode is consumed and renewed periodically preferable to use number of graphite electrode instead of single one

Question 26

what happens if concentration of Al2O3 falls ?

Answer 26

Resistance of the bath increases , indicated by glow of bulb

Question 27

Al can be further purified by

Answer 27

Hoope's process

Question 28

Alloys -

Answer 28

substance prepared by adding other metals or non metals - to a base metal in appropriate proportions - to obtain desirable properties

Question 29

which alloy has base metal mercury ?

Answer 29

amalgam

Question 30

Aluminium - Alloys-

Answer 30

Duralumin and magnalium Duralumin - 95% al , 0.5% - Mg Mn , Cu -4% magnalium - 95% AL , 5% MG duralumin - al imparts lightness , mg strength magnalium - light , hard , tough , corrosive resistant

Question 31

Duralumin and magnalium where they use this two metals

Answer 31

Duralumin --> aircrafts , light tools , cooker | magnalium --> Aircrafts , scientific tools