metallurgy

Question 1

Bauxite

Answer 1

Principal Ore of aluminium
AlO_x(OH)_3-2x
0<x<1

Question 2

Kaolinite

Answer 2

[Al₂(OH)₄Si₂O₅]
Ore of aluminium

form of clay

Question 3

Haematite

Answer 3

Iron ore
Fe₂O₃

Question 4

Magnetite

Answer 4

Iron ore
Fe₃O₄

Question 5

Siderite

Answer 5

Iron ore
FeCO₃

Question 6

Iron pyrites

Answer 6

Iron ore
FeS₂

Question 7

Sphalerite

Answer 7

Zinc blende
ZnS

Question 8

Calamine

Answer 8

Zinc ore
ZnCO₃

Question 9

Zincite

Answer 9

ZnO
Zinc ore

Question 10

Copper pyrite

Answer 10

copper ore
CuFeS₂

Question 11

Malachite

Answer 11

copper ore
CuCO₃.Cu(OH)₂

Question 12

Cuprite

Answer 12

copper ore
Cu₂O

Question 13

Copper glance

Answer 13

copper ore
Cu₂S

Question 14

Gemstones are impurities of which compound?

Answer 14

Al₂O₃

Question 15

What is the impurity in ruby

Answer 15

Cr

Question 16

What is the impurity in sapphire

Answer 16

Co

Question 17

What is concentration of ore?

Answer 17

Removal of impurity
Also called dressing or benefaction

Question 18

Hydraulic washing

Answer 18

Concentration of ore based on difference in densities of gangue and ore

Question 19

Which type of ore is froth floatation method used for

Answer 19

Sulphide ores

Question 20

Function of collectors in froth floatation method

Answer 20

Enhances non-wettability of mineral particles

Question 21

Name collectors used in froth floatation method

Answer 21

pine oils, fatty acids, xanthates

Question 22

Name froth stabilisers

Answer 22

Cresol, aniline

Question 24

What do we do when there are two sulphides present in the same ore? Give example

Answer 24

Depressants to separate sulphides
E.g. NaCN, prevents ZnS from coming to froth but allows PbS

Question 25

Impurities present in bauxite

Answer 25

SiO₂, iron oxides, TiO₂ ## Footnote do leaching rxn from pg 154 ncert part 1 class 12 Al₂O₃ + NaOH + H₂O --> Na[Al(OH)₄] prod^ + CO2 --> Al₂O₃ . xH₂O dehydration of^

Question 26

In extraction of gold, silver etc., what is used + what is added extra

Answer 26

NaCN, KCN O₂/air added extra

Question 27

Formula of complex formed in extraction of gold silver with NaCN/KCN and subsequently what is the compound reacted with?

Answer 27

[M(CN)₂]^- _(aq.) reaction with Zn because it will form [Zn(CN)₄]^2-

Question 28

Method of extraction of crude metal from concentrated ore

Answer 28

1. conversion to oxide by calcination/roasting 2. reduction of oxide to metal

Question 29

Calcination

Answer 29

Just heating pg 155 ncert class xii part 1

Question 30

Roasting

Answer 30

Rxn in the presence of oxygen ncert class xii part 1 pg 156

Question 31

Ellingham diagram

Answer 31

* Graph below will reduce graph above * Gibbs free energy on y axis, temperature on x axis

Question 32

Extraction of iron takes place in what?

Answer 32

blast furnace do rxns next to diagram pg 160

Question 33

Pig iron

Answer 33

Iron obtained from blast furnace, containing 4% carbon and impurities like S, P, Si, Mn

Question 34

Cast iron

Answer 34

Made by melting pig iron with scrap iron and coke using hot air blast slightly less carbon content

Question 35

Purest form of commercial iron

Answer 35

Wrought iron/malleable iron Prepared from cast iron by oxidising impurities in reverberatory furnace lined with haematite Fe₂O₃ + 3C --> 2Fe + 3CO

Question 36

How are oxides obtained from sulphide ores of copper

Answer 36

By roasting/smelting 2Cu₂S + 3O₂ --> 2Cu₂O + 2SO₂ Cu₂O + C --> 2Cu + CO

Question 37

Copper extraction in which furnace + what happens

Answer 37

ore is heated in reverberatory furnace after mixing with silica In the furnace iron oxide is converted to slag (iron silicate) FeO + SiO₂ --> FeSiO₃ Copper is produced in the form of copper matte which contains Cu₂S and Fe₂S

Question 38

What is done to copper matte

Answer 38

Charged into silica lined converter. Some silica is also added and hot aire blast is blown to convert remaining FeS, FeO, and Cu₂S/Cu₂O Blister copper is obtained at the end of the process. Blistered due to SO₂ ## Footnote rxns pg 162

Question 39

what is Al₂O₃ mixed with

Answer 39

Na₃AlF₆ or CaF₂ because they lower the melting point of the mixture and bring conductivity

Question 40

Hall-Heroult process ( aluminium ) cathode anode and rxn

Answer 40

cathode: steel vessel with lining of carbon anode: graphite 2Al₂O₃ + 3C --> 4Al + 3CO₂

Question 41

how is copper extracted from low grade ores and scraps

Answer 41

by hydrometallurgy leached out using acid or bacteria Solution containing Cu²⁺ is trated w scrap iron or H₂ Cu²⁺ (aq) + H₂ (g) --> Cu (s) + 2H⁺ (aq)

Question 42

refining methods

Answer 42

1. distillation 2. liquation 3. electrolysis 4. zone refining 5. vapour phase refining 6. chromatographic methods

Question 43

Liquation

Answer 43

Low melting metal like tin can be made to flow on a sloping surface

Question 43

distillation

Answer 43

low B.P. metals like Zn Hg

Question 44

electrolytic refining: impurities in anode mud

Answer 44

antimony, selenium, tellurium, silver, gold, and platinum

Question 45

zone refining

Answer 45

because impurities are more soluble in the melt than in the solid state of the metal semiconductor materials like germanium silicon boron gallium indium

Question 46

mond process for refining nickel

Answer 46

vapour phase refining nickel is heated in a stream of carbon monoxide forming a volatile complex Ni(CO)₄ the complex is decomposed at higher temp to obtain pure metal ## Footnote pg 165

Question 47

van arkel method for refining zirconium or titanium

Answer 47

Zr + 2I₂ --> ZrI ₄ ZrI₄ --> Zr + 2I₂

Question 48

metal used to galvanise iron

Answer 48

Zn

Question 49

Brass is an alloy of?

Answer 49

Cu and Zn

Question 50

German silver is an alloy of?

Answer 50

Cu, Zn, Ni