Metallurgygy

Introduction to Metallurgy

Metallurgy deals with extractiond ifi ti f t l fand purification of metals from

their sources. Very few metalstheir sources. Very few metalslike gold, silver etc. occur innative state, while most othermetals occur as their compoundsmetals occur as their compounds.

More electropositive metalslik th lk li d lk li thlike the alkali and alkali earthmetals occur as their halidesmetals occur as their halidesand nitrates while less basicmetals such as copper,i t f d th izinc etc., are found as their

oxides and sulphidesoxides and sulphides.

Extraction of the metal from its t act o o t e eta o tssources revolves around the following steps:

Concentration of the oreConcentration of the oreExtraction of the crude metalPurification of the crude metal

Types of MetallurgyTypes of Metallurgy

P t ll i lPyrometallurgy involvesextraction of the metal fromit i th lt t tits sources in the molten state.Electrometallurgy involves l t l i f th ltelectrolysis of the molten

metal halide.H d t ll lHydrometallurgy employs a complexing reagent like a

id t di l t th t lcyanide to dissolve out the metal.

Minerals and OresA mineral is mined out fromthe bowels of earth andthe bowels of earth andcontains larger amounts ofggangue, while ore is rich in metal

t t G i t dcontent. Gangue associatedwith the ore is usually silica.y

During the extraction of the

metal from its ore, gangue is

d f ibl l bremoved as fusible slag by

freaction with a flux.

A flux combines with the

gangue to form a slag and

sometimes helps in lowering

th lti i t f ththe melting point of the ore.

Purification of thecrude metal

Liquation is used to purify lowLiquation is used to purify low melting metals such as lead and tin.Electro refining is used to get pure metals During this process crudemetals. During this process, crude metal is made the anode and a thin foil of the pure metal is connected to the cathodethe cathode.

The electrodes are dipped in a solution of the metal salt andsolution of the metal salt and electrolysed when pure metal is deposited on the cathode Anodicdeposited on the cathode. Anodic mud obtained during theprocess is processed to getprocess is processed to getother metals present.Zone refining is a specific method to get ultra pure zirconium and silicon.get ultra pure zirconium and silicon.

Nernst Distribution law

At constant temperature, asolute distributes itself between two immiscible solvents such thattwo immiscible solvents such thatthe ratio of its concentration inthe two solvents is a constant.

Parke’s process: Molten argentiferous lead is treatedargentiferous lead is treatedwith molten zinc when silver present in the lead dissolvesin zinc and is removed assilver zinc alloy From thissilver-zinc alloy. From this,the silver is recovered.

Ellingham diagramsg g

These are graphs in which standard g p

free energies of formation of oxides,

sulphides etc., of metals are plotted

versus increasing temperatures.

E ti ∆G0 ∆H0 T∆S0Equation: ∆G0 = ∆H0 - T∆S0

As temperature increases ∆G0As temperature increases, ∆G

also increases and hence

oxides are unstable at high

temperatures.

CO is a better reducing agent forCO is a better reducing agent for

Haematite below 7000 C and Coke

reduces better beyond 9000 C.

Oxides of Chromium and Manganese

are reduced by Aluminium.

Metallurgy of Iron

Powdered concentrated

haematite is calcined. It is

mixed with lime stone and

coke in the ratio of 8:1:4.

The charge is fed into blast g

furnace where hot air is blown

up. Coke burns to give CO2 and

the reaction being exothermic

moves CO2 upwards.

CO2 is reduced to CO by carbon.

CO2 + C 2CO

At the top of the furnace, CO

reduces Fe2O3 to iron.

Fe2O3 + 3CO 2Fe + 3 CO2

Industrially Important Compounds

Manufactures of Caustic Soda,

Ammonia, Sulphuric Acid and

Potassium di chromate.

d-block ElementsThe d-block elements are those elements whose atoms or ionselements whose atoms or ionsin the ground state havepartially filled d-sub shell.

General configuration [Noble gas] (n-1) d1-10ns1-2.( )

These elements show variable oxidation statesvariable oxidation states,magnetic behavior, formg ,colored compounds andstable co-ordination compounds. They are also good industrialThey are also good industrial catalysts.

Questions

1) Which of the following1) Which of the followingstatements is false?a) The ore is free from almost alla) The ore is free from almost all non-metallic impurities.b) During roasting moisture isb) During roasting, moisture is removed from the ore.c) Concentrated inc blend isc) Concentrated zinc blend is subjected to calcination during extractionextraction.d) Calcination is carried out in absence of airabsence of air.

Answer:

) C t t d i bl dc) Concentrated zinc blend

is subjected to calcinationis subjected to calcination

during extractionduring extraction.

2) In chromite ore, oxidationb f i d h inumber of iron and chromium

are respectively:are respectively:a) +3, +6.b) +3, +2

) +2 +3c) +2, +3d) +2, +6d) 2, 6

Answer

c) +2 +3c) +2, +3

3) The yellow precipitate formed during the chromyl chlorideduring the chromyl chloridetest is chemically _______.

a) lead chromateb) h i idb) chromic acidc) sodium chromatec) sodium chromated) lead acetate

Answer

a) lead chromate)

4) 1 gram of silver gets distributed ) g gbetween 10 cc of molten zinc

fand 100 cc of molten lead at8000 C The percentage of silver800 C. The percentage of silver still left in the lead layer is

i t lapproximately _____.a) 5 c) 1a) 5 c) 1b) 2 d) 3

AnswerAnswer

d) 3d) 3

5) Of the following transition5) Of the following transitionmetals, the maximumnumbers of oxidation statesare exhibited by_____a) Manganese (Z=25)a) Manganese (Z=25)b) Iron (Z=26)c) Titanium (Z=22)d) Chromium (Z=24)

Answer:

a) Manganese (Z=25)a) Manganese (Z=25)

6) The spin only value ofmagnetic moment ofmagnetic moment ofMn+4 ion is nearly _____y _____a) 4 B.Mb) 5 B.Mc) 3 B Mc) 3 B.Md) 6 B.M)

Answer:

a) 4 B Ma) 4 B.M

7) Carbon can reduce ferric oxide7) Carbon can reduce ferric oxideto iron above 983 K because:

) f h f tha) free energy change for the formation of CO2 is less negative th th t f f i idthan that for ferric oxide

b) iron has a higher affinity towards oxygen than carbon

c) CO formed is thermodynamically ) y yless stable than ferric oxide

d) carbon has higher affinity towardsd) carbon has higher affinity towards oxidation than iron

Answer:Answer:

d) carbon has higherd) carbon has higher

affinity towardsaffinity towards

oxidation than ironoxidation than iron

8) Th th t i t t d8) The ore that is concentrated

b f th fl t ti iby froth floatation is_____.

a) bauxitea) bauxite

b) malachiteb) malachite

c) zincitec) zincite

d) cinnabard) cinnabar

Answer:

d) cinnabar)

9) The order of stability ofmetal oxides ismetal oxides isa) Fe2O3 < Cr2O3 < Al2O3 < MgO) 2 3 2 3 2 3 gb) Fe2O3 < Al2O3 < Cr2O3 < MgOc) Al2O3 < MgO < Fe2O3 < Cr2O3

d) C O < M O < Al O < F Od) Cr2O3< MgO < Al2O3 < Fe2O3

Answer:

d) Cr2O3< MgO < Al2O3 < Fe2O3) 2 3 g 2 3 2 3

10) The temperature of the) pslag zone in the metallurgyof iron using blastfurnace isfurnace is_______.a) 400 – 7000 Cb) 800 – 10000 C

) 1200 15000 Cc) 1200 – 15000 Cd) 1500 – 16000 C)

Answer:

b) 800 – 10000 C)

11) The function of Fe(OH)3

in contact process is:

) t i ta) to remove moisture

b) t d t ti lb) to remove dust particles

c) to remove arsenic impuritiesc) to remove arsenic impurities

d) to detect colloidal impuritiesd) to detect colloidal impurities

Answer:

c) to remove arsenic impuritiesc) to remove arsenic impurities

12) Th i t t t t12) The incorrect statement with respect to Chromylwith respect to Chromylchloride test isa) formation of Chromyl chloride b) liberation of chlorineb) liberation of chlorinec) formation of red vapoursd) formation of lead chromate

Answer:

b) liberation of chlorineb) liberation of chlorine

13) Which of the followingions has maximum numberions has maximum numberof unpaired electrons? pa) Mg2+

b) Ti3+

c) V3+c) Vd) Fe2+

Answer:

c) V3+c) V3+

14) The highest magnetic14) The highest magneticmoment is shown by theytransition metal ion

ith th fi tiwith the configuration: a) 3d5a) 3db) 3d2

c) 3d9

d) 3d7d) 3d7

Answer:

a) 3d5a) 3d

15) Which of the followingions has maximum numberions has maximum number

of unpaired electrons? a) Mg2+

b) Ti3+b) Ti3+

c) V3+c) Vd) Fe2+

Answer:

) V3+c) V3+

16) Wh lt h t d16) When a salt was heatedwith concentrated H2SO4 a t co ce t ated 2SO4, areddish brown gas is evolvedand a red solution is obtained. The salt may be:The salt may be:a) Chloride c) Iodideb) Bromide d) Nitrate

Answer:Answer:

b) B idb) Bromide

17) ∆G0 V T l t i Elli h17) ∆G0 Vs T plot in Ellingham diagram slopes downwarddiagram slopes downwardfor the reaction:a) 2Ag+½O2 Ag2Ob) Mg+½O MgOb) Mg+½O2 MgOc) CO+½O2 CO2) 2 2

d) C +½O2 CO

Answer:

d) C +½O2 COd) C ½O2 CO

18) Which of the followingreactions taking place in thereactions taking place in the blast furnace is endothermic? a) 2C+O2 2COb) C CO C O COb) CaCO3 CaO+CO2

c) Fe2O3+3CO 2Fe+3CO2) 2 3 2

d) C+O2 CO2

Answer:Answer:

a) 2C+O 2COa) 2C+O2 2CO

19) Which of the following

is not affected by

concentrated H2SO4?

a) H2S b) HI

) HB d) HClc) HBr d) HCl

Answer:

d) HCld) HCl

20) In the manufacture ofammonia by Haber’s process, N +3H < 2NH ∆H 92 3 kJN2+3H2< 2NH3; ∆H= - 92.3 kJ. Which of the followinggconditions is unfavorable?

) R i i it i f da) Removing ammonia as it is formedb) Increasing temperature) g pc) Increasing pressured) Reducing temperature

Answer:

b) Increasing ) gtemperature

21 When compared to ∆G021. When compared to ∆G0 for the formation of

0Al2O3, ∆G0 the formation of Cr2O3 is 2 3a) Higherb) Lowerb) Lower c) Samed) C t bd) Cannot be

predicted

Answer:

a) Highera) Higher

22. Which one of the following pairs of ionsfollowing pairs of ionshave the same of electronic configurationconfiguration

a) Ni2+, Co3a) Ni2 , Co3b) Fe2+ , Mn2+c) Fe3+ Mn2+c) Fe3+, Mn2+d) Sc3+, Ti3+

Answer:

c) Fe3+ Mn2+c) Fe3+, Mn2+

23. Which of the following does not have valance electron in 3d sub shell

a) Fe (III)

b) M (II)b) Mn (II)

c) Cr (I)c) Cr (I)

d) P(o) d) (o)

Answer:

d) P(o)d) P(o)

24. [ Ti(H2O6)]3+ is purple in24. [ Ti(H2O6)] is purple in colour because is

li tcomplimentarycolour of a) Greenish Yellow

b) Red

) Gc) Green

d) Blued) Blue

Answer:

a) Greenish Yellow

25 Of th f ll i t25. Of the following outer electronic configuration of the atoms the highest oxidation state is exhibitedoxidation state is exhibitedby which one of them?

a) (n-1) d8ns2 b) (n-1) d5ns1

c) (n-1) d3ns2 d) (n-1) d5 ns2

Answer:Answer:

d) (n-1) d5 ns2d) (n-1) d5 ns2

26. Which one of the following metal ionsfollowing metal ionsis coloured

) C +a) Cu+

b) Zn2+b) Zn2

c) Sc3+ c) Sc

d) V4+

Answer:

d) V4+

27. Which one of the

following shows

hi h t ti thighest magnetic moment

) V3 b) C 3a) V3+ b) Cr3+

c) Fe3+ d) Co3+c) Fe3+ d) Co3+

Answer:

c) Fe3+

28 Th f ti f i28. The function of ironpowder in Haber’smethod for the manufacture of NH3 is to3a) Increase the yield of NH3b) Establish the equilibriumb) Establish the equilibrium

earlierc) Proceed the reaction underc) Proceed the reaction under

low pressured) act as promoterd) act as promoter

Answer:

b) Establish theb) Establish the equilibrium earlier

Q29. A mixture of ammoniumQ29. A mixture of ammonium nitrate and aluminum powder is used aspowder is used as explosive under the name

a) Amatol b) Amonal

c) Blasting TNT d) RDX

Answer:Answer:

b)Amonal

30 The catalyst used in30. The catalyst used in Haber’s process is

l bd Thmolybdenum. The function of Mo is to a) increase the rate of

combination of gasesgb) remove the impurities

present in the gasesc) increase the activity of

the catalystd) t bli h th E ilib id) establish the Equilibrium

Answer:

c) increase the activityof the catalyst

31. Oleum is

a) castor oil

b) oil of vitriol

c) H2SO4

d) H2S2O7

Answer:

d) H S Od) H2S2O7

32. Concentrated 32. Concentrated Sulphuric acid acts asSulphuric acid acts asSulphuric acid acts as Sulphuric acid acts as

a) Oxidizing agenta) Oxidizing agent

b) Dehydrating agentb) Dehydrating agent

c) Both

d) Reducing nature

Answer:

c) BothBothc) BothBoth

33. When hydrogen peroxide istreated with cold acidifiedt eated t co d ac d edK2Cr2O7 solution containingether a blue colour is obtained this is due to

a) Chromi m s lphatea) Chromium sulphateb) Potassium chromatec) Perchromic acidd) Chromium pentoxided) Chromium pentoxide

Answer:

d) Ch i t idd) Chromium pentoxide

34. NaOH is manufactured by electrolysis of brine theelectrolysis of brine, the products of the reaction are a) Cl2 and H2

b) Cl2 and Na

) Cl d di lc) Cl2 and sodium amalgam

d) Cl2 and O2d) Cl2 and O2

Answer:Answer:

a) Cl2 and H2

35. The structure of ammonia molecule is

a) Pyramidal

b) Triangularb) Triangular

c) Square planarc) Square planar

d) Linear )

Answer:

) P id la) Pyramidal

36. When oxalic acid is d h d t d b t t ddehydrated by concentratedH2SO4 then it forms 2 4

a) C+CO2b) COb) COc) CO2d) CO+CO2

Answer:Answer:

d)d)CO+CO2CO+CO2d)d)CO+CO2CO+CO2

37. Liquid ammonia is used in refrigeration becausein refrigeration becauseof its

a) High degree of vaporization

b) B i itb) Basicity

c) Square planerc) Square planer

d) Linear)

Answer:

a) High degree of) g gvaporization

38. Potassium chromate is38. Potassium chromate is converted into potassium dichromate by addingdichromate by adding a) KOH)b) Sulphuric acidc) acetic acidc) acetic acid d) ammonium hydroxide

Answer:

b) S l h i idb) Sulphuric acid

39. Which one of the f ll i t itifollowing transition metal has lowest density

a) Copper b) Ni k lb) Nickel c) Scandiumd) Zinc

Answer:

) S dic) Scandium

40. Oxidation state of

osmium (OS) in OSO4 is

a) +4 b) +6) )

c) +7 d) +8

Answer:Answer:

d) +8

41 The catalytic activity of41. The catalytic activity of the transition metals andth i d i d ttheir compounds is due to a) The chemical reactivityb) f i db) presence of unpaired

electronc) Their unfilled d orbitalsc) Their unfilled d-orbitalsd) Their ability to adopt

multiple oxidation statesmultiple oxidation states and availability of adsorption sitess tes

Answer:

d) Th i bilit t d td) Their ability to adopt multiple oxidationmultiple oxidationstates and availability of adsorption sites

42. Cu+ ion exists rarely in Cu o e sts a e yaqueous solution due to

a) oxidation

b) reduction

c) Disproportinationc) Disproportination

d) Instabilityd) Instability

Answer:Answer:

)) id tiid tia)a) oxidationoxidation

43 Which orbit is present as43. Which orbit is present as eg orbital

a) dxy b) dx2 – y2

c) dyz d) dxz

Answer:Answer:

b) dx2

– y2

44. Which of the following pairs of elementspairs of elements cannot form an alloy

a) Zn, Cu

b) Fe, C

) F Hc) Fe, Hg

d) Hg Nad) Hg, Na

Answer:

c) Fe Hgc) Fe, Hg