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Chemistry!! > 6 Metallurgy > Flashcards

6 Metallurgy Flashcards

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1
Q

Basis of differentiation for Metals and Non metals are?

A

Atomic Structure

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2
Q

What are physical differences depended on?

What are chemical differences depende on?

A
  1. Arrangement of Atoms
  2. a. Number of valence shell
    b. Their behaviour during chemical reaction (ability to redox)
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3
Q

Quality of the metals can be improved by?

A
  1. Alloying (mixing with other metals)

2. Protecting by electroplating

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4
Q

What is Metallurgy?

A

The large scale process of involved in extraction of pure metals from their respective ores.

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5
Q

Give the properties of metals and their exceptions for each.

A
  1. Exist in solid state: Mercury
  2. MP and BP: Na, K, Hg
  3. Density: Na, K, Ca
  4. Ductility: Hg, Zn
  5. Malleability: Zn
  6. Amphoteric oxides: ZAP
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6
Q

Give the properties of Non-metals and exception for each:

A
  1. Non Lustruous: Iodine and Graphite
  2. MP and BP: Carbon and Silicon
  3. Density: Diamond
  4. Ductility: Carbon Fibre
  5. Malleability: Carbon Fibre
  6. Acidic or Neutral oxides (CO, N2O, NO, H2O)
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7
Q

Occurance of metals can be:

A
  1. Free or Naitive

2. Combined

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8
Q

What is free or Native state?

A
  1. Occuring in freee metallic form
  2. Not acted upon by natural elements
  3. Like constituents of air and Water
  4. Example Gold and Platinum
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9
Q

What is Combined state?

A

Metals occuring in the form of Compounds.

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10
Q

What is a mineral?

A
  1. Compounds of various metals
  2. Found in nature
  3. Assosciated with their earthly impurities
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11
Q

What is an Ore?

A
  1. Naturally occuring mineral
  2. From which metals can be extracted
  3. Profitably and Conveniently
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12
Q

What is Metallurgy?

A
  1. Large scale process
  2. Involved in the extraction of pure metals
  3. From their respective ores
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13
Q

What is a matrix?

A
  1. Rocking impurities (including silica, mud)
  2. Assosciated with the ore
  3. Also called Gangue
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14
Q

What is a Flux?

A
  1. Substance added to the ore
  2. To get rid of matrix
  3. Resulting in the formation of a fusible compound -> SLAG
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15
Q

What are the steps involved in the extraction of Aluminium?

A
  1. Dressing of the ore (Concentration of the ore and seperating ore from Gangue) -> Baeyer’s Process.
  2. Conversion of Ore to Oxide Ore (not necesary)
  3. Reduction of metallic oxide to metal (Hall Heroult’s Process)
  4. Electrorefining -> Hoope’s Process
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16
Q

What is the most abundant metal in the earth’s crust? Give its %
Which is the 2nd most abundant metal in the earth’s crust? Give its %

A

Aluminium (7.4%)

Iron(4.7%)

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17
Q

Why doesnt aluminium occur in free state?

A

Because it is a reactive metal

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18
Q

What is the main ore of Aluminium?

What kind of oxide is it?

A

Bauxite (Al2O3.2H2O)

It is an amphoteric Oxide.

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19
Q

Give the three equation of Dressing of the ore.1

A
  1. Converting impure bauxite to Sodium Aluminate:
    Al2O3. 2H2O + 2NaOH —> (150 to 200*) NaAlO2 + 3H2O
  2. Converting Sodium Aluminate to Aluminium Hydroxide:
    NaAlO2 + 2H2O —> (50 to 60*) Al(OH)3 + NaOH
  3. Converting of Al(OH)3 to Pure Alumina:
    Al(OH)3 —->(1100*) Al2O3 + 3H2O
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20
Q

Give the points of first step of the first step in extraction of aluminium:

A
  1. Bauxite (amphoteric) reacted with conc. Soln. of NaOH (base)(FOR 2 HRS UNDER PRESSURE) —> Gives salt and water.
  2. Impurities dont react -> Not amphoteric
  3. Impurities are seperated out AS RESIDUE
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21
Q

What are the two main impuries assoscitated with the bauxite ore?

A
  1. Fe2O3 and SiO2
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22
Q

Give the points of fsecond step of the dressing in extraction of aluminium:

A
  1. NaAlO2 diluted with water + Crystals of Al(OH)3 —> Further precipitates Al(OH)3. This is called Seeding
  2. After Agitation insoluble Al(OH)3 is filtered out and dried.
    THIS IS HYDROLYSIS
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23
Q

Give the points of third step of the dressing in extraction of aluminium:

A
  1. Precipitated Al(OH)3 is ignited (1100) to give pure alumina.
24
Q

What is the second step in extraction of aluminium?

A

Concentrated ore to its oxide.

Not Necessary. Ore is already oxide.

25
Q

What is the 3rd step in extraction of Aluminium?

A

Hall Heroult’s Process.

Conversion of Pure Alumina to Pure Al

26
Q

Give the constituents and ratio of the electrolytes used?

A

Fused Alumina: Cryolite (Na3AlF6) : Fluoraspar (CaF2) :: 1: 3: 1
By weight

27
Q

What is the cathode and Anode of the electrolytic cell in hearoult’s process?

A

Cathode: Carbon Lining (gas carbon) of the cell
Anode: Carbon Rods (Graphites) attached to copper clamps dipping into fused electrolyte

28
Q

Temperature and Current needed for the electrolyte is?

A

950 degrees

100 amperes at 6 to 7 volts

29
Q

The electrons involved in the balanced equation is?

A

Six Electrons

6

30
Q

The products formed in anode and cathode are?

A

Cathode: Pure aluminium metal
Anode: Oxygen gas (CO and CO2)

31
Q

Why is Aluminium Electrolytically reduced?

A
  1. Al2O3 is highly stable oxide. =>
  2. Aluminium has strong affinity for oxygen.
  3. Hence cant be reduced by reducing agents.
32
Q

What are the difficulties faced during the electrolytic reduction of aluminium?

A
  1. High temperatures due to the MP (2050) of Alumina
    a. Large amount of electrical energy required to liberate Al from Alumina.
    b. Large amount of electrical energy to Mantain the electrolyte in the molten state.
    c. Liberated Al (650) will volatize out and wasted.
  2. Fused alumina is almost a non-electrolyte
33
Q

What is the MP of alumina and Aluminium?

A

Alumina -> 2050 degrees

Aluminium -> 660 degrees

34
Q

Why is Cryolite and Fluorspar added?

A

Addition of Cryolite (mainly in a higher ratio) and Fluorospar:
1. Lowers the Fusion point to 950 instead of 2050.
2. Enhanced the mobility by acting as a solvent for electrolytic mixture.
Cryolite:
1. Molten state of subdivision -> Dissolves Alumina
2. Enhances the conductivity of the mixture -> Pure alumina (non-conductor)

35
Q

What are the elements present in the electrolyte?

A

Al2O3, Na3AlF6, CaF2

36
Q

Who resolved the difficulties faced during the eelctrolytic reduction of copper and made it cheaper and Simpler and when?

A

Charles Hall in 1886.

37
Q

Why is a layer of coke sprinkled over the electrolytic mixture?

A
  1. Prevents buring of carbon electrolodes in air (at the emergence point of the bath)
  2. Prevents heat loss by radiaiton
38
Q

Why are graphite anodes continuously replaced?

A
  1. Oxygen is evolved
    a. May escape as agas
    b. React with carbon anode.
    i. Oxidies to Carbon monoxide can escape through an outlet or
    ii. Can further burn to CO2
  2. Carbon is consumed and renewed perioidcally.
39
Q

why is it preferable to use a number of graphite electrodes as anode instead of single electrode?

A

This is because carbon anode is consumed after a certain period of usage.

40
Q

Pure aluminium is ___ than the electrolyte.

It is periodically removed through the ___ or ___ at the ___

A

Heavier

Outlet or Tap hole at the base

41
Q

Decrease in concentration of Al2O3, ___ the resistance and ___ on the control lamp.

A

Increases, GLOW

Unintuitive

42
Q

Why is electrolytic reduction of aluminium said to be a continuous process?

A
  1. Pure aluminium settles down (heavier). Periodically removed thu outlet and tap hole at the base.
  2. When concentration falls (resistance increases and light bulb glows) then more alumina is added.
    Then the process continues.
43
Q

Al that is obtained is almost ___% pure

A

99.5% !!!

44
Q

What is the step 4 of extraction of aluminium?

A

Electrorefining of the impure metal (already 99.5% pure -_-)

45
Q

Tank contains, how many layers and what are they>O

In Hoope’s process

A 
Upper Layer (Cathode), Molten Pure Al with carbon Electrodes
Middle layer (electrolyte) -> Cryolite, CaF2, BaF2, AlF (*NOT AlF3*)
Lower Layer (Anode) -> Impure Al with carbon lining at the anode.
46
Q

How is Pure Al withdrawn in Hoope’s Process?

A

Tapping Hole

47
Q

What are Alloys?

A
  1. Substance prepared by adding other metals (or non-metals)
  2. To a base metal
  3. In appropriate proportions
  4. Obtain certain desirable properties.
48
Q

How are alloys made?

A

By melting components TOGETHER and solidifying the mixture.

49
Q

Properties of Alloys:

A
  1. Its components must be miscible and not seperate on solidification
  2. Properties are intermediate between those of the metals composing them.
50
Q

What is Amalgam?

A

An alloy in which base metal is mercuy.

51
Q

What is Liquid amalgam and an amalgam used in voltain cells?

A
  1. Na/Hg

2. Zn/Hg

52
Q

What are the ores of alluminium?

A
  1. Duralumin

2. Magnalium

53
Q

Give the percentage composition and materials involved in Duralumin.

A

Al (95%)
Cu (4%)
Mg (0.5%)
Mn (0.5%)

54
Q

Give the percentage composition of Magnalium?

A
  1. Al (95%)

2. Mg (5%)

55
Q

Uses of the Al Alloys:

A

Duralumin -> Al (lightness) and Mg (Strength)
Aircrafts, Light tools and Cooker
Magnalium -> Light, Hard, Tough and Corrosion resistant
Aircrafts, Scientific tools

Chemistry!! (6 decks)

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