Definitions

Question 1

Blast Furnace Process

Answer 1

Blast furnace = steel structure lined with firebricks.
Ore + coke + limestone are charged into furnace.
Coke = fuel.
Chemical reaction reduces iron oxide to iron.
Blast of hot air blown through nozzles to increase quantity of iron.
Limestone = flux (takes no part in reaction - absorbs bulk of impurities and forms slag).
Iron + slag fall to bottom of furnace and are tapped from different ports.

Question 2

Extraction + Production of Aluminium

Answer 2

Extracted from BAUXITE.
Alumina first purified.
Then dissolved in molten cryolite.
Product is electrolysed to produce aluminium.

Question 3

Polymer Synthesis

Answer 3

Plastics derived from petrochemicals.

x2 Methods for forming large monomers = addition polymerisation + condensation polymerisation.

Question 4

Addition Polymerisation

PE, PP, PS, PVC, PTFE

Answer 4

Monomers join together.
No loss of atoms from molecules.
SPECIFIC polymer chain lengths produced.

Question 5

Condensation Polymerisation

PA, UP, PU

Answer 5

Monomers join together.
Elimination of atoms or group of atoms.
Variety of chain lengths produced.

Question 6

Ionic Bonding

Answer 6

Pair of elements. One with a loose electron, one with an electron gap.
Ions bond together due to attraction of opposite charges.

Question 7

Covalent bonding

Answer 7

Bonding based on sharing of electrons between atoms.
Strong.
Lack of free mobile electrons.
Poor conductors of heat and electricity.

Question 8

Van der Waals Bonding

Answer 8

Secondary bonding.
Molecules that are neutral or have no charge.
Molecules = dielectric diopoles.
Charges in molecules unevenly distributed.

Question 9

Hydrogen Bonding

Answer 9

Intermolecular.

Permanent diopole attraction.

Question 10

Metallic Bonding

Answer 10

Free roaming electrons shared by positive ions.

High electrical conductivity.

Question 11

Amorphous

Answer 11

Materials in which atoms and molecules are not arranged in any order.

Question 12

Crystalline

Answer 12

Materials that have atoms and molecules arranged in a specific order.

Question 13

Body Centre Cubic (BCC)

Answer 13

Chromium
Molybdenum
Tungsten
Iron

R=(a✔️3)/4
Volume of atoms=24/3(pir^3)
Volume of lattice cell = a^3

Question 14

Face-centred Cubic (FCC)

Answer 14

Aluminium 
Copper
Lead
Nickel
Gold

R=(a✔️2)/4
V=44/3(pir^3)
Volume of lattice cell = a^3

Question 15

Hexagonal-close-packed

Answer 15

Beryllium
Magnesium
Zinc
Titanium

Question 16

Packing Factor

Answer 16

Volume of atoms/Volume of lattice cell

Question 17

Point Defects

Answer 17

Vacancies = atoms missing at lattice points. 
Interstices = surplus atoms lodge into spaces.

Question 18

Line Defects

Answer 18

Extra plane of atoms within a crystal structure.
Originate during crystallisation.
When shears stress applied, stress builds up until bond breaks and dislocation moves.

Question 19

Planar Defects

Answer 19

Surface = defect because of different bonding to bulk of material.

Stacking faults = occur when stacking of atoms is disrupted.

Grain boundaries: Molten metal solidifies, crystals form. Each crystal = atoms aligned. When atoms touch boundaries are formed.

Question 20

Extraction of Iron

Answer 20

Main ores = haematite, magnetite, limonite.

Iron extracted using smelting in blast furnace, Bessemer process, open heart process and electric arc furnace process.

Question 21

Screw Dislocation

Answer 21

Slip direction = parallel to defect line.

Question 22

Volume defects

Answer 22

Defects that occupy a volume.

Question 23

Branched Polymers

Answer 23

Have side chains attached to chain molecule.

Branching cause by impurities of presence of monomers with reactive groups.

Question 24

Cross-linked polymers

Answer 24

Two or more chains joined together by side chains.
Cause by chemical reactions.
Eg. Vulcanised rubber, thermosetting plastics.

Question 25

Thermoplastics

Answer 25

Van der Waals force.
Amorphous or semi crystalline.
Flexible - molecular rotation.
More crystallinity = greater stiffness.

Question 26

Amorphous Thermoplastics

ABS, PMMA, PC, PS, PVC

Answer 26

Lower shrinkage
Good surface finish
Easier to deform

Inferior resistance

Question 27

Semi Crystalline Thermoplastics

PA, PE, PP, PET

Answer 27

Better chemical resistance
Good wear resistance

Higher creep
More variable shrinkage

Question 28

Thermosets

Epoxy Resins, MF, UF

Answer 28

Cross linked molecular structures using covalent bonds.

Weaker at high temps.

Question 29

Thermal transitions

Answer 29

Tm = melting point

Tg= glass transition temp. (Temp. at which polymer chains can vibrate)

Question 30

Solid solution

Answer 30

Solid solution formed when solute added to solvent without having changing the crystal lattice.
No new structure formed.

Question 31

Constitution (alloy)

Answer 31

Phases present
Weight fraction of each phase
Composition of each phase

Question 32

Liquidus line

Answer 32

Line above which only liquid phase exists. Below the SOLIDUS line only the solid phase exists. SOLVUS line indicates limit of solid solubility in diagram.

Question 33

Eutectic

Answer 33

An isothermal reaction in which one LIQUID phase freezes to form two or more SOLID phases.

Question 34

Eutectoid

Answer 34

One SOLID solution changes into TWO OTHER SOLID PHASES.

Question 35

Strain/work hardening

Answer 35

Strengthening of material so that higher stresses are required to deform it plastically.
Occurs due to crossing of paths of gliding dislocations. Gliding dislocations meeting grain boundaries = prevent motion.

Question 36

Precipitation/age hardening

Answer 36

Improves strength by introduction of small particles.
Used in alloys.
Alloy heated to temp where second phase is completely soluble. Alloy rapidly quenched.