Misc

Question 1

Corrosion in steel and aluminium

Answer 1

Iron oxide is porous so allows diffusion of oxygen and water through

Aluminium is more reactive than iron, it forms a stable and thin layer of oxide that sticks to it. It’s impermeable to air, water and ions

Question 2

Different types of adherence

Answer 2

VDWs
Chemical bonding
Mechanical interlocking
Capillary interaction
Suction
Diffusion
Electrostatic forces
Magnetism

Question 3

Adhesive bonding uses?

Answer 3

Mechanical interlocking
Diffusion
Chemical
Electrostatic

Question 4

Requirements for a good adhesive

Answer 4

Viscosity
Similar surface energies
Forms strong bonds

Question 5

Types of adhesives

Answer 5

Two part
Heat curing
Moisture curing 
Solvent based
Hot melt 
Pressure sensitive

Question 6

Wood cells

Answer 6

Support and storage

Question 7

Composition of wood

Answer 7

50% Cellulose- provides the strength
20% Hemicellulose- bonds cellulose together
20% Lignin- glues cells together
10 % Extractives

Question 8

Why are metals ductile while ionic compounds brittle?

Answer 8

Metal bonding is less directional and is stable as long as atoms stay together.
Deformation can occur with less chance of cracking

Ionic compounds have quite directional bonds between + and - ions
When deformed like charges come together, this is v. Unstable and leads to cracking

Question 9

Temperature of a Blast Furnace?

Answer 9

1900 C to 200 C

Question 10

Reactions in blast furnace

Answer 10

Fe2O3 + 3CO ->2Fe+3CO2
CaCO3-> CaO+CO2
CaO+SiO2-> CaSiO3
CO2+C-> 2CO
C+O2-> CO2

Question 11

Temperature in an Electrylitic Cell

Answer 11

950C

Question 12

Ampage and Voltage of modern Cells?

Answer 12

150K-350K amps

4-4.5 Volts