Topic 26 - Bulk and Surface Properties of Matter Including Nanoparticles

Question 1

9.35C - Compare the size of nanoparticles with atoms and molecules

Answer 1

10 times bigger than atoms and molecules.

Question 2

9.36C - Describe how nanoparticulates are related to their uses

Answer 2

Titanium dioxide can absorb ultraviolet rays in sunlight causing skin cancer.
Nanoparticulate titanium dioxide is used in sunscreens.

The large surface are to volume ratio is useful for catalysts.

Question 3

9.37C - Explain possible risks of nanoparticulate materials

Answer 3

Their small size means they can be breathed in and their large SA : V ratio may catalyse reactions or carry toxic substances.

Question 4

9.38C - Compare using data the physical properties of glass and clay ceramics, polymers, composites and metals

Answer 4

Ceramics are unreactive, hard and stiff but brittle.
They are poor electrical and thermal conductors and have high mp.
It is a giant covalent structure.

Clay ceramics are hard, waterproof, smooth, giant covalent.
Glass is also giant covalent but transparent.

Composite materials are made from 2 or more materials.
Concrete mixed with cement, sand and gravel.
Sand and gravel form the reinforcement of concrete.
Cement bonds the reinforcement together through reactions forming the matrix.
Steel reinforced concrete is more tensile and compressive.

Laminates have thin sheets of wood to form a matrix by gluing them perpendicular.

Question 5

9.39C - Explain why properties of a material make it suitable for its use

Answer 5

Polymers are strong, chemically unreactive and poor conductors.
Rigid PVC is useful for pipes and frames.
Flexible PVC is useful for water pipes and flooring.

Metals are strong, good conductors and malleable.
Metals can be mixed to form alloys.