26 - Bulk & Surface Properties of Matter (Including Nanoparticles)

Question 1

What are the properties of Glass?

Answer 1

• Transparent
• High mp
• Brittle
• Poor conductors of heat & electricity

Question 2

How is glass made?

Answer 2

Glass is made by melting sand with other substances (especially metal oxides), then allowing the molten liquid to cool and solidify

Question 3

What are the properties of Clay?

Answer 3

• Opaque
• High mp
• Brittle
• Poor conductors of heat & electricity

Question 4

How are clay ceramics made?

Answer 4

They are made by heating clay to high temperatures, which causes crystals to form and join together

They are often coated with a glaze

Question 5

What is the purpose of the glaze in clay ceramics?

Answer 5

Forms a hard, smooth, opaque and waterproof layer

Question 6

Give some examples of clay ceramics

Answer 6

• Brick
• China
• Porcelain

Question 7

What are the properties of Metals?

Answer 7

• Shiny
• High mp
• Malleable
• Good conductors of heat & electricity

Question 8

What are the properties of Polymers?

Answer 8

• Poor conductors of heat & electricity
• Rest of the properties depends on the particular polymer

Question 9

What is a composite material?

Answer 9

Material made from two or more different materials with contrasting properties

Question 10

What are the components that most composite materials have?

Answer 10

• The reinforcement
• The matrix, which binds the reinforcement together

Question 11

What is the matrix?

Answer 11

The substance that binds the reinforcement together in a composite material

Question 12

What is reinforcement?

Answer 12

Fibres or other material that make up the bulk of a composite material

Question 13

What is Tensile strength?

Answer 13

The tension a material can withstand without breaking

Question 14

What are some examples of composite materials?

Answer 14

• Reinforced concrete
• Fibreglass
• Chipboard
• Carbon fibre reinforced polymer

Question 15

What is the matrix in the Reinforced concrete composed of?

Answer 15

Concrete

Question 16

What is the reinforcement in the Reinforced concrete composed of?

Answer 16

Steel

Question 17

How does reinforcing concrete with steel improve concrete’s physical properties?

Answer 17

• The compressive strength of concrete is higher than its tensile strength.
• The tensile strength of steel is higher than its compressive strength.

–> The combination of these 2 materials makes the reinforced concrete strong in tension and in compression.

Question 18

Why is important that reinforced concrete has high compressive and tensile strength?

Answer 18

This allows reinforced concrete to be strong and slightly flexible, which is important when constructing large buildings and structures

Question 19

What is the matrix in the Fibreglass composed of?

Answer 19

Polymer resin

Question 20

What is the reinforcement in the Fibreglass composed of?

Answer 20

Glass fibres

Question 21

What is the matrix in the Carbon fibre reinforced polymer composed of?

Answer 21

Polymer resin

Question 22

What is the matrix in the Chipboard composed of?

Answer 22

Resin glue

Question 23

What is the reinforcement in the Carbon fibre reinforced polymer composed of?

Answer 23

Carbon fibres

Question 24

What are some properties of Fibreglass and carbon fibre?

Answer 24

• Low density (lightweight)
• Strong in tension

Question 25

What is the key *property* of the **polymer resin** used in *Fibreglass & Carbon fibre*?

Answer 25

It is not strong but it is stiff

Question 26

What is the key *property* of the **fibres** used in *Fibreglass & Carbon fibre*?

Answer 26

It is strong in tension (so it's not easily stretched) but they are flexible

Question 27

What is the **reinforcement** in the **Chipboard** composed of?

Answer 27

Wood chips

Question 28

What are the *properties* of a **Chipboard**?

Answer 28

Very Strong

Question 29

Why are **chipboards** very strong?

Answer 29

Chipboard contains randomly arranged wood chips bonded together by a glue, so it is strong in all directions

Question 30

What is the **reinforcement** in **wood** composed of?

Answer 30

Cellulose fibres

Question 31

What is the **matrix** in **wood** composed of?

Answer 31

Lignin

Question 32

Why is *wood* stronger in one direction than the other?

Answer 32

The cellulose fibres of wood are aligned alongside each other

Question 33

What are **nanoparticles**?

Answer 33

Tiny particles which are between 1 and 100 nanometres (nm) in size

Question 34

What is a **nanoparticulate**?

Answer 34

Useful substances containing nanoparticles

Question 35

What does the uses of **nanoparticulates** depend on?

Answer 35

* Small size of the nanoparticles * Large surface area to volume ratios

Question 36

How **big** are nanoparticles in *comparison* with atoms?

Answer 36

They typically consist of just a few hundred atoms

Question 37

What are some **uses** of **nanoparticulate materials**?

Answer 37

* Sunscreens * Catalysts * Stain-resistant clothes

Question 38

What is **titanium dioxide** in *bulk*?

Answer 38

A white solid

Question 39

How does the *nanoparticulate* **titanium dioxide** look like?

Answer 39

Its transparent because the particles are very small

Question 40

What does **titanium dioxide** do?

Answer 40

Absorbs harmful UV radiation present in sunlight

Question 41

What is **titanium dioxide** found in?

Answer 41

Sunscreens (especially the sunscreens which are almost invisble)

Question 42

How are **nanoparticulate materials** useful as **catalysts**?

Answer 42

The very large surface area : volume ratios allow them to act efficiently as catalysts They: * Catalyse reactions more efficiently * Catalyse different reactions * Produce different products

Question 43

How do **stain-resistant clothes** treated with *nanoparticles* stay clean?

Answer 43

The nanoparticles catalyse the breakdown of dirt

Question 44

What are some **risks** of **nanoparticulate materials**?

Answer 44

Small size - makes it possible to breathe them in or pass into cells

Question 45

Why might it be *dangerous* that **nanoparticles** can **pass into cells**?

Answer 45

They might catalyse reactions that are harmful Toxic substances could bind to them because of their large surface area to volume ratios, harming health if the nanoparticles do get into the body.

Question 46

Why are the **risks** of *nanoparticles* difficult to determine?

Answer 46

Modern nanoparticulate materials have not been in use for long