Flashcards in C2 Deck (43):
1
Definition of melting point?
The temperature a which a solid turns into a liquid
2
What is density?
Mass of a given volume of the material
3
When should outliers be discarded?
Only if there was an error in the measurement.
4
How do you get the true value?
By calculating the mean
5
Name 3 properties of metals
Shiny, malleable, and electrical conductors
6
Can all metals conduct electricity?
YES!!!
7
What are Natural materials?
Materials from living things which require little processing.
8
Give 2 examples of natural materials?
Silk and wool
9
What are Synthetic materials?
Materials that are manufactured by chemical reactions using raw materials.
10
Why have synthetic materials replace natural materials?
1. Some natural materials are in short supply
2. They can be designed to give particular properties
3. They are cheaper and can be made in quantity needed
11
What are hydrocarbons made of?
Hydrogen and Carbon atoms
12
What is crude oil made up of ?
A Mixture of hydrocarbons
13
How do you seperate crude oil?
Using fractional distillation
14
How does FD seperate crude oil?
It seperates them using boiling points
15
As the hydrocarbon chain length increases...
The forces between these molecules increase.
16
Why do larger molecules have higher boiling points
Because they need more energy to break intermolecular forces
17
The smaller the molecule chain...
the lower the boiling point.
18
What is a polymer?
A chain of monomers
19
What is the process that makes a polymer?
Polymerisation
20
When are the forces strongest?
The closer they are, the stronger they are.
21
The stronger the force...
The more energy is needed to seperate the molecules and the higher the melting point.
22
What does LDPE stand for?
Low density polyethene
23
What are the properties of LDPE ?
LDPEs have BRANCHES which make the intermolecular forces weak
24
What are the properties of HDPE?
HDPEs Dont have branches which makes the intermolecular forces strong
25
Give an example of LDPE and HDPE?
Carrier bags and Water pipes
26
What do plasticisers do?
Plasticisers make polymers softer by keeping the chains apart and weakening the forces between them
27
What can soften when heated and be moulded into shape.
Thermoplastics
28
What contains cross-links and cannot soften when heated
Thermosetting
29
How can Crytallinity be increased?
By removing branches, making the chain as flat as possible
30
What are Nanoparticles?
Material containing up to a thousand atoms
31
Name 3 ways in which nanoparticles occur?
1. Naturally ie seasalt spray
2. by accident, in solid particulate when fuels burn
3. can be designed in laboratories
32
What are structures made up of nanoparticles measured in?
Nanometres (nm)
33
Why are nanoparticles effective catalysts?
Because they have a large surface area. Increasing the surface area provides more sites for reactions to take place.
34
What type of nanoparticle kills bacteria?
Silver nanoparticles
35
What are Titanium oxide nanoparticles used in?
Sunscreen as the make it transparent and absorb UV light
36
What do you get when you mix Nanoparticles with metals or ceramics?
Composites
37
Why would add nanoparticles to plastic sports equipment or tennis balls?
Adding them to sports equipment makes it stronger and makes tennis balls bounce longer
38
What is Nanotechnology?
The science of making and using nanoparticles
39
Why are Silver nanoparticles dangerous?
They can be washed out of clothing, get into the sewage system and kill good bacteria.
40
TRUE OR FALSE: Nanoparticles cant pass through the skin into blood?
FALSE, They can and the effects are unknown.
41
Why are people afraid of nanoparticles in the air?
Because if breathed in , they could cause lung or brain damage.
42
Why are some not afraid of nanoparticles?
Because they occur naturally like in soot and volcanic dust
43