Flashcards in C2 Deck (43):
Definition of melting point?
The temperature a which a solid turns into a liquid
What is density?
Mass of a given volume of the material
When should outliers be discarded?
Only if there was an error in the measurement.
How do you get the true value?
By calculating the mean
Name 3 properties of metals
Shiny, malleable, and electrical conductors
Can all metals conduct electricity?
What are Natural materials?
Materials from living things which require little processing.
Give 2 examples of natural materials?
Silk and wool
What are Synthetic materials?
Materials that are manufactured by chemical reactions using raw materials.
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
What are hydrocarbons made of?
Hydrogen and Carbon atoms
What is crude oil made up of ?
A Mixture of hydrocarbons
How do you seperate crude oil?
Using fractional distillation
How does FD seperate crude oil?
It seperates them using boiling points
As the hydrocarbon chain length increases...
The forces between these molecules increase.
Why do larger molecules have higher boiling points
Because they need more energy to break intermolecular forces
The smaller the molecule chain...
the lower the boiling point.
What is a polymer?
A chain of monomers
What is the process that makes a polymer?
When are the forces strongest?
The closer they are, the stronger they are.
The stronger the force...
The more energy is needed to seperate the molecules and the higher the melting point.
What does LDPE stand for?
Low density polyethene
What are the properties of LDPE ?
LDPEs have BRANCHES which make the intermolecular forces weak
What are the properties of HDPE?
HDPEs Dont have branches which makes the intermolecular forces strong
Give an example of LDPE and HDPE?
Carrier bags and Water pipes
What do plasticisers do?
Plasticisers make polymers softer by keeping the chains apart and weakening the forces between them
What can soften when heated and be moulded into shape.
What contains cross-links and cannot soften when heated
How can Crytallinity be increased?
By removing branches, making the chain as flat as possible
What are Nanoparticles?
Material containing up to a thousand atoms
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
What are structures made up of nanoparticles measured in?
Why are nanoparticles effective catalysts?
Because they have a large surface area. Increasing the surface area provides more sites for reactions to take place.
What type of nanoparticle kills bacteria?
What are Titanium oxide nanoparticles used in?
Sunscreen as the make it transparent and absorb UV light
What do you get when you mix Nanoparticles with metals or ceramics?
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
What is Nanotechnology?
The science of making and using nanoparticles
Why are Silver nanoparticles dangerous?
They can be washed out of clothing, get into the sewage system and kill good bacteria.
TRUE OR FALSE: Nanoparticles cant pass through the skin into blood?
FALSE, They can and the effects are unknown.
Why are people afraid of nanoparticles in the air?
Because if breathed in , they could cause lung or brain damage.
Why are some not afraid of nanoparticles?
Because they occur naturally like in soot and volcanic dust