C2.2 Properties & Uses of Substances Flashcards
1
Q
Do electrons, protons, or neutrons define the element?
A
Protons
If you change the amount of protons, you change the element
2
Q
What is LDPE and what is it used for?
A
Low density poly ethene is used for plastic bags
- made at 100 -300 degrees at pressure of 1500 - 3000 atm
- branching from the main chains allows strength and stretch
- low density
3
Q
What is HDPE and what is it used for?
A
High density poly ethene is used for plastic garden chairs
- made at 300 degrees at a 1 atm pressure
- Aluminium based metal oxide catalyst used
- chains very close -> high denisity and melting point
4
Q
What is thermosoftening?
A
Thermosoftening polymers soften when heated and can be reshaped but harden again when cooled
eg LDPE
5
Q
What is thermosetting?
A
Thermosetting polymers harden for good once cool
eg HDPE
