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

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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
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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
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4
Q

What is thermosoftening?

A

Thermosoftening polymers soften when heated and can be reshaped but harden again when cooled

eg LDPE

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5
Q

What is thermosetting?

A

Thermosetting polymers harden for good once cool

eg HDPE

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