Carbon Chemistry - Polymerisation Flashcards

1
Q

Why alkenes not used as fuels?

A

Because the double bond means that they undergo incomplete combustion.

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2
Q

Why are alkenes used to make polymers?

A

Because their double bond can be broken, allowing many alkenes to be joined together to make polymers.

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3
Q

What does polymerisation require? (3)

A
  • High temperatures
  • High pressures
  • Presence of a catalyst
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4
Q

What state are polymers are room temperature?

A

Solid because they are long-chained hydrocarbons

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5
Q

Why do the molecules form strong chemically resistant fibres?

A

Because the carbon chain length is bonded with strong covalent bonds.

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6
Q

What to remember when drawing the formulae of polymers

A
  • Brackets
  • THE N OUTSIDE THE BRACKET
  • NAMED AFTER ALKENE
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7
Q

What is a monomer?

A

A small molecule that can be combined with other molecules to make long chains.

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8
Q

Briefly outline the process of cracking

A

Alkenes are unsaturated hydrocarbons meaning the double bond can be broken, allowing many alkenes to join together. Each alkene molecule is called a monomer. In the presence of high temperature, high pressure and a catalyst, the bonds are broken and neighbouring alkenes are joined together to form polymers which are very long-chained hydrocarbons.

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9
Q

What is polypropene used for?

A

-Packaging, labelling, textiles (ROPES, THERMAL UNDERWEAR and carpets), stationery, reusable containers of various types, bottle caps, DRINKING STRAWS, yoghurt containers, appliances, car parts, LABORATORY EQUIPMENT, loudspeakers, margarine tubs and polymer bank notes.

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10
Q

Why is polypropene used to make fabrics, food containers etc

A
  • low chemical reactivity (with air, water and living organisms)
  • excellent resistance to concentrated acids, alcohols, bases and mineral oils
  • INSOLUBLE IN WATER
  • can be moulded or extruded into a wide range of shapes with moderate heating
  • thermal insulator
  • floats (less dense than water)
  • recyclable
  • excellent resistance to stress and is highly resistant to cracking.
  • DOES NOT PROMOTE GROWTH OF BACTERIA
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11
Q

Uses of polyethene

A

HDPE: low pressure and heat and catalyst, long linear straight chains.
-pipes, margarine tubs, rubbish bins, plastic bottles

LDPE: high pressure and heat and catalyst, chains with branches
-gladwrap and soft tubing

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12
Q

Why are polymers (polythene and polypropene) chemically unreactive?

A

because all valence electrons are used in single covalent bonds.

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13
Q

Describe polymers

A

Macromolecule and a hydrocarbon made up of repeated monomers of alkenes.

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