polymers

Question 1

Define polymers

Answer 1

long chain molecule made by combining repeating similar basic units

Question 2

What are the three types of polymer. Give 1 example of each type of polymer

Answer 2

• thermoplastic polymer - PVC, nylon
• thermosetting polymer - bakelite, melamine
• elastomers polymer - rubber

Question 3

state 1 property of elastomers polymer

Answer 3

• can be stretched and return to original shape

- posseses high elasticity properties

Question 4

Which type of polymer will degrade after being heated and cannot be moulded into different shapes?

Answer 4

• thermosettign polymer

Question 5

What method can be used to polymerize an alkene?

Answer 5

• addition polymerisation

Question 6

give examples of polymers produced by addition polymerisation

Answer 6

• polyethene
• polychloroethene
• polypropene
• polystyrene

Question 7

What type of polymerisation method can be used when combining 2 different monomers.
give and example of polymer produced with this method

Answer 7

• condensation polymerisation

- nylon, terylene

Question 8

What polymer is used to make toys and textile. State the properties which support its uses

Answer 8

• polypropene

- durable

Question 9

what are the properties and uses of polyethene

Answer 9

• strong and durable

- plastic bags, plastic containers

Question 10

in condensation polymerisation, polymer and ____ or _____ is produced

Answer 10

• water or hydrogen chloride

Question 11

Give 3 properties of synthetic polymers

Answer 11

• lightweight, strong and hard
• inert and chemically unreactive
• good heat and electical insulators
• resistant to heat

Question 12

What is the monomer for polyisoprene

Answer 12

Isoprene, 2-methylbut-1,3-diene

Question 13

What causes rubber to oxidize when exposed to air

Answer 13

• presence of carbon-carbon double bond , C=C

Question 14

Explain 3 characteristics of natural rubber

Answer 14

• elastic: can be stretched and release to original shape
• low resistance toward heat : becomessticky when exposed to high temperature
• good electrical insulator : cannot conduct electricity at all
• reactive to chemicals: can react with acid, base and organic solvent
• waterproof: impermeable to water
• easily oxidised : O2 reacts with double bond

Question 15

Latex can coagulate naturally when exposed to air or by _____

Answer 15

• adding methanoic acid

Question 16

Explain coagulation of latex with methanoic acid

Answer 16

• latex is a aqueous suspension of colloidal rubber particles
• the rubber particles are surrounded by a layer of protein membrane
• the layer of protein membrane is negatively charged causing rubber particles to repel against one another thus preventing coagulation
• Methanoic acid ionize to form hydrogen ions
• hydrogen ions will neutralize the negative charges on the protein membrane
• When rubber particles collide, the protein membrane breaks and rubber polymers coagulate

Question 17

Latex can coagulate when exposed to air due to the presence of ___ which produces ____

Answer 17

• bacteria

- lactic acid

Question 18

How to prevent coagulation of latex?

Answer 18

• add ammonia

Question 19

what process is done to make natural rubber more elastic and has better quality?

Answer 19

• vulcanisation of rubber

Question 20

State the catalyst, substance and condition needed for vulcanisation of rubber with sulphur

Answer 20

Sulphur is heated with natural rubber at 140 oC with zinc oxide as catalyst

Question 21

Why cant some rubber be vulcanised with sulphur?

Answer 21

• they do not have carbon carbon double bond

Question 22

How does vulcanisation of rubber can increase quality and elasticity

Answer 22

• sulohur atoms added to carbon carbon double bond of rubber will form sulphur cross links between long polymer chain

Question 23

Explain the properties of vulcanised rubber in terms of elasticity

Answer 23

• when vulcanised rubber is stretched, the sulphur cross links prevents the polymer chains from slipping past one another
• when the stretched vulcanised rubber is released, the sulphur cross links pull the polymer chains back to its original position
• thus, vulcanised rubber is more elastic

Question 24

How does vulcanising rubber increases its resistance towards heat?

Answer 24

• addition of sulphur atoms increases molecular mass of rubber
• Van Der Waals foa between rubber molecules become stronger
• more heat energy is needed to overcome the stronger VDW foa between rubber molecules during heating
• melting point of rubber increases

Question 25

State a use of thiokol (type of synthetuc rubber)

Answer 25

Sealant

Question 26

What type of rubber can be used to make rubber glover?

Answer 26

• neoprene, nitrile rubber