Unit 3: Section 7 - Polymers MDY *

Question 1

what does condensation polymerisation involve?

Answer 1

2 different types of monomer, each with at least 2 functional groups
the functional groups react together
a molecule of water is lost for each link form

Question 2

how are polyamides formed?

Answer 2

the carboxyl groups of dicarboxylic acids react with the amino groups of diamines
to form amide links

Question 3

how are polyesters formed?

Answer 3

the carboxyl groups of dicarboxylic acids react with the hydroxyl groups of diols to form ester links

Question 4

what is hydrolysis?

Answer 4

the reverse of condensation polymerisation

water molecules are added back in to break the links

Question 5

are condensation or addition polymers stronger?

Answer 5

condensation are generally stronger and more rigid

because they are made up of chains containing polar bonds

Question 6

what bonds are there between condensation polymers?

Answer 6

van der waals
permanent dipole-dipole
hydrogen bonds

Question 7

what are polyalkenes?

Answer 7

addition polymers
they are made up of non-polar carbon chains
so they are unreactive and chemically inert

Question 8

what are the effects of polyalkenes being unreactive?

Answer 8

useful - they can be used without reacting, durable

bad - they are non-biodegradable

Question 9

why are condensation polymers biodegradeable?

Answer 9

they have polar bonds in their chains, making them open to attack by nucleophiles
so can be broken down by hydrolysis
so biodegrade slowly

Question 10

how can plastics be disposed of?

Answer 10

burying
burning
sorting for reusing or recycling

Question 11

how can plastics be disposed of by burying?

Answer 11

landfill

Question 12

when is landfill used?

Answer 12

when plastic is:
difficult to separate from other waste
not in sufficient quantities to make separation financially worthwhile
too difficult to recycle

Question 13

advantages of landfill?

Answer 13

cheap

easy

Question 14

disadvantages of landfill?

Answer 14

requires areas of land
waste releases methane (greenhouse gas) as it decomposes
leaks can contaminate water supplies

Question 15

what happens when waste is burned?

Answer 15

heat used to generate electricity

Question 16

why does burning waste plastic have to be carefully controlled?

Answer 16

to reduce the release of toxic gases

e.g. polymers containing chlorine produce HCl

Question 17

how is burning waste plastic controlled?

Answer 17

waste gases from combustion are passed through scrubbers which can neutralise by allowing them to react with a base
but gases still contribute to greenhouse effect

Question 18

why are waste plastics recycled?

Answer 18

because many plastics are made from non-renewable oil-fractions

Question 19

how can plastics be recycled after being sorted?

Answer 19

some plastics can be melted and remoulded

some plastics can be cracked into monomers, and these can be used to make plastics or other chemicals

Question 20

what are the advantages of recycling waste plastics?

Answer 20

reduces amount of waste going into landfill
saves raw materials
cost of recycling is lower than making from scratch
produces less CO2 emissions than burning

Question 21

what are the disadvantages of recycling waste plastics?

Answer 21

technically difficult
collecting,sorting and processing more expensive than burning/landfill
often can’t remake plastic you started with
plastic can become contaminated

Question 22

what are polymers?

Answer 22

long chain molecules made from lots of small molecules joined together

Question 23

what are monomers?

Answer 23

small molecules that join together to make polymers

Question 24

what is addition polymerisation?

Answer 24

the formation of long chain molecules from lots of small molecules joining together with no other products
formed by double bond of alkenes opening up to form bonds

Question 25

why are addition polymers unreactive?

Answer 25

all the molecules are saturated