alkenes

Question 1

double bond

Answer 1

one sigma one pi bond
pi bond makes C–C unable to rotate
-gives it fixed shape around the bond
- involves electrons in p orbitals to exist above and below plane of bond- no overlapping (unlike sigma)

Question 2

bond angles around C–C bond

Answer 2

three regions of negative charge
repel equally
120 degree angle
all in same plane

Question 3

stereoisomerism

Answer 3

possible due to double bond
rigid- cannot rotate around them
displayed at stereoisomerism
e- large groups on different sides
z- large groups on same side

Question 4

alkenes

Answer 4

react in additon reactions
alkenes are nucleophiles- high electron density between carbon atoms

Question 4

cahn ingold

Answer 4

four directly connecting atoms ordered by atomic mass
highest AM gets priority 1

Question 5

uses of electrophilic addition

Answer 5

bromine- test for alkenes ( orange -> colourless in alkene)
bromine added to alkene via electrophilic addition
sulphuric acid + water- produces alcohols
- alkene + sulfuric acid= alkyl hydrogen sulfate –> diluted and distilled with water to produce an alcohol
sulfate ion removed by nucleophilic subsititution

Question 6

asymmetric electrophilic addition

Answer 6

multiple products could be produced
selectivity- one will be favoured over the other

Question 7

intermediate stability

Answer 7

• driven by CARBOCATION INTERMEDIATE STABILITY
  tertiary> secondary> primary carbocations
  more alkyl groups next to positive charge, more stable the intermediate is
  alkyl groups push electrons - help stabilise adjacent positive charge

Question 8

choosing product

Answer 8

consider intermediates formed
both will be formed but one major one minor
MOST STABLE carbocation will be major

Question 9

electrophilic attack

Answer 9

electrophile much have pos/ partial pos charge to be attracted to regions of neg charge
involves mechanism of heterolytic fission of electrophile molecule

Question 10

electrophilic attack 2

Answer 10

pos end attracted to electron dense region in C–C bond
- pi bond electrons attracted towards H and form covalent bond

Question 11

addition of negative ion

Answer 11

electrons from C–C bond covalently bonding with H atom
one carbon atom has pos charge now- carbocation

Question 12

poly(ethene)

Answer 12

high density- linear chains
low density- branched chains (flexible)
used in plastic bags,bottles, toys

Question 13

poly(chloroethene)

Answer 13

can be made flexible or rigid
used for pipes sheeting insulation cables

Question 14

poly(propene)

Answer 14

toys guttering windows

Question 15

poly(phenylethane)

Answer 15

packaging material/food trays
cups

Question 16

poly(tetraflouroethane)

Answer 16

coating non stick pans
cable insulation

Question 17

lack of polymer reactivity

Answer 17

hard to dispose of
most are not biodegradable

Question 18

recycling polymers

Answer 18

conserves fossil fuels
decreases waste in landfill

Question 19

method recycling polymers

Answer 19

sorted by type
chopped into flakes
washed and dried
melted
cut into pellets
used to make new products

Question 20

disposal/ recycling pvc

Answer 20

hazardous- high chlorine content + additives
release HCl when burnt + other toxic gases
high stored energy value- can be burnt to produce heat- steam turns turbine to produce electricity

Question 21

feedstock recycling

Answer 21

chemical and thermal processes reclaim monomers from waste polymers
used as raw materials to produce new polymers
able to handle unsorted unwashed polymers

Question 22

bioplastics

Answer 22

produced from plant starch, cellulose, plant oils and proteins
renewable + sustainable

Question 23

biodegradable polymers

Answer 23

broken down –microorganisms—> water + CO2 + biological compounds
used as bin liners for food waste so both compost

Question 24

photodegradable polymers

Answer 24

oil based
bonds weakened by absorbing light to start degradation OR light absorbing additives used