Plastics Flashcards
Explain how propene molecules form a polymer. You should name the polymer formed. (3 marks)
poly(propene) / polypropene
any two from:
- double bonds open up / break /become single
- propene molecules / monomers /they join / undergo addition polymerisation
- form chains / long molecules
Briefly give one advantage and one disadvantage for each of these methods with regards to plastics: reuse, recycle, burn, dump (4 marks)
Reused Advantages: -saves raw materials / crude oil - saves energy / fuel / transport - fewer bags needed / made - reduces carbon / CO2 emissions - reduces use of landfill - saves cost of a new bag - no waste Disadvantages: unable to reuse many times bags easily split Recycled Advantages: - saves raw materials / crude oil - saves energy / use of fuel - reduces carbon / CO2 emissions - reduces use of landfill - can be used for new products Disadvantages: - has to be collected /transported / washed / separated / melted ignore uses energy Burned Advantages - heat / energy released can be used (for heating / generating electricity) - reduces use of landfill Disadvantages - has to be collected / transported - wastes the resource / plastic - releases harmful gases / toxic gases / CO2 Dumped Advantages - collected / transported with household waste (slowly) biodegrades or produces methane which can be used as a fuel - (not biodegradable so) does not release CO2 / green house gas into the air - wastes the resource Disadvantages - plastic uses landfill - produces methane which is a greenhouse gas / could cause explosions - not biodegradable / take years to decompose
You are asked to decide which option for the disposal of poly(ethene) will be put forward in your area. You decide that recycling is the best option. Suggest one economic argument and one environmental argument that will be made against recycling. For each argument made, how will you persuade those making the argument to accept your option?
(You must use only one sentence for each argument made against your decision and only one sentence for your response to it.) (4 marks)
economic argument against recycling
any one from:
- poly(ethene) / plastic must be collected / transported / sorted / washed
- this uses (fossil) fuels which are expensive
environmental argument against recycling
any one from:
- uses (fossil) fuels that are non-renewable / form CO2 / CO / SO2 /NOx / particulates
- washing uses / pollutes water
counter arguments
any two from:
- collect / transport alongside other waste
- use biofuels (instead of fossil)
- landfill is running out
- landfill destroys habitats
- incinerators are expensive to build
- saves raw materials / crude oil
- saves energy needed to make new plastic
- incinerators may produce harmful substances
- incinerator ash goes to landfill
- poly(ethene) is non-biodegradable
- poly(ethene) can be made into other useful items
- more jobs / employment for people
Describe how ethene forms poly(ethene). (2 marks)
many ethene / molecules / monomers join to form a long hydrocarbon / chain / large molecule accept double bonds open / break accept addition polymerisation ignore references to ethane
PEX is a shape memory polymer. What property does a shape memory polymer have? (1 mark)
(can be deformed but) return to their original shape (when heated or cooled)
PEX is a material that is used as an alternative to copper for hot water pipes.
PEX is made from poly(ethene). Suggest the possible environmental advantages of using PEX instead of copper for hot water pipes. (4 marks)
any four from:
- less (hydrocarbon) fuels used
- less / no electrical energy used
- reduce carbon / carbon dioxide emissions
- reduce / no pollution by sulfur dioxide / acid rain
- continuous process
- conserve copper which is running out or only low-grade ores available
- reduce the amount of solid waste rock that needs to be disposed
- reduce the need to dig large holes (to extract copper ores)
allow less energy
allow no electrolysis
allow less global warming
allow less / no transportation
allow less waste
allow less mining
Give two reasons why a company would decide to increase the amount of hydrogel used in its nappy pads. (2 marks)
any two from:
- it was not the best (at absorbing the water)
- (needed) to absorb more (water)
- to improve their image / sales
Suggest one disadvantage for the company if it increases the amount of hydrogel used in its nappy pads. (1 mark)
- cost (more)
- use (more) resources
- use (more) energy
Poly(ethene) molecules are made from ethene molecules by a polymerisation reaction. Describe what happens in a polymerisation reaction. (2 marks)
many (ethenes / monomers)
bond / join together
Explain why different polymers have different properties. (1 mark)
Different polymers have different properties because their molecules are made up of different chemicals and are arranged in different ways
List one use each for LDPE and HDPE. Explain how the properties of each of these polymers make them suitable for these uses. (4 marks)
LDPE – packaging; suitable because it is flexible and waterproof.
HDPE – garden furniture; suitable because it is rigid and waterproof
Suggest two advantages of filling your teeth with a white polymer and not a mixture of metals. (2 marks)
The colour matches that of teeth. The material conducts heat less well than metals, so eating hot or cold food is not painful.
Use ideas about particles to explain why HDPE is stronger and has a higher melting point than LDPE. (2 marks)
HDPE polymer molecules have fewer side branches than LDPE, so HDPE molecules line up in a pattern close together. This means the molecules are held together more strongly in HDPE than in LDPE, so HDPE is stronger and has a higher melting point
