C6.2 Flashcards
what are the three main stages of the life of a product?
-cradle
-use
-grave
describe the cradle stage
-raw materials used and how they are produced
-useful materials and how they are used to manufacture the product
-energy and water used during processing and manufacturing
describe the use stage
-energy requirements for using product
-energy required to maintain product
-water and substances required to maintain product
describe the grave stage
-space needed to dispose of product
-energy required to dispose of product
-impact on environment
factors that effect how easily materials can be recycled
-how easily the waste can be collected, sorted and stored
-the amount and type of any by products released by recycling
-the cost of recycling compared to disposal in landfill or by incineration
-the amount of energy involved at each stage
how are materials recycled?
-metals are melted by heating and poured into moulds to produce new blocks called ingots
-paper is mixed with water, cleaned, then rolled and heated to make new paper
-glass is melted by heating, and moulded into new glass objects
-polymers like poly(ethene), PET and poly(propene) are sorted and melted to form new objects
what is a life cycle assessment or ‘cradle to grave analysis’?
a part of legislation put into place to protect the environment
what is the point of a life cycle assessment?
to make companies consider their use of natural resources and minimise the environmental impact their product has
why is recycling important?
-conserving limited raw materials and energy
-reducing the release of harmful substances into the envronment
air pollutants
substances released into the atmosphere that may harm living things
how are many atmospheric pollutants released?
as a result of burning fossil fuels
incomplete combustion
limited O2 supply
how is water purified?
-filtration
-sedimentation
-chlorination
describe filtration
a wire mesh screens out large twigs etc. and then (after sedimentation takes place) a sand and gravel bed filters out any other solid bits
describe sedimentation
sedimentation (with coagulation)- iron sulfate or aluminium sulfate is added to the water, which makes fine particles clump together and settle at the bottom
describe chlorination
chlorine gas is bubbled through to kill harmful bacteria and other microbes
how is salt water treated?
-dissolved salts removed via a process called desalination
-for large scale desalination, simple distillation is used, which uses a lot of energy and can therefore be expensive
what is the gas test for carbon dioxide?
bubbled through limewater turning it cloudy
what is the gas test for hydrogen?
lighted splint burns rapidly with a pop sound
what is the gas test for oxygen?
glowing splint relights
what is the gas test for chlorine?
litmus paper is bleached and turns white
what are the main gases in the earths present atmosphere been made up of?
made up of gases similar to those released by a volcano: primarily water vapour and carbon dioxide
describe the evolution of the earths atmosphere
- the early earth was a hot, violent place with many active volcanoes
- the early atmosphere was made up of gases released by volcanoes- mainly carbon dioxide and water vapour
- the temperature on earth eventually cooled, causing water vapour to condense and form oceans
- some of the carbon dioxide in the atmosphere began to dissolve in the oceans and later became incorporated into sedimentary rocks
- life on earth began to evolve and microscopic organisms and early plant life made their food by photosynthesis, using carbon dioxide and releasing oxygen
- the natural atmosphere is now made up of mostly: nitrogen and oxygen
what are the different air pollutants?
-carbon monoxide
-carbon particulates (soot)
-nitrogen monoxide
-nitrogen dioxide
-sulfur dioxide
how is carbon monoxide produced?
formed from the incomplete combustion of carbon based fuels
how are carbon particulates produced?
formed from the incomplete combustion of carbon based fuels
how is nitrogen monoxide produced?
at high temperatures the N2 and O2 in the air react
how is nitrogen dioxide produced?
2NO + O2 –> 2NO2
how is sulfur dioxide produced?
formed when sulfur impurities in fuel burns- volcanoes
how is carbon monoxide harmful?
-toxic gas
-prevents oxygen from binding to haemoglobin
how are carbon particulates harmful?
-causes respiratory problems
-makes surfaces black and dirty
what happens to nitrogen monoxde?
quickly oxidises to form NO2
how is nitrogen dioxide harmful?
-causes respiratory problems
-causes acid rain which corrodes buildings, kills plant life and aquatic life
how is sulfur dioxide harmful?
-causes respiratory problems
-causes acid rain
what is the greenhouse effect?
a natural phenomenon that keeps the earth and its atmosphere warm enough for living things to exist
what are the different parts of the greenhouse effect?
- infrared radiation from the sun hits the earths surface
- infrared warms the surface
- infrared is emitted by the surface- some goes into space; some is trapped/absorbed by greenhouse gases
- greenhouse gases emit infrared in all directions warming the atmosphere
give an example of a causal correlation
there is a causal correlation between CO2 levels and global temperature, as if there are more CO2 molecules in the atmosphere, more infrared heat will be trapped
what is the enhanced greenhouse effect?
-the release of additional greenhouse gases by human activities
-this has the potential to cause the average temperature on earth to rise
-this global warming leads t melting ice caps and rising sea levels, and to climate change
-climate change brings altered weather patterns
how can greenhouse emissions be reduced?
-reducing the consumption of fossil fuels, e.g. by using biofuels
-using renewable energy resources e.g. wind to generate electricity
-stopping carbon dioxide escaping when fuels are burnt by using carbon capture
desalination
removes salt from brine leaving water behind
filtering
insoluble particles are removed from water
distillation
mixture containing water is heated until the water turns into steam, then the steam is condensed and pure water is collected
sterilising
adding chemicals to water to pathogens
chlorine
a chemical that is added to water to kill harmful bacteria
reservoir
a place where large amounts of water is stored
potable
water that is safe to drink
aquifer
a rock that contains water
fresh water
water that contains low levels of dissolved salts
describe the process of water purification
- the water is stored in a reservoir
- filtration: filters out large solids
3.water passes through a wire mesh - water passes through a settlement tank
- sedimentation/coagulation: coagulants are added to clump finer solids together which settle to the bottoms
- filtration: filters out any remaining solids
- chlorination: chlorine added to kill any pathogens
- final checks e.g. pH
