C6.2 Flashcards
(49 cards)
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
