CHEMISTRY Flashcards
what happens in electrolysis?
requires a liquid to conduct electricity
Positive ions move towards negative electrodes
what does electrolysis extract? and what does it do and what is required?
metals more reactive than carbon.
makes it pure
high temperature & energy
what are the advantages of quarrying?
- used as building materials
- limestone products from thermal decomposition used to neutralise soils
- used in power station chimneys to neutralise sulphur dioxide
what are the disadvantages of quarrying?
- permanently changes the landscape
- noise and dust pollution
what other 2 methods could we use to extract small bits of copper?
low grade ores - bioleaching and phytomining
how does bioleaching work?
bacteria gets energy from bond between copper and sulfur separating out the copper. Leachate is produced containing copper and extracted by filtering
how does phytomining work?
low grade ore
grow plants in soil containing copper, builds up in leaves, plants harvested and burnt in a furnace, copper collected from ash.
where is crude oil from?
buried remains of plants and animals
advantages of crude oil?
good fuels for transport
reliable
cheap
what are the disadvantages of crude oil?
non-renewable
oil spills- birds poisoned
causes global warming and acid rain
what are 3 alternatives fuels for crude oil?
ethanol
biodiesel
hydrogen gas
how is ethanol produced?
produced from plant material made by the fermentation of plants
what are the pros of the alternative fuel of ethanol?
carbon neutral and it’s only other product is water - no pollution
what are the cons of ethanol fuel?
engines need to be converted and isn’t widely available
how is the alternative fuel biodiesel produced?
by vegetable oils & rapseed oils
what are the pros and cons of biodiesel?
carbon neutral, produces less sulphur dioxide & engines don’t need to be converted
expensive
how is hydrogen gas produced?
electrolysis of water
what are the pros of hydrogen gas?
very clean only forms water
need special expensive equipment & isn’t widely available
what is cracking?
long chain molecules like diesel into short chain molecules like petrol paraffin and ethene
what type of reaction is cracking?
thermal decomposition
what are the conditions needed for cracking? what are the products?
high temperature to vaporise it then passed over a catalyst. produces alkenes
what is polymerisation?
joining lots of alkenes together
how do you convert ethene to ethanol? pros, cons?
hydrated with steam in presence of a catalyst.
cheap
ethene is produced from a non renewable resource
how else could you get ethanol but from renewable resources?
fermentation - sugar (from plants) = carbon dioxide + ethanol
how do you get oils from plants?
plant material is crushed, then you press the crushed plant and squash the oil out.
what are the uses of extracting oils from plants?
provides humans energy, high boiling point than water - cook foods faster, rapeseed oil turned into biodiesel