what do humans use the earths resources for
warmth, shelter, food, transport
how are most of earths resources made
agriculture
what are trees used for
timber and fuel
how is synthetic rubber produced
using crude oil
where does natural rubber come from
the sap of a tree
what does it mean when a resource is finite
they cant be replaced as quickly as theyre being used, theyll eventually run out
examples of finite resources
examples of renewable resources
wood
what does renewable mean
we can replace these resources as quickly as we use them, so theyll never run out
what does it mean when human activities are SUSTAINABLE
examples of how chemistry plays an important role in how we use resources
what does water have to contain to make it safe enough for humans to drink
what is potable water
water that is safe to drink
what is the difference between pure water and potable water
pure water contains no dissolved substances at all and has a ph of 7, whilst potable water contains dissolved substances, but in quite small amounts
where does most potable water come from in the UK and why
rainwater, it contains low levels of dissolved substances
- rain collects in the ground in aquifers and in lakes, rivers and reservoirs and all of these are good sources of fresh water
how to produce potable water
how is potable water produced in countries where the water is either to salty to drink
desalination
what does desalination do
it reduces the levels of dissolved minerals down to an acceptable level for potable water
how to carry out desalination
using distillation
- pass the water through membranes, reverse osmosis
disadvantages of desalination
require very large amounts of energy which makes them expensive
examples of what humans use water for
what does waste water contain
How is waste water treated step by step
why is the sewage passed through a mesh
removes solids and grit from the water