purifying and testing water Flashcards
how is water used in industry and what is the benefit of it?
it is cheap
used as a coolant
a valuable solvent
what is in water before it is purified?
dissolved salts and minerals
pollutants
insoluble materials
microbes
what pollutants may get into tap water?
nitrate residues
lead compounds
pesticide residues
what are the main 3 stages of water purification?
sedimentation of particles
filtration of fine particles
chlorination (kills microbes)
which 2 pollutants come from agriculture?
nitrates from fertiliser run off
pesticides from spraying near to water courses
what is the benefit of getting water from a bore hole?
it is usually always pure so it needs little treatment
which stage in distillation makes the process so expensive?
energy levels required
suggest why the chlorination stage of water purification comes last?
so no more poisonous substances can get in before it gets to the tap
what happens in a precipitation reaction?
a solution is taken, it is added to another solution, the solutions react to create a preciptate
why would water supply stop working if there was a power cut?
because energy is required to pump the water to homes
why is seawater undrinkable?
it has so many substances dissolved in it
what is the disadvantage of distillation?
it takes huge amounts of energy
