Purifying Water Flashcards
Where do we get water resource from in the UK?
Surface water -
lakes, rivers and reservoirs (artificial lakes)
Groundwater -
aquifers (rocks that trap water underground)
How do you filter water ? (3 steps)
- Filtration -
wire mesh with gravel and sand beds - filter out solids - Sedimentation -
Iron sulfate or aluminium sulfate added to the water - make particles clump at the bottom - Chlorination-
Chlorine has bubbled through water and kill bacteria/microbes
Why is water still dangerous after purifying it?
Some impurities cannot be filtered out which causes water hardness
- harmful chemicals such as pesticides and fertilisers found
Why isn’t tap water 100% safe?
Many pollutants which come from:
- nitrate residues from fertilisers running off on lakes and rivers
(If overdosed in human, can be harmful for babies, the nitrate stop blood from carrying oxygen) - lead compounds from old lead pipes
(Lead is poisonous) - pesticide residues for spraying it too near to rivers and lakes
What is another way to get pure water without filtering it?
Distilling water
What is a disadvantage if distilling water?
Demands lots of energy, very expensive
Not suitable to produce large amount of fresh water
How do water companies test their pollutant level in water?
Check for dissolved ions by using precipitation (a reaction where 2 dissolved compounds form an insoluble solid)
How to test if sulfate ions are in water?
Using barium chloride - if a white precipitate occurs then there is sulfate ion In water
How to test if halide ions are in water ?
Using silver nitrate
Revise p72
4) reaction needed to know for exam
Chloride ions
Bromide ions
Iodine ions
