Purifying Water Flashcards

1
Q

Where do we get water resource from in the UK?

A

Surface water -
lakes, rivers and reservoirs (artificial lakes)

Groundwater -
aquifers (rocks that trap water underground)

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2
Q

How do you filter water ? (3 steps)

A
  1. Filtration -
    wire mesh with gravel and sand beds - filter out solids
  2. Sedimentation -
    Iron sulfate or aluminium sulfate added to the water - make particles clump at the bottom
  3. Chlorination-
    Chlorine has bubbled through water and kill bacteria/microbes
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3
Q

Why is water still dangerous after purifying it?

A

Some impurities cannot be filtered out which causes water hardness

  • harmful chemicals such as pesticides and fertilisers found
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4
Q

Why isn’t tap water 100% safe?

A

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
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5
Q

What is another way to get pure water without filtering it?

A

Distilling water

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6
Q

What is a disadvantage if distilling water?

A

Demands lots of energy, very expensive

Not suitable to produce large amount of fresh water

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7
Q

How do water companies test their pollutant level in water?

A

Check for dissolved ions by using precipitation (a reaction where 2 dissolved compounds form an insoluble solid)

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8
Q

How to test if sulfate ions are in water?

A

Using barium chloride - if a white precipitate occurs then there is sulfate ion In water

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9
Q

How to test if halide ions are in water ?

A

Using silver nitrate

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10
Q

Revise p72

4) reaction needed to know for exam

A

Chloride ions
Bromide ions
Iodine ions

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