Water Treatment

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Water Treatment
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What is the chemical formula for water??

• H2O
• What do these letters mean? (Look at the periodic
  table)
• H Hydrogen O Oxygen
• Water is 2 Hydrogens (H2) bonded to 1 Oxygen (O)

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• Is water a compound or an element??
• Remember to test for water COBALT CHLORIDE PAPER
  is used it turns from blue to pink if water is
  present
• Test this in class

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The Hoffman Voltameter

• We can use this to prove that water is made of
  Hydrogen and oxygen

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What exactly is happening??
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Properties of Water

• Freezing point of 0C
• Boiling point of 100C
• What do you think would happen if a bottle full
  to the brim with water was frozen?
• Water expands when it freezes this is why bottles
  and pipes burst in cold weather!

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An unusual fact

• Ice floats on water because it is less dense than
  water
• This is why fish and other organisms can survive
  in a lake as the top freezes over but because
  this floats on the surface life can continue
  underneath!

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Water as a Solvent

• What does dissolved mean?
• Do you think water is a good solvent?

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Experiment
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What kinds of things might be in water that we
cant see?

• Chemicals
• Bacteria
• Viruses
• Salt
• Poisons
• Toxins

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How do we make sure our water is clean?
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It is important to understand what each of these
stages involves
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Watch the following video clip from Unicef

• C\Documents and Settings\Laptop\Desktop\Carol
  School Work\UNICEFWatertreatment.gvp

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2nd watch with questions!!

1. What is a big problem in this area?
2. What stage of water treatment is being used?
3. Why is this stage being used?
4. How many people drink this water?
5. What happened to the 20 month old baby?
6. How is further prevention being carried out?

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Are there harmless things dissolved in water??
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How do calcium ions get into the water??
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• As we can see from the water cycle the water
  falls as rain back to earth and then drains into
  rivers, lakes and oceans
• If the rain flows through a limestone region
  (such as the Burren) it can dissolve the calcium
  in the rock and become hard
• NB Hard water is not ice!!

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What does hard water mean??
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Experiment to test water samples for hardness
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You can easily do this at home by mixing soap
with your water and seeing if it will form a
lather or not!!
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There are disadvantages and advantages to having
hard water can you think of any??
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Do you think it is possible to remove hardness
from water??
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Summary