Hard Water and Soft Water

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Properties of Water

  • Compound of Hydrogen and Oxygen - Hydrogen Oxide
  • Colourless, odourless liquid at room temperature
  • Solid water is ice and gaseous water is steam.
  • Good Solvent
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Definitions

Water Of Crystallisation

Water that is chemically bonded into a crystal structure

Hydrated

Water of crystallisation is present

Dehydration

Removal of water of crystallisation

Anhydrous

Water of crystallisation is not present

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Heating Copper Sulfate Crystals

When copper sulfate crystals are heated...

Colour change: blue to white

Equation: CuSO4 . 5H2O > CuSO4 + 5H2O

  • Condensation on test tube
  • Steam from mouth of test tube
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Three Tests for Water

1.  Anhydrous Copper Sulfate - white to blue

2. Cobalt Chloride Paper - blue to pink

3. Melting and boiling point tests

(1 and 2 are chemical tests)

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Testing water for hardness

1.  Measure out 25cm3 of water using a pipette

2. Add water to a conical flask

3. Add a little soap solution from a burette, shaking the flask.

4. Add more soap solution, a little at a time, until a lather lasting at least 30 seconds is obtained.

5. Record the volume of the soap solution used.

6. Repeat the procedure of each water sample: distilled, tap water, bottled water and boiled tap water.

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