Water%20Hardness%20Notes

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Water Hardness Notes

• Applied Chemistry
• Atom Unit

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Water Hardness

• A. Definition water hardness is a measure of
  the amount of salts dissolved in water.
• 1. Salts dissolved in water to produce ions,
  which are charged particles.
• Salts are present in the ground as minerals.
• Surface water usually contains low levels of
  hard-water ions.

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Water Hardness

• Ground water that flows through limestone,
  dolomite, magnesite, or gypsum dissolve salts
  that result in high levels of hard-water ions.
• Hard-water ions include Ca2, Mg2, or Fe3

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Measurement water is usually tested for Ca2

• Units
• Parts per million ppm
• 1 milligram per liter 1 ppm
• Grains per gallon
• 1 grain/gallon 17 ppm

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Measurement

• Range of values
• Soft water less than 120 ppm
• Moderately hard water 120-350 ppm
• Very hard water over 350 ppm

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Types of Hardness

• Temporary hardness is hardness that can be
  removed by boiling
• Permanent hardness is hardness that cannot be
  removed by boiling

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Hard Water Use

• 1. Need more soap for cleaning.
• 2. Forms scum when hard-water ions react with
  soap.
• 3. Forms scale, a build-up in tea kettles and hot
  water heaters.

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Treatment of Hard Water

• 1. Water softeners are installed within your home
  plumbing.
• These units contain an ion exchange resin which
  are tiny, insoluble, porous beads.
• Hard water passes over the ion exchange resin and
  the unwanted Ca2, Mg2, and Fe3 are exchanged,
  or traded, for Na1.
• Health concern increased levels of sodium in
  your diet.
• Solution by-pass on kitchen sink

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