1. Water Hardness Notes Applied Chemistry Atom Unit

2. 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.

4. 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 Ca +2, Mg +2, or Fe +3

5. Measurement: water is usually tested for Ca +2  Units: –Parts per million ppm –1 milligram per liter = 1 ppm –Grains per gallon –1 grain/gallon = 17 ppm

6. Measurement  Range of values –Soft waterless than 120 ppm –Moderately hard water120-350 ppm –Very hard waterover 350 ppm

7. Types of Hardness  Temporary hardness is hardness that can be removed by boiling  Permanent hardness is hardness that cannot be removed by boiling

8. 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.

10. 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 Ca +2, Mg +2, and Fe +3 are exchanged, or traded, for Na +1. –Health concern: increased levels of sodium in your diet.  Solution: by-pass on kitchen sink