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Not all water is created equally.
Water has the unique ability to dissolve a wide variety of
materials. Some Industries can not use water with materials
that may be present naturally because they would cause
adverse effects to the machinery of the facility, the
product,or the environment. A power plant is an example in
point. The presence of such dissolved solids as Magnesium,
iron, calcium and others require the power company to expend
more energy than normal to raise water to its boiling point.
In addition to energy waste these materials can quickly lead
to a mechanical hardening of the arteries as they
precipitate out inside steam tubes.
People are also affected by this
problem. When using soaps in water with a high mineral
content it will be difficult to raise a lather because
compounds in the water must be precipitated from the
solution before sudsing can occur. In addition, mineralized
water will leave a film or "soap scum" around the washing
surface that will be difficult to remove.
Water that contains large amounts of
calcium and magnesium is said to be "hard water". Hard water
usually occurs in areas where limestone rock can be
dissolved by water that is slightly acidic. The acid in
water comes from carbon Dioxide. A waste product of animal
respiration, CO2 makes up 0.03 percent of the air we
breathe. When combined with water, carbon dioxide forms a
weak acid. This Carbonic acid eats away at limestone or
magnesium rich earth and produces calcium or magnesium
carbonate. These are the compounds that are most frequently
associated with the production of water hard. Iron, aluminum
and other minerals may cause hardness if enough of them are
present in a given quantity of water. However, large amount
of these minerals are not usually found in natural
waters.
Hardness tests are frequently
performed in industries that rely on pure water. These tests
measure the total amount of calcium and magnesium in a water
sample and express the results in metric units as milligrams
per liter (mg/L) of calcium carbonate (CaCo3), or the
English units of grains per gallon (gpg) of calcium
carbonate. To convert from metric units to the customary
English unit simply apply the formula :
mg/L = gpg X
17.1
Water is said to be hard when its
total hardness exceeds 121 milligrams per liter of calcium
carbonate.(condensed from Water,Water Everywhere, Teacher's
Guide and experiments by Cliff Jacobson)
Not all materials dissolved in water
are necessarily harmful. Some elements in small amounts can
be quite beneficial. Small amounts of fluoride can help
prevent tooth decay, and water companies frequently add
chloride to cut down on the number of micro organisms that
that would reproduce in our drinking water and make us
sick.
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