LaMotte 1606 User Manual

HARDNESS IN WATER

L

Mott

CODE 1606

LaMOTTE COM PANY

Helping Peo ple Solve An a lyt i cal Chal lenges

PO Box 329 · Chestertown · Mary land · 21620 · USA

800-344-3100 · 410-778-3100 (Out side USA) · Fax [phone]

Visit us on the web at www.lamotte.com

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OXIDATION: Chemical change caused by oxygen reacting with the
substance.

pH: Based on the number of hydrogen or hydroxyl ions there are in a
substance. A pH scale is used to determine whether a substance is acidic,
basic or neutral. On the pH scale the midpoint 7.0 indicates a neutral
substance; readings below 7.0 are acidic; readings above 7.0 are basic.

POLLUTION: The presence of matter or energy whose nature, location
or quantity produces undesired environmental effects.

ppm: An abbreviation for parts per million. One ppm is equal to one
particle of the substance in a million particles of solution.

PURIFY/PURIFICATION: The process by which polluted substances are
cleaned. Purification can occur naturally, or by any of several mechanical
means, such as filtration or chemical treatment.

SCALE: Crusts or flakes which are deposited on the surface of metal parts,
often composed of calcium or magnesium.

SOLUTION: One or more substances dissolved in liquid.

WATER SOFTENERS: Special devices which remove minerals such as

calcium and magnesium from the water supply.

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GLOSSARY OF TERMS

TABLE OF CONTENTS

ACIDIC: The degree or level of acid content below 7.0 on the pH scale.

AQUATIC: Living or growing in a water environment.

BASIC: An alkaline material; usually relates to the degree or level of the

base content in a substance. A basic substance is above 7.0 on the pH
scale.

CALCIUM: A naturally occurring metal which is found in limestone,
chalk and gypsum. Calcium in water contributes to the overall hardness.

CHLORINATION: The process of adding chlorine compounds to
disinfect the water by destroying bacteria and algae.

COMPOUND: A pure substance composed of two or more chemical
elements.

DISINFECT/DISINFECTION: To destroy germs; the process of
destroying germs.

HARDNESS SOAP REAGENT: A standardized chemical solution of a
special detergent. Hardness Soap Reagent is added to a known volume of
water to determine the amount of hardness.

What is Wa ter?.............................................................................................4

Hard ness in Wa ter........................................................................................5

Taking Wa ter Sam ples..................................................................................6

Wa ter Hard ness: Method 1 ..........................................................................7

Wa ter Hard ness: Method 2 ..........................................................................8

Notes to the Teacher....................................................................................9

Glos sary of Terms ..................................................................................10-11

INDICATOR: A chemical compound added to a test sample which causes
a color reaction, showing the presence or absence of a particular substance.

MAGNESIUM: A naturally occurring metal. Magnesium in water
contributes to the over all hardness.

mL: An abbreviation for milliliter; equals one thousandth of a liter. A mL
is a measurement of very small volumes of liquid.

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WHAT IS WATER?

Water, a substance which covers approximately 75% of the Earth’s surface,
exists in three forms: solid, liquid and gas. In the solid form, ice, water is
used to cool drinks and other solutions, while the gas form, steam, can be
used to power turbines and engines. As a liquid, water is used in many
ways, from drinking to agriculture to providing homes for many kinds of
aquatic life.

Known as the universal solvent, “pure” water is able to combine with other
substances to form solutions. Even “natural” water found in the
environment contains dissolved gases, such as oxygen and carbon dioxide,
and dissolved minerals, such as iron and calcium. Although most of these
substances are not harmful at the levels commonly found, some substances
are toxic, or poisonous, to living things. Tests are available to determine
the levels of many toxic and nontoxic substances in water.

If dangerous or unhealthy substances are discovered, the water can be
treated to remove or destroy them. Some industries, such as agriculture, do
not need to treat water before using it, but others require water be purified
before use. For instance, many drinking water systems are treated with
chlorine to kill bacteria and disinfect the water, making it safe for
consumption. Other industrial processes add dangerous chemicals or
bacteria to the water, which must be removed or rendered harmless before
returning it to the environment.

Concern over the availability of usable water is increasing as the human
population increases. Polluted water will purify itself naturally over time,
but as more and more untreated, polluted water is returned to the
environment the system is overloaded and unable to work as well. Water
treatment processes, either chemical, biological or filtration, may be used to
supplement the natural purification process.

To determine the efficiency of treatment and levels of toxic and nontoxic
substances water must be frequently tested. When establishing a testing
program it is important to take samples over a period of time because the
character of the water constantly changes. By taking several samples,
determining their composition and keeping accurate records scientists are
better able to understand water.

NOTES TO THE TEACHER

The materials in this kit are provided as tools to conduct several
experiments. In addition to the procedures described in this manual, a
number of open-ended experiments are suggested to spur the student’s
imagination to investigate related problems. Students can use the materials
in this and other test kits to develop additional experiments.

ADDITIONAL EXPERIMENTS
FOR HARDNESS IN WATER

1. Obtain water samples from various natural water sources such as a
pond, stream or river. Test each sample for hardness and compare the
results.

2. Ask some students to bring in water samples from their homes. Test
the samples for hardness and compare results from municipally treated
water to untreated water.

3. Leave some containers out in the open to collect rain water. Test the
sample for hardness. How does rain water hardness compare to tap
water or water which was taken from a pond or a stream?

4. Add soil to one of the water samples before conducting a hardness
test. Mix thoroughly and filter. Test the filtered water for hardness.
What does the soil do to the hardness of the water sample?

5. Lime (calcium) is sometimes added to soil to adjust its pH. Add a
small amount of lime to a soil sample. In a funnel with filter paper
flood the soil sample with water and collect the water which percolates
through. Test the filtered water for hardness. What does lime do to
hardness of the filtered soil-water sample? How does this compare to
the sample in Experiment 4?

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WATER HARDNESS: METHOD II

1. Fill the test tube (0608) to the 10 mL line with sample water.

2. Use the pipet (0363) to add one drop of *Hardness Soap Reagent

(4768).

3. Cap and shake vigorously to form a lather. If sufficient lather does not
form, proceed to Step 4. If sufficient lather forms, proceed to Step 5.

NOTE: The lather should completely cover the surface of the solution
when the vial is laid in a horizontal position, and should last for five
(5) minutes.

4. Continue adding *Hardness Soap Solution (4768) drop by drop,
shaking and checking lather formation after each drop, until lather
forms and last 5 minutes. Count the total number of drops added.

NOTE: Be sure to include the drop added in Step 3.

5. Use the following chart to determine the sample hardness.

# OF DEGREE
DROPS OF HARDNESS RANGE

1-5 soft 20-100 ppm
6-10 hard 120-200 ppm
more than 10 very hard over 200 ppm

NOTE: Each drop of Hardness Soap Solution is equal to 20 ppm hardness.
The abbreviation “ppm” stands for parts per million; one ppm is equal to
one particle of substance in a million particles of solution.

HARDNESS IN WATER

Hardness is one of the common factors tested in water of all types and uses,
from environmental testing to drinking water to water used in industrial
processes. Defined as the amount of calcium and magnesium found in the
water, very high or low hardness levels can ruin expensive equipment, or
make water unsuitable for aquatic life.

Calcium and magnesium are elements found in many rocks, both above
and below the ground. As water passes over these rocks, the calcium and
magnesium slowly dissolve into the water. The amount of calcium and
magnesium dissolved into the water is dependent upon the hardness of the
rock. Rocks which dissolve easily and contain large amounts of calcium or
magnesium, such as sandstone and limestone, release more calcium, and
this water is referred to as “hard.” Conversely, water which passes through
rocks containing little or no calcium or magnesium, receives less of these
elements and is considered “soft.”

The type of rock is not the only factor which determines the hardness of
the water; pH is also important. Water that is acidic, or has a low pH, will
cause more calcium and magnesium to dissolve from the rock than water
with a high pH. Water which has been treated for home or industrial use
may be returned to the natural water supply with a different hardness level
than it originally had.

Water hardness is important to everyone, both homeowners and members
of industry. As soft water contacts surfaces containing calcium or
magnesium, such as plaster pool walls, it will remove these elements from
the surface. This is referred to as etching. Conversely, hard water will leave
calcium and magnesium deposits in pipes, boilers and equipment,
potentially causing clogs. These deposits are known as scale. In the home,
hard water reduces soap’s ability to lather, and may leave a film on clean
dishes and clothes.

Water can be treated to make it harder or softer. Calcium or magnesium,
often in the form of calcium chloride can be added to a water supply to
raise the hardness level. Water which is too hard can be treated using a
water softener, which removes calcium and magnesium so the water is
softer for use.

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TAKING WATER SAMPLES

There are many factors to consider before taking a water sample.

· The water sample should be representative of the source and free of
any foreign matter, such as aquatic plants and sediment from the
bottom.

· The container should be clean and free from particles. Use a plastic or
glass container with a screw cap that is large enough to hold water for
all desired tests.

· Unless the sample is to be tested immediately, the container should be
filled until it overflows, and then capped. This procedure eliminates
the possibility of getting air bubbles into the sample. A container
which is only half full with water is subject to chemical changes caused
by oxidation while transported. Generally, the less time between
collecting and analyzing the sample gives the best results.

· If the sample is taken from a tap, it is important to let the water run
for several minutes before the sample is taken.

WATER HARDNESS: METHOD I

1. Fill the test tube (0608) to the 20 mL line with sample water.

2. Add one Hardness T Tablet (6917). Shake until disintegrated. Sample

should turn red.

3. Continue adding Hardness T Tablets one at a time, shaking after each
tablet until the tablet disintegrates, and the red color changes to blue.
Count the number of tablets added.

NOTE: When counting tablets be sure to include the tablet used in
Step 2.

4. Use the following chart to determine hardness of sample.

# OF DEGREE
TABLETS OF HARDNESS RANGE

1 soft 20-100 ppm
2 hard 120-200 ppm
3 or more very hard over 200 ppm

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