Exp 10 Final Lab Report
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Transcript of Exp 10 Final Lab Report
The Wonder Liquid Water: Hard, Soft, or Softened
Alaina Weinheimer
November 6, 2012
CHEM 111, Section 105
Group Members: Kyle Turner, Roxanne Umali, and Casey Watson
TA: Matt Langston
Introduction:
The purity of water can be measured in a variety of ways. One way to measure the
amount of impurities in water is to measure the water’s hardness. The hardness of water is the
concentration of magnesium ions (Mg2+(aq)) and calcium ions (Ca2+
(aq)) in the water. Water
hardness results from the accumulation of these minerals in groundwater as the water passes
through rocks and soil that contain these compounds with these ions in them. The water
dissociates these compounds causing the hardness levels to increase1. Water hardness is
commonly measured in grains per gallon2.
Table 1. Concentration of Calcium ions and Magnesium ions Water Hardness Levels2
Concentration of Mg2+(aq) and Ca2+
(aq) (gpg) Hardness Level of Water
Less than 1.0 gpg2 Soft2
1.0 gpg – 3.5 gpg2 Slightly hard2
3.6 gpg – 10.5 gpg2 Hard2
Greater than 10.5 gpg2 Very hard2
Water hardness plays a large role industrial uses and cleanliness of items. Alone, Mg2+(aq)
and Ca2+(aq) in water do not cause sickness or ills to a consumer. Water hardness is problematic
in industrial uses and cleaning items because these ions often form insoluble compounds with
other elements leaving behind solid deposits. A common problematic compound that results
from the calcium ion is scale, CaCO3. Scale precipitates when the calcium ions in heated water
combine with bicarbonate ions2. The buildup of scale causes problems in dishwasher, pipe, and
heating system efficiency. In dishwashers, the solids accumulate on the dishes, making cleaning
the dishes more difficult. Scale buildup in pipes lessens the amount of water able to flow
through. Thus, pipes must be replaced every so often when the scale buildup becomes too
obstructive3. In industrial boilers, scale buildup reduces heat transfer2. This phenomenon has
caused heating bills to rise up to 25%. Despite these issues hard water causes, the calcium ions
and magnesium ions in hard water contribute, though minimally, to human daily nutrient intake3.
There are several ways to measure the hardness of water. Three ways include a chemical
indicator measurement , an instrument’s measurement, and a visual observation. The chemical
indicator method involves the addition of ethylenediaminetetraacetic acid (EDTA) as a
complexing agent and eriochrome black T (EBT) as the indicator. The equation for the addition
of these chemicals is below:
HD2- + Mg2+ + Ca2+ MgD- + H+ + Ca2+ CaEDTA + MgEDTA + HD2- Blue Red (immediately) (immediately) (last)
Blue
The addition of EBT turns the water sample solution a purple hue. EDTA is added to the
solution until the water returns to a blue color. The amount of EDTA added is proportional to
the hardness level of the water. The more EDTA needed to turn the water back to its original
color, the more divalent ions are in the water4. An instrument that can be used to determine the
hardness of water is an Atomic Absorption Spectroscope (AA). Sample water is sucked into the
instrument and held to an extremely hot flame. This causes the atoms in the water sample to be
separated. Meanwhile, a cathode lamp, which contains a source of light with a monochromatic
wavelength that corresponds to the subject element’s energy necessary to excite electrons to the
next energy levels, is emitted across the instrument. This wavelength of light is only absorbed
by that specific element in the atomized water sample because the energy of the wavelength only
corresponds to that elements energy necessary to excite an electron. As the light beam passes
through the sample, some of the light is absorbed and the rest of the light reaches a detector,
which measures the difference between the initial amount of light and the amount of light that
reached the detector. The amount of light absorbed is proportional to the concentration of the
EDTA
ion of interest. A calibration graph is made plotting known concentrations against absorbance
values. An unknown concentration of an ion can then be solved after its absorbance value is
measured by plugging that value into the calibration graph equation. In this experiment, a
wavelength for calcium ions was sent through in one instrument, and magnesium ions in another.
An additional method for measuring water hardness is the observation of total dissolved solids
(TDS). A portion of the water sample is evaporated, and the amount of residue left behind
indicates how impure the water is5. In summary, there are many ways to measure water
hardness.
The readings the two methods give differ slightly. The EDTA method tends to show
higher results of water hardness than the AA reads. The EDTA method indicates the
concentration of all divalent ions, more ions than calcium and magnesium ions. On the other
hand, the AA measures for the concentrations of magnesium ions and calcium ions specifically.
However, the AA reading is not completely accurate either. The AA that is being used may have
inherent instrument error. Check standards are run to measure this level of inherent error.
Known concentrations are run through the instrument to obtain a calibration curve. Then the
new samples of the same known concentrations, or check standards, are run through the
instrument again and solved for their concentration based on the new absorbance value using the
calibration curve equation4. In the instrument used in this experiment, there was some error. A
check standard for a concentration of 1ppm was ran through the instrument and came out to
1.27ppm6. The TDS observation does not lead to quantitative results and the solids in the residue
may be other precipitates than those formed by magnesium ions and calcium ions. In short, the
three methods of measuring water have their shortcomings, however, it is important to have to
methods to compare readings to and ensure reasonable results.
Softening techniques include the addition of the lime or washing soda to the water and
the ion exchange process. The chemical lime consists of calcium hydroxide. Calcium hydroxide
dissociates in water and then magnesium ions form a precipitate of Mg(OH)2(s). Washing soda
is sodium carbonate, which also dissociates in water. The carbonate forms a precipitate of
CaCO3(s). These solids are then filtered out of the water, resulting in water with lower
concentrations of magnesium ions and calcium ions2. In the ion exchange process, a resin, which
is a bead of polystyrene coated in monovalent ions, is added to a sample of water7. In this
experiment, the monovalent ion that coated the ion exchange resin was hydrogen ions. The
presence of hydrogen ions as the coating ions was discovered by a pH test of the solution that
remained after the ion exchange resin was added. All of the water samples displayed
acidity6,9,10,11. The divalent magnesium and calcium ions replaced the monovalent hydrogen ions,
on the resin, until the resin was saturated with magnesium and calcium ions, leaving the water
sample virtually free of magnesium and calcium ions7. In summary, two common methods of
softening water involve the addition of lime or washing soda to water and the ion exchange
process.
Regarding this experiment, many predictions can be made. In this experiment, sample of
water were taken from stream water from Roarin’ Spring in Blair County, PA; stream water from
Appalachian Springs in Blue Mountain, PA; pond water from the Alumni pond, and filtered
drinking water from an Atherton Hall water fountain. It is predicted that the water from Roarin’
Springs or Appalachian Springs will have the softest water of the samples because it comes from
a higher elevation than the other water sample sources. Water collects minerals that dissolve into
the water as the water flows over rocks and soil. The less rock and soil the water has passed
through, the less hard the water is7. Because the water from the springs originates from a higher
elevation than the other samples, it has travelled through less rocks and soil than the water in the
other samples has. Therefore, the springs water will be softer than the other two water samples.
These samples will leave less TDS behind when the sample is evaporated. It is expected that the
Alumni pond water will be the hardest because it is at the lowest elevation and has not been
processed at all, unlike the Atherton Hall water. The Alumni pond water will, predictably, have
the most TDS remaining when the sample is evaporated. Regarding the water softening tests, it
is expected that the springs waters will still be less hard than the other two water samples
because the other two samples have a higher hardness initially. In short, it is predicted that the
springs water samples will be softer than the other two water samples, and will remain softer
even after water softening processes have been carried out.
Procedure:
This experiment was carried out according to the steps within the PSU Chemtrek4. The
water samples were measured for hardness using the AA first. A large pipette was filled with
some of the water, and a diluted sample was prepared by adding 5mL of distilled to 5mL of
sample water in a graduated cylinder. A large pipette was filled with this water. The diluted
sample was prepared in case the concentration of either of the ions was too high for the AA to
read. These samples were then taken to the AAs. The first AA measured calcium ion
concentration and the second AA measured magnesium ion concentration. Prior to the use of the
AAs, the AAs were calibrated.
Next, the samples were tested for hardness by seeing how many total dissolved solids
(TDS) the samples contained. Water sample drops were placed on individual pieces of
aluminum foil, along with a drop of distilled water and a calcium ion solution for comparison4.
Measuring the water hardness by the EDTA method involved a serial dilution of EDTA.
The number of drops of EDTA required to turn the purple water blue corresponded to the
concentration of divalent ions in the water4.
Next, the water samples tested for the ability to soften with two techniques. A
commercial water-conditioning agent was added to the water sample. Then that solution was
tested for hardness via the EDTA serial dilution test. The next softening technique used was the
ion exchange resin. An ion exchange resin was added to the water sample. Then the water
sample was tested for harness, using the EDTA serial dilution test. Once these tests were
completed, calculations were made to find the hardness of the water4.
Results:
Atomic Absorption Spectroscopy Data
Table 1. Calibration of Calcium Ion Concentration in the AA6.
Caption: This table shows the absorbance values of the different known concentrations of
calcium ions and the check standards. The values of the calcium ion concentrations and
absorbances in this table are used to create a calibration curve seen in Graph 14. The check
standards show the level of error in the instrument. The instrument has higher error in low
concentration values and less error in higher concentration values6.
Calcium ion Concentration Standard Check
0
1 0.01082 1.27
5 0.05310 5.09
10 0.10000 9.81
25 0.23103 24.08
50 0.43298 50.45
Graph 1. Calcium ion Absorbance Values vs. Calcium ion Concentration6
Caption: The known calcium ion concentrations from Table 2 were plotted against their
respective absorbance values from Table 2 to find a line of best fit. This line of best fit equation
allows concentrations of calcium ions to be calculated based on the absorbance reading from the
AA4. The trendline equation in this graph is y = 0.0085x + 0.016.
0 10 20 30 40 50 600
0.10.20.30.40.5
f(x) = 0.00854824680210685 x + 0.0100079082016554R² = 0.998684146580191
Absorption Value vs. Calcium Concentration
Concentration (ppm)
Abso
rptio
n Va
lue
Table 2. Calibration of Magnesium Ion Concentration in the AA6
Caption: This table shows the absorbance values of the different known concentrations of
magnesium ions and the check standards. The values of the magnesium ion concentrations and
absorbances in this table are used to create a calibration curve seen in Graph 14. The check
standards show the level of error in the instrument. The instrument has higher error in low
concentration values and less error in higher concentration values6.
Magnesium ion Concentration Standard Check
0
1 0.01517 1.48
5 0.08718 5.62
10 0.18376 10.53
25 0.39579 24.72
30 0.48868 29.02
Graph 2. Magnesium ion Absorption Values vs. Magnesium ion Concentration6
Caption: The known magnesium ion concentrations from Table 2 were plotted against their
respective absorbance values from Table 2 to find a line of best fit. This trendline allows
concentration of magnesium ions to be calculated from the absorbance reading from the AA4.
The line of best fit equation in this calibration graph is y = 0.0159x + 0.00836.
0 5 10 15 20 25 30 350
0.10.20.30.40.50.6
f(x) = 0.0159016552582452 x + 0.00831249533291845R² = 0.997150551449768
Absobrance Value vs. Magnesium Concentration (ppm)
Concentration (ppm)
Abso
rban
ce V
alue
Table 3. Concentration of Calcium ions and Magnesium ion in Samples Measured by the AA
Caption: Table 3 displays the calcium ion and magnesium ion concentrations of each water
sample measured by the AA and calculated using the equations from the graphs of the
corresponding ion.
Calculation: Ion Concentration from Absorbance Value4
The concentration of calcium ions and magnesium ions in water samples were calculated
plugging the absorbance reading from the AA in the calibration graph equation from Graph 1
and Graph 2 for the respective ions.
Example calculation of ion concentration6:
Absorbance value of calcium from the Atherton Hall water sample: 0.4216
y is the absorbance value that the AA measured. x is the concentration that is being solved for.
y = 0.0085x + 0.01
In this example calculation, the absorbance value (y) being used is 0.4216.
0.4216 = 0.0085x + 0.01
Algebraic manipulation is used to isolate the x value by subtracting the 0.01 from 0.4216 and
dividing that value by the slope of the trendline of 0.0085. Because x represents the ion
concentration, the value x equals, once x is isolated using the trendline equation, is the ion
concentration.
0.4116 = 0.0085x
48.42ppm = x
Calculation: Concentration of Diluted Sample6
The diluted water sample contains half of the original concentration of the water sample. In this
experiment, the only water sample that was diluted in order for the AA to be able to read the
absorbance value was in the magnesium ion sample of the Atherton Hall water. In order to
calculate to the undiluted concentration, the concentration that the calibration graph read in the
diluted sample must be doubled, because this concentration represents only half of the original
concentration.
16.67ppm = ½ Magnesium ions concentration in the Atherton Hall water sample
33.35ppm = Magnesium ion concentration in the Atherton Hall water sample
Calculation: Total Hardness of Water
Calcium ion concentration (ppm) + Magnesium ion concentration (ppm) = Hardness (ppm)
48.42ppm + 33.35ppm = 81.77ppm
SampleAtherton
Hall6Roarin’ Springs9
Alumni Pond10
Appalachian Springs11
Absorbance in Calcium
ion0.4216 0.2720 0.3073 0.3281
Calcium ion concentration
48.42ppm 30.82ppm 34.98ppm 37.42ppm
Absorbance in Magnesium
ion
0.2734 (diluted)
0.1258 0.4012 0.3281
Magnesium ion
concentration33.35ppm 7.390ppm 24.71ppm 18.15ppm
Hardness in ppm
81.77ppm 38.21ppm 59.69ppm 55.57ppm
Table 4. Water Hardness in of Samples Determined by the EDTA Serial Dilution
Caption: This table shows the hardness of the water samples based on the EDTA serial dilution.
Calculation: Hardness in ppm by EDTA Serial Dilution
To find the concentration of calcium ions and magnesium ions in the water samples based on the
amount of EDTA added to the water sample, the molarity and volume of the EDTA were set
equal to the molarity and volume of the calcium and magnesium ions since the amount of EDTA
added is proportional to the ions concentration. The molarity of the EDTA was known to be 2.0
X 10-4M. The volume of the EDTA is the number of drops added to the water sample. Only one
drop of water sample was in each well. The unknown variable, then, is the molarity of calcium
ions and magnesium ions in the water. Algebraic manipulation is then used to find the molarity,
by dividing the product of the EDTA molarity and volume by the 1 drop of sample water.
MEDTAVEDTA = MCa2+
Mg2+ V Ca
2+Mg
2+ 4
Molarity EDTA = 2.0 X 10-4 M
Volume of EDTA = number of drops added to well
Volume of Calcium ions and Magnesium ions: 1 drop
Example: Atherton Hall water sample6
(2.0 X 10-4M)(12 drops EDTA) = MCa2+
Mg2+(1 drop water sample)
2.4 X 10-3Mdrops = MCa2+
Mg2+(1 drop water sample)
2.4 X 10-3M = MCa2+
Mg2+
Calculation: Convert Molarity to ppm4
Water hardness is often measured in the amount of calcium carbonate (CaCO3(s)) in the solution
necessary to have the same results as the EDTA titration. In this case, the moles in the molarity
of the water sample are converted to grams of CaCO3(s) using the molar mass of CaCO3(s).
Those grams are then converted to milligrams to result in parts per million (ppm)4.
Example Calculation6:
MCa2+
Mg2+ X the grams in one mole of CaCO3(s) X the number of milligrams in one gram = ppm
MCa2+
Mg2+ = 2.4 X 10-3M
2.4 X 10-3M X 100 g CaCO 31 molCaCO 3
X 1000mg
1 g= 240ppm
Sample Atherton Hall8 Roarin’ Springs9 Alumni Pond10 Appalachian Springs11
# of EDTA drops 12 6 50 9Hardness 240ppm 120ppm 1000ppm 180ppm
Table 5. Comparison of Hardness Results from the Three Techniques in the Water Samples
This table shows the difference in hardness levels that each method gave.
HardnessMeasurement
TechniqueSample
Atherton Hall8 Roarin’
Springs9Alumni Pond10
Appalachian Springs11
AA reading 81.77ppm 38.21ppm 59.69ppm 55.57ppmEDTA titration
240ppm 120ppm 1000ppm 180ppm
TDS Observation
Faint thin white ring
Distinct thin ring
Distinct thick ring
Thick white ring
Table 6. Hardness of Water Samples after Application of Water Softener Techniques Calculation: Hardness of Water in ppm after Water Softeners Added
After the water softeners were added, an EDTA titration followed to find the hardness of the
water samples. The calculation for this is the same as the calculations done for the hardness of
water in Table 4.
Water Softening Technique
Name and Sample
Alaina Atherton
Hall8
KyleRoarin’ Springs9
RoxanneAlumni Pond10
CaseyAppalachian
Springs11
Baking Soda Addition
Drops EDTA added
12 6 12 9
Hardness ppm
240ppm 120ppm 240ppm 180ppm
Resin Addition
Drops EDTA added
3 1 5 1
Hardness ppm
60ppm 10ppm 100ppm 10ppm
Discussion:
Overall, the results show that none of the water samples are considered very hard. The
water samples all have hardness levels below 5.0 grains per gallon, the equivalent of 85.5ppm,
using the values given in the AA readings, which is considered very hard2. On the whole, the
hardness levels of the different water samples resulted as predicted. The water from the springs
had the lowest levels of hardness. Roarin’ Springs water had the lowest hardness of 38.21ppm,
given by the AA reading, and Appalachian Springs water was on the lower half with a hardness
level of 55.57ppm, from the AA reading6. The highest hardness level was found in the Atherton
Hall water, with a hardness of 81.77ppm, from the AA reading, while the Alumni pond water
had a lower hardness level of 59.69ppm, from the AA reading6. In short, the water samples had
hardness levels from the AA readings that matched the hypothesis.
The EDTA measurement gave very different results. As expected, the EDTA titration
analysis of the water samples’ hardness did exceed the AA analysis, because the EDTA titration
measures the concentration of all of the divalent ions in the water, not just calcium ions and
magnesium ions as the AA does, making the AA reading more accurate than the EDTA
measurement in regards to water hardness. For instance, in the Atherton Hall water, the EDTA
titration reading of hardness of 240ppm, was roughly triple that of the AA reading of 81.77ppm.
This significant difference in EDTA titration hardness readings and AA hardness readings may
explain why the Alumni pond water had a lower hardness level of 55.57ppm than the Atherton
Hall water 81.77ppm of according to the AA reading, and a hardness level, 1000ppm,
significantly higher than that of the Atherton Hall water, 240ppm, according to the EDTA
titration. The Alumni pond must contain additional polyvalent ions that the Atherton Hall water
does not contain in order for the EDTA reading to be higher in the Alumni pond water while
having a lower hardness level in the AA reading. In short, the EDTA measurements are less
accurate than the AA readings.
The TDS observation displayed results that conflicted with the other hardness reading
methods. It appeared as though Appalachian spring water had the most total dissolved solids left
after the water had evaporated even though the Appalachian spring water had a relatively low
water hardness level of 59.69ppm. Meanwhile, the water sample with the highest hardness level
of 81.77ppm had the least total dissolved solids. In short, apart from the TDS test, the hardness
levels of water in the water samples followed the hypothesis that the springs waters would have
lower hardness levels.
After water softeners were added to the water samples, similar pattern was seen. The
lowest hardness levels were in the springs water and the higher levels were in the other two
samples. As seen in Table 6, for the most part, the addition of the washing soda to the water
samples did not decrease the hardness of the water samples. Only in the Alumni pond water and
the Appalachian springs water did the hardness level decrease. However, as seen in Table 6, the
ion exchange softening method caused water hardness levels to decrease dramatically across the
board. For instance, after the ion resin was added to the Atherton Hall water decrease from a
hardness of 240ppm to 60ppm, one-fourth of the original hardness. Generally speaking, the ion
exchange resin is a more effective water softener than the commercial water softening agent.
Throughout the experiment, there was plenty of room for error. To start, the AA
instrument did not give completely accurate results. As seen in Table 1 and Table 2, the check
standards deviated from the original concentrations. The original known concentrations were
even concentrations of 1ppm, 5ppm, etc. They were run through the AA to find their absorbance
values. The absorbance values were then plotted against the known concentrations to make a
best fit line equation that could be used to find unknown concentrations based on absorbance
values. When new samples of the same known concentrations, such as 1ppm, were run through
the AA, the AA read different absorbance values, causing the concentration calculated based on
the best fit line to not result in the same concentration, calculating to 1.27ppm instead of 1ppm in
the calcium ions check standards. Lower known concentrations resulted in greater deviancies
from the actual concentration. For instance, the calcium ion check standard for 1ppm was
1.27ppm, almost a 1/3 of a difference, while the calcium ion check standard for 50ppm was
50.45ppm, a 0.9% deviance6. The EDTA titration had ample room for error. When adding
EDTA to the water sample solutions in the serial dilution, being one well off in determining
which well shows the endpoint is a difference of 20ppm. The TDS observation has similar error
factors as the EDTA, regarding a qualitative analysis. The TDS remaining on the aluminum foil
may have appeared different to different eyes in the group. Also, as stated previously, the drop
used to measure the TDS may have had a concentration of dissolved solids that misrepresents the
entire what sample since the solution is not completely homogeneous. In all, there is ample
room for experimental and human error in this experiment.
Overall, the water hardness of each water sample was under or matched typical levels.
The Atherton Hall water fountain water had a lower hardness level of 81.77ppm compared to
average State College water of 120ppm-190ppm. Similarly, the Alumni Pond water, which is
also in State College, had a hardness level of 59.69ppm, also within the State College water
range of 120ppm-190ppm12. The spring water sample from Roarin’ springs had a water hardness
level of 38.21ppm within the average range of Blair County’s water of 34ppm-85ppm13. The
spring water sample from Appalachian springs had a hardness level of 55.57ppm, within the
typical range of Blue Mountain area’s water hardness levels of 5ppm-88ppm14. On the whole,
the water hardness levels of each water sample either were under or matched typical levels.
Conclusion:
This experiment revealed the hardness of different water samples using different
techniques, as well as tested the effectiveness of water softening techniques. The techniques to
measure water hardness included AA, EDTA titration, and TDS observation. The water
softening techniques included adding a washing soda to the water samples and the ion exchange
process. The results of the experiment coincided with the hypotheses. The spring waters did
have the lower levels of hardness. In Roarin’ Springs, the water hardness, according to the AA
reading, was 38.21ppm. The water hardness in the Appalachian Springs was 55.57ppm. Both of
these values are higher than the hardness of the Alumni pond water, 59.69ppm, and the Atherton
Hall water, 81.77ppm. The EDTA titration readings were higher than the AA readings, as
expected. Overall, the experiment met predictions.
References:
(Print sources are bolded.)
1. "Hard Water." The Water Quality Association. Water Quality Association. Web. 1 Nov
2012. <http://www.wqa.org/sitelogic.cfm?ID=207>.
2. Casiday, Rachel, and Regina Frey. "Water Hardness." The Department of Chemistry,
Washington University. Washington University, n.d. Web. 1 Nov 2012.
<http://www.chemistry.wustl.edu/~edudev/LabTutorials/Water/FreshWater/hardn
ess.html>.
3. . "Hard Water Problems." Hard Water.org.uk. Guides Network. Web. 1 Nov 2012.
<http://www.hardwater.org/hard_water_problems.html>.
4. Keiser, Joseph. PSU ChemTREK. Hayden McNeil. (2012-2013): 10-1 – 10-22.
5. Campbell, Jarryd, and Dan Peterson. "Concordia College Journal of Analytical
Chemistry ." Concordia College Journal of Analytical Chemistry . 1. (2010): 4-
8. Web. 1 Nov. 2012.
6. Weinheimer, Alaina. Chemistry 111 Notebook.
7. Skipton, Sharon O., Bruce I. Dvorak, and Shirley M. Niemeyer. "NEB Guide." NEB
Guide. (2008): n. page. Web. 5 Nov. 2012.*
8. "Hardness in Drinking Water." wellcare. Water Systems Council. Web. 6 Nov 2012.
<http://www.watersystemscouncil.org/VAiWebDocs/WSCDocs/1683274HARD
NESS.PDF>.
9. Turner, Kyle. Chemistry 111 Laboratory Notebook.
10. Umali, Roxanne. Chemistry 111 Laboratory Notebook.
11. Watson, Casey. Chemistry 111 Laboratory Notebook.
12. . "FAQ." State College Borough Water Authority. State College Borough Water
Authority. Web. 13 Nov 2012. <http://www.scbwa.org/pages/faq>.
13. "Frequently Asked Questions." Altoona Water Authority. Altoona Water Authority. Web.
13 Nov 2012. <http://www.altoonawater.com/index.php?page=faq>.
14. "Typical Water Quality Information: Blue Mountain System." Pennsylvania American
Water. Pennsylvania American Water. Web. 13 Nov 2012.
<http://www.amwater.com/paaw/customer-service/water-quality-reports.html>.
* This source was a brochure I viewed online. The page numbers were not on the brochure. It
was from the University of Nebraska’s website.