part 3 water sample analysis lab date: due date: background...
TRANSCRIPT
Name:__________________________ Chemistry In the Environment - ISU
P a g e | 1
PART 3 – Water Sample Analysis Lab Date: ____________________ Due Date: ___________________
Background
Using the samples that you have collected you will perform several water quality
tests in order to compare the different samples and determine whether they are safe
for consumption. Based on the background information obtained in PART 1, you will
now perform water quality tests that are necessary to analyze the quality of the water.
Task
You will be performing the same test on each of the water samples that you have
collected.
□ Acidity Test
□ General Water Hardness
□ Carbon Dioxide Test
□ Nitrate Test
□ Phosphate Test
□ Coliform Test
Before you begin, layout all of your 10 water samples out in a tray (make sure they
are labelled (Sample #1 Sample #10). Remember that your samples are your own,
and thus your water tests must be done individually. Remember to follow the all of the
proper procedures for each test. The key to these experiments is accurate and detailed
observations, as well as staying organized throughout.
Name:__________________________ Chemistry In the Environment - ISU
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Procedure #1
TEST NAME: Acidity Test
Background
At 25° C the pH of pure water is very close to 7. Acids have a pH
less than 7 while bases have a pH greater than 7. Because it has a
pH of 7, water is considered to be neutral. It is neither an acid nor a
base, but is the reference point for acids and bases. Although the pH
of pure water is 7, drinking water and natural water exhibits a pH
range because it contains dissolved minerals and gases. Surface
waters typically range from pH 6.5 to 8.5 while groundwater ranges
from pH 6 to 8.5.
Water with a pH less than 6.5 is considered acidic. This water
typically is corrosive and soft. It may contain metal ions, such as
copper, iron, lead, manganese and zinc. The metal ions may be toxic,
may produce a metallic taste, and can stain fixtures and fabrics. The
low pH can damage metal pipes and fixtures.
Water with a pH higher than 8.5 is considered basic or alkaline. This
water often is hard water, containing ions that can form scale
deposits in pipes and contribute an alkali taste.
Materials
□ pH paper ( x 10) □ Water Samples
# (1-10)
□ Eye Droppers
(x 10)
□ pH colour scheme
Procedure
1. Obtain 10 different strips of pH paper
2. Using a water dropper, place one drop of water from
Sample #1 onto the pH paper
3. Based on the colour scheme provided, record the pH value
4. Repeat the pH test for each Sample #2-10, making sure to
use a clean, dry dropper for each test
5. Record your observations in the table below.
6. Rinse and dry all materials, and dispose as instructed
(Note: All tables/discussions questions must be typed and be part of the ongoing ISU package)
Name:__________________________ Chemistry In the Environment - ISU
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Observation Table (rough notes)
Sample
#
Date
Sampled
Time
Sampled Specific Location
pH paper
colour pH value
1
2
3
4
5
6
7
8
9
10
Discussion Questions
1. Were there any samples that were not neutral Where were they sampled from?
2. According to the pH tests, which of these samples is the least/most safest to drink
and why?
Name:__________________________ Chemistry In the Environment - ISU
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Procedure #2
TEST NAME: General Water Hardness
Background
Hard water is water that has high mineral content, such as calcium
and magnesium ions. Hard water is not a health risk, but a nuisance
because of mineral buildup on fixtures and poor soap and/or
detergent performance. As water moves through soil and rock, it
dissolves very small amounts of minerals and holds them in
solution. Calcium and magnesium dissolved in water are the two
most common minerals that make water “hard.” The degree of
hardness becomes greater as the calcium and magnesium content
increases.
Materials
□ 10 mL graduated
cylinder ( x 10)
□ Water Samples #
(1-10) □ Syringe
□ Vial with lid ( x 10) □ Soap Reagent □
Procedure
1. Measure out 5 mL of Sample #1 into the graduated cylinder
2. Carefully add one drop of the Soap Reagent to the sample
using the syringe
3. Place this sample into a vial, seal it and shake vigorously
4. Did lather form on the surface (soap bubbles)? If not,
continue adding one drop at a time and vigorously shaking
after each drop. Keep track of the number of drops
5. Record the number of drops it takes to produce a permanent
lather on the surface. Compare with the table below for a
description of your sample
6. Record all of your observations in the table below.
7. Repeat the above steps for Samples #2-10, making sure to
use a different graduated cylinder and vial for each test
8. Rinse and dry all materials, and dispose as instructed
Water Hardness Classification Table
Number of Drops Description Number of Drops Description
1-4 drops Soft Water 9-12 Hard
5-8 drops Moderately Hard > 12 drops Very Hard Note: All tables/discussions questions must be typed and be part of the ongoing ISU package)
Name:__________________________ Chemistry In the Environment - ISU
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Observation Table (rough notes)
Sample
#
Date
Sampled
Time
Sampled
Specific
Location
# of Drops to
Produce Lather
Type of
Hardness
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Discussion Questions
3. Explain which of these samples is the safest to drink and why.
4. Explain which of these samples is the least safest to drink and why.
5. Prepare a new table/list organizing the water samples from soft – hard
Name:__________________________ Chemistry In the Environment - ISU
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Procedure #3
TEST NAME: Carbon Dioxide Test
Background
Carbon Dioxide is present in water in the form of a dissolved gas.
Surface waters normally contain less than 10 ppm free carbon
dioxide, while some ground waters may easily exceed that
concentration.
Aquatic plant life depends upon carbon dioxide and
bicarbonates in water for growth. Microscopic plant life suspended
in the water, phytoplankton, as well as large rooted plants, utilize
carbon dioxide in the photosynthesis of plant materials; starches,
sugars, oils, proteins. The carbon in all these materials comes from
the carbon dioxide in water.
Materials
□ Carbon Dioxide
Reagent □ Phenolphthalein
□ Test tube
(x 10)
□ 25 mL graduated
cylinder ( x 10)
□ Water Samples
(choose only 5) □ Syringe
□ Test tube rack
Procedure
1) Fill the graduated cylinder with 20 mL of Sample #1
2) Dispense this solution into the test tube
3) Add 2 drops of phenolphthalein and then swirl. If the sample
turns red, then no free carbon dioxide is present. If sample is
colourless, continue with step 3
4) Insert the syringe into top of the Carbon Dioxide Reagent bottle.
Flip the bottle upside down and withdraw the liquid to the zero
mark on the syringe. Ensure there are no air bubbles.
5) While gently swirling the tube, add Carbon Dioxide Reagent one
drop at a time, until a very faint pink color is produced and
persists for 30 seconds. (make sure to stop when it remains)
6) Record the reading on the syringe once the solution remains
pink. This will be the reading of ppm of Carbon Dioxide
7) Record in the observation table below.
8) Repeat for five other Samples, using a different graduated
cylinder and test tube for each.
9) Rinse and dry all materials, and dispose as instructed
(Note: All tables/discussions questions must be typed and be part of the ongoing ISU package)
Name:__________________________ Chemistry In the Environment - ISU
P a g e | 7
Observation Table (rough notes)
Sample
#
Date
Sampled
Time
Sampled
Specific
Location
Results after 2
drops of
Phenolphthalein
Amount of
Carbon Dioxide
(ppm)
Discussion Questions
6. Explain which of these samples has the highest CO2 content and why?
7. Explain which of these samples has the lowest CO2 content and why?
8. Prepare a new table/list organizing the water samples from highest-lowest
Name:__________________________ Chemistry In the Environment - ISU
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Procedure #4
TEST NAME: Nitrate Test
Background
Nitrate is one of the most common groundwater contaminants
in rural areas. It occurs naturally in soil and water as a result of
decaying plants and animal residues. Other common sources of
nitrate include human sewage and livestock manure. Nitrate is also
a common constituent of chemical fertilizers.
Nitrate in ground water can be derived from natural sources or
from point sources, such as sewage disposal systems and livestock
facilities. Surface water runoff from fertilized farmland and animal
feedlots is a major potential source of nitrate contamination
Nitrate occurs naturally in groundwater, usually at
concentrations far below a level of concern for drinking water
safety. However, nitrate in water is not easily noticed since it is
colourless, odourless and tasteless. Only water testing can
determine nitrate concentration in your drinking water supply.
Materials
□ Mixed Acid Reagent
in dropper bottle
□ Water Samples
(choose two) □ Eye Dropper
□ Nitrate Reducing
Agent and spoon □ Vial and cap
□ Standard
Solutions
Procedure
1. Using an eyedropper, fill the vial up to the first mark with the
water sample.
2. Using the Mixed Acid Reagent in dropper bottle, fill up to the
second mark. Cap the solution and mix well.
3. Wait two minutes before proceeding to the next step.
4. Using a small spoon, scoop one level measure (avoid any
excess) of Nitrate Reducing Agent and add to the vial
5. Cap the vial and invert 50-60 times.
6. Wait 10 minutes. Mix once more
7. Compare the samples with the standard solutions by inserting
the vial into the empty slot
8. Record the Nitrates in ppm in the observation table below.
9. Repeat the above steps for one other sample
10. Rinse and dry all materials, and dispose as instructed
11. Compare your sample with that of 2 other students
Name:__________________________ Chemistry In the Environment - ISU
P a g e | 9
(Note: All tables/discussions questions must be typed and be part of the ongoing ISU package)
Observation Table (rough notes)
Sample
#
Date
Sampled
Time
Sampled Specific Location Nitrate (ppm)
Discussion Questions
9. Explain which of these samples is the safest/least safest to drink and why.
10. How did the results of your sample compare with the other 2 students?
11. Hypothesis as to where the nitrates have come from for the samples you have
collected?
Name:__________________________ Chemistry In the Environment - ISU
P a g e | 10
Procedure #5
TEST NAME: Phosphate Test
Background
Phosphates are chemical compounds containing phosphorus.
Phosphorus is a non-metallic element which is necessary for life and
is found in rock as inorganic phosphates. As water runs over and
through rocks it carries off small amounts of minerals such as
calcium, magnesium, and phosphates. Inorganic phosphates are a
plant nutrient and are taken in by plants with water and incorporated
into organic phosphate compounds. Natural waters have a
phosphorus concentration of approximately 0.02 parts per million
(ppm) which is a limiting factor for plant growth. On the other hand,
large concentrations of this nutrient can accelerate plant growth.
The addition of large quantities of phosphates to waterways
accelerates algae and plant growth in natural waters; enhancing
eutrophication and depleting the water body of oxygen. Manmade
sources of phosphate include human sewage, agricultural run-off
from crops, sewage from animal feedlots, pulp and paper industry,
vegetable and fruit processing, chemical and fertilizer manufacturing,
and detergents.
Materials
□ Water Samples
(choose 3)
□ 1.0 mL pipet and
Plain pipette
□ Phosphate
Reagent
□ Vial with cap □ Reducing Reagent □ Standard
Solutions
Procedure
1. Fill the vial to the mark with the water sample
2. Using the 1.0 mL pipette (fill to mark), add 1.0 mL of
Phosphate Reagent to the vial sample, stopper, and mix by
inverting the vial several times
3. Wait for 5 minutes, then use the plain pipette to add three
drops of Reducing Reagent.
4. Cap and mix. Colour will develop in 10 seconds
5. Insert the test tube to be compared against the standard
solutions. Record in the observations below.
6. Wash out the test tube with water only, and dry.
7. Repeat the above steps for the other two samples
8. Rinse and dry all materials, and dispose as instructed
9. Compare your sample with that of 2 other students
Name:__________________________ Chemistry In the Environment - ISU
P a g e | 11
(Note: All tables/discussions questions must be typed and be part of the ongoing ISU package)
Observation Table (rough notes)
Sample
#
Date
Sampled
Time
Sampled Specific Location Phosphate (ppm)
Discussion Questions
12. Explain which of these samples is the safest/least safest to drink and why.
13. How did the results of your sample compare with the other 2 students?
14. Hypothesis as to where the phosphates have come from for the samples you have
collected?
Name:__________________________ Chemistry In the Environment - ISU
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Procedure #6
TEST NAME: Coliform Test
Background
Coliforms are bacteria that are always present in the digestive
tracts of animals, including humans, and are found in their wastes.
Water pollution caused by fecal contamination is a serious problem
due to the potential for contracting diseases from pathogens.
Testing for coliform bacteria can be a reasonable indication of
whether other pathogenic bacteria are present. Testing for bacteria
is the only reliable way to know if your water is safe. You cannot tell
by the look, taste, or smell of the water if disease-causing organisms
are in it. If coliform bacteria are present in your drinking water,
your risk of contracting a water-borne illness is increased.
Materials
□ 10 mL graduated
cylinder □ Eye dropper
□ Water Sample
(choose 1)
□ Coliform Test
solution
Procedure
1. Choose only one of your samples, that you are interested in,
based on the description above.
2. Pour approximately 5 mL of your water sample into the
graduated cylinder.
3. Using a dropper, measure 40 drops of your sample and
remove the cap of the Coliform Test solution and add.
4. Keep the small vial in a warm area for 24 – 48 hours
5. If after 48 hours the solution is still purple, coliforms are not
present. If after 48 hours, the solution is green or yellow,
then coliforms are present and this would indicate that
human waste from the intestinal tract has been emptied in
the water’s source
6. Compare your sample with that of 2 other students
7. Rinse and dry all materials, and dispose as instructed
(Note: All tables/discussions questions must be typed and be part of the ongoing ISU package)
Name:__________________________ Chemistry In the Environment - ISU
P a g e | 13
Observation Table (rough notes)
Sample
#
Date
Sampled
Time
Sampled
Specific
Location Results of Testing
Discussion Questions
15. Why did you choose this sample for this test?
16. How did the results of your sample compare with the other 2 students?
17. According to the end of the procedure, “if the test is negative, it does not mean that
water is safe.” Discuss why this statement is included
Conclusion Questions
1. In a few paragraphs, summarize your findings from these experiments. Make sure to
answer the following using evidence to support your statements
a. Which sample is the safest to drink overall?
b. Which sample is the least safest to drink overall?
c. Why is it important to conduct different types of tests on the same water
sample?
d. What were some of the sources of error through these experiments? Be
specific
e. What have you learned overall from Part 2 and Part 3 of the ISU?
Name:__________________________ Chemistry In the Environment - ISU
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Marking Scheme (updated)
PART Category Task Mark Out of
1 KU
Answers to questions on page 279 (# 1-8, 10)
20
Answers to questions on page 284 (# 1-5)
10
2
TI
10 samples collected by due date
10
Samples have been collected in a variety of different locations
5
Samples have accurately labelled and documented
5
C
Discussion Question #1
2
Discussion Question #2
2
3
TI
Water Sample Testing – Performance During the Lab (level)
4
Water Sample Testing – Detailed Observations recorded for
each test (completed and descriptive observation tables) 31
C Discussion Question #1 -17
34
Conclusion Questions 10
4
A Lead Water Testing from School data – Table
40
C
Discussion Question # 6 2
Discussion Question # 7 1
Discussion Question # 8 1
Discussion Question # 9 2
5
A Part A – Recorded Standards
4
C
Part A – Question: What do you notice about the standards from
each country
2
Part A – Questions (a –c) 6
Part B - Questions (a –d) 8
References (minimum 3 and properly formatted) 4
KU: ____/ 30 TI : _____/ 55
C: ____/ 74 A: _____ / 44