PART 3 Water Sample Analysis Lab Date: Due Date: Background...

Name:__________________________ Chemistry In the Environment - ISU

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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.


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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)


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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?


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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


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)


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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.


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


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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



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Sample

#

Date

Sampled

Time

Sampled

Specific

Location

Results after 2

drops of

Phenolphthalein

Amount of

Carbon Dioxide

(ppm)


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


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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


11. Compare your sample with that of 2 other students


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Sample

#

Date

Sampled

Time

Sampled Specific Location Nitrate (ppm)


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?


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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




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Sample

#

Date

Sampled

Time

Sampled Specific Location Phosphate (ppm)


12. Explain which of these samples is the safest/least safest to drink and why.


14. Hypothesis as to where the phosphates have come from for the samples you have

collected?


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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





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Sample

#

Date

Sampled

Time

Sampled

Specific

Location Results of Testing


15. Why did you choose this sample for this test?


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?


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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




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

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