BASIC WATER QUALITY

CHE 331 CHEMICAL ENGINEERING LABORATORY

Instructor : Mrs. Noorzalila Binti Muhammad Niza

Group : 1

Team : 8

Planner : Anees Nurzalikha binti zakarya 2011682152

Experimenter : Anis Haziqah binti Ahmad Halil 2011294198

Analyzer : Muhammad Shamier bin Ameerdeen 2011848024

Consultant : Muhammad Razif bin Saidina Omar 2011464104

Date of experiment performed : May 22 , 2013

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ABSTRACT

The experiment was conducted to investigate the amount of carbon dioxide in sample

of water, the amount of dissolved oxygen in water sample using 300 ml BOD bottle, and the

temperature and pH of water sample. In experiment 1, the sample volume and titration

cartridge was selected from Table 1. Drain water was used as the water sample and was

collected in titration flask. Then one Phenolphthalein Indicator Powder Pillow was added.

Sodium Hydroxide Titration Cartridge was added into the solution until the colour changes to

light pink colour. For experiment 2, the water sample was collected. One Manganous

Sulphate Powder and one Alkaline Iodide-Azide Reagent Powder Pillow were added. An

orange-brown flocculent precipitate will formed. One Sulfamic Acid Powder Pillow was

added and a sample volume and Sodium Thiosulfate Titration Cartridge was selected from

Table 2. The sodium thiosulfate was added until the solution turn to a pale yellow colour.

Starch Indicator Solution was added and dark blue colour developed. This process was

continued until colourless solution formed. For experiment 3, by using the apparatus

provided, the temperature and the pH of the water sample was recorded. Experiment 1, 2, and

3 was repeated by using carbon dioxide rich water.

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For the experiment using drain water, the amount of carbon dioxide and oxygen were

35.7 and 5.5. The temperature to test the amount of carbon dioxide and dissolved oxygen

were both 28.2 ºC while the pHs were 7.04 and 7.06. For the experiment using carbon

dioxide rich water, the amount of carbon dioxide and oxygen were 80 and 8.3. The

temperature to test the amount of carbon dioxide and dissolved oxygen was 26.2 ºC and 26.1

ºC while the pHs were 7.27 and 7.13. The amounts of carbon dioxide in both water samples

were higher than the amount of oxygen. The temperature and the pH values in both water

samples were around the average value which were 27 ºC and 7.13. The higher the number of

digits, the higher the concentration of carbon dioxide and oxygen in the water sample. The

concentration of carbon dioxide and oxygen in the water sample depends on the source of

water itself.

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Table of Contents

Abstract…………………………………………………………………………………….. 2

Table of contents…………………………………………………………………………… 4

Introduction………………………………………………………………………………... 5

Objective………………………………………………………………………………….... 6

Theory……………………………………………………………………………………… 7

Description of Apparatus……………………………………………………………….… 8

Experimental Procedures………………………………………………………………… 10

Result……………………………………………………………………………………… 14

Calculated Data Tables……………………………………………………………………14

Final Data and Results…………………………………………………………………… 15

Discussion of Results……………………………………………………………………... 16

Conclusion and Recommendation………………………………………………………. 18

References………………………………………………………………………………… 21

Appendices

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INTRODUCTION

Water quality is determined by a few factors, such as the concentration of dissolved

oxygen, bacteria levels, the salinity or the amount of turbidity. It is not an easy thing to say

that the water is good either bad. In order to determine it, the quality of water has to be tested

first. This is because the poor water quality can pose a health risk for people and can also

cause many risk to ecosystem quality. Beside, other common measurement also taken to

define the quality of water such as dissolved oxygen (DO), which is a measure of how much

oxygen is dissolved in the water. It helps a lot to describe the quality of water. Basically, the

oxygen dissolved in lakes and river. The lower the dissolved oxygen below its normal

standard, the higher the creatures begin to die. Usually, moving water such as stream contains

a lot of dissolved oxygen compare to stagnant water. As stated in Water Quality Control, “ A

moving waterway is replenished with dissolved oxygen surface to replace oxygen used by

organism in water to biologically treat organic pollutant “ . The creatures or aquatic life in the

stagnant water have a hard time because it has a lot of rotting, organic material especially

during hot day. This is because water that has higher temperature is tends to have lower

dissolved oxygen. Other measurement to test the quality of water is through the physical test

such as pH, colour, odour, and temperature. For example, the pH of water determines the

solubility and biological availability of the sample of water. pH ranges is from 0 to 14, which

7 is neutral, pHs less than 7 are acidic and pHs that greater than 7 are alkaline. In conclusion,

the basic water quality experiment will give the chance to student to observe by themselves

how to recognize and identify the quality of water. The basic water quality help to determine

the quality of water either it safe or not to the ecosystem.

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OBJECTIVE

The objective of this experiment was to determine the amount of carbon dioxide in the

sample water. Besides, from the experiment, the amount of dissolved oxygen in sample

water using 300 ml bottle were identified too. Next, the temperature and pH of the sample

were measured. Through the experiment, the relationship between the living things around

the source of sample water were taken and the amount of dissolved oxygen in the sample

water were studied.

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THEORY

Table 1 : Calculation of the amount of carbon dioxide in water

Range (mg/L as CO2) Sample volume (mL) Titration cartridge

(NaOH)

Multiplier

10-50 200 0.3636 0.1

20-100 100 0.3636 0.2

100-400 200 3.636 1

200-1000 100 3.636 2

Concentration of CO2 in sample water (mg/L CO2) = digits X multiplier.

Table 2 : Calculation of the amount of dissolved oxygen in 300 Ml BOD bottle :

Range (mg/L DO) Volume (mL) Titration cartridge

(Na2S2O3)

Digit Multiplier

1-5 200 0.2 0.02

2-10 100 0.2 0.02

>10 200 2 0.1

Concentration of the O2 in sample water using 300 ml BOD bottle (mg/L O2)

= Digits required X Digits Multiplier

Digits required : the number of digits displayed on the counter when titrated.

DESCRIPTION OF APPARATUS

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DESCRIPTION OF APPARATUS

In Carbon Dioxide test, 0.3636 N Sodium Hydroxide Titration Cartridge is used.

Sodium Hydroxide Titration Cartridge is an apparatus that filled with Sodium Hydroxide

which is used as a titrant. The cartridge was attached to the digital titrator along with a

delivery tube. Then Sodium Hydroxide was added into the solution until the solution

turned to light pink color. The concentration of Carbon Dioxide of the water sample can

be calculated by inserting the number of digits appeared on the counter at the titrator body

into the formula. Phenolphthalein Indicator Powder Pillow is used in the test to determine

the presence of Carbon Dioxide. The solution did not make a change after the powder

pillow was added, which showed the absence of Carbon Dioxide. If Carbon Dioxide was

present, the solution changes to pink color.

A titration cartridge, a digital titrator and a delivery tube are also used in Dissolved

Oxygen test, except in this test, 0.2 N Sodium Thiosulfate Titration Cartridge is used.

Sodium Thisulfate is used as a titrant. Manganous Sulfate Powder Pillow and Alkaline

Iodide-Azide Reagent Powder Pillow are added in the solution at the same time to test the

presence of Oxygen. The orange-brown precipitate is formed, shows the presence of

Oxygen. If not, the precipitate would be in white color. Sulfamic Acid Powder Pillow is

used to test the presence of Oxygen. It is used a few steps after both of the reagents above

are added. The precipitate changed to yellow color as Oxygen was present. Another

reagent used for the experiment is Starch Indicator. When the reagent was added, the

solution turned to dark blue color. It shows the presence of oxygen in the solution.

To test the pH and temperature of the water sample, Sension 2 Portable pH/ISE Meter

is used to determine the pH and temperature. Potassium Chloride Electrolyte Cartridge is

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installed in Platinum Series Combination pH Electrode with Temperature. Then the

electrode is connected to the pH meter. Only then they become a complete apparatus and

can be used for the experiment.

EXPERIMENTAL PROCEDURES

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EXPERIMENT 1: CARBON DIOXIDE TEST USING DIGITAL TITRATOR

METHOD USING SODIUM HYDROXIDE

PROCEDURES

1. A sample volume of 200 ml and 0.3636 N Sodium Hydroxide titration

cartridge was selected from Table 1.

2. A clean delivery tube was inserted into the titration cartridge and the cartridge

was attached to the titrator.

3. The delivery knob was turned slightly just to eject air and a few drops of

titrant. The counter was reset to zero and the tip was wiped.

4. To avoid agitation, a water sample was collected directly into the Erlenmeyer

flask y filling to the volume chosen in step 1.

5. The contents of one Phenolphthalein Indicator Powder Pillow were added. The

flask was swirled for mixing. Carbon Dioxide was present as the solution

remained the same.

6. The delivery tube was placed into the solution and the knob was turned on the

titrator to add titrant to the solution. The flask was swirled while adding the

titrant until the color changed to light pink that lasted for 30 seconds. The

number of digits displayed on the counter was recorded.

7. The concentration of carbon dioxide in sample water was calculated using the

multiplier in Table 1.

8. Step 1 to 7 was repeated for the second water sample.

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EXPERIMENT 2: DISSOLVED OXYGEN TEST USING AZIDE

MODIFICATION OF WRINKLER METHOD

PROCEDURES

1. A water sample in a 300 ml BOD bottle was collected. The sample was

allowed to overflow the bottle to make sure that no air was trapped in the

bottle.

2. The contents of one Manganous Sulfate Powder Pillow and one Alkaline

Iodide-Azide Reagent Powder Pillow were added.

3. The stopper was inserted immediately without trapping air in the bottle

before it was inverted several times. An orange-brown flocculent precipitate

was formed which indicated the presence of oxygen. The flocs were let to

settle.

4. The bottle was inverted several times again and the flocs were let to settle

until the top half of the bottle was cleared to make sure that the reaction in

the bottle was completed.

5. Then the contents of one Sulfamic Acid Powder Pillow were added. The

stopper was replaced without trapping air in the bottle. Then the bottle was

inverted several times. The flocs were dissolved and left a yellow color

which shows the presence of oxygen.

6. A sample volume of 200 ml and 0.2 N Sodium Thiosulfate titration cartridge

that corresponded to the expected dissolved oxygen (DO) concentration

were selected from Table 2.

7. A digital titrator was set up as in Experiment 1.

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8. A graduated cylinder was used to measure the sample volume chosen from

Table 2. The sample was transferred into 250 ml Erlenmeyer flask.

9. The solution was titrated as in Experiment 1 by using digital titrator with

Sodium Thiosulfate as a titrant to a pale yellow color.

10. Two 1 ml droppers of Starch Indicator Solution were added and the flask

was swirled again. A dark blue color was developed.

11. Then the titration was continued to a colorless end point. The number of

digits required was recorded.

12. The amount of dissolved oxygen content in water sample was calculated.

13. Step 1 to 12 was repeated for the second water sample.

EXPERIMENT 3: pH AND TEMPERATURE OF SAMPLE WATER

PROCEDURES

1. The Potassium Chloride Elecrolyte Gel Cartridge was installed in the Platinum

Series pH Electrode.

2. The electrode was primed by pushing the dispenser button until gel came out

of the reference junction. The tip and the outlet were rinsed using deionized

water.

3. The electrode was connected to the sension2 pH/ISE meter.

4. The meter was turned on by pressing I/O. pH mV was pressed until the display

showed pH.

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5. SETUP was pressed. The up arrow was pressed three times. ENTER was

toggled to the number of desired decimal places, then EXIT was pressed to

leave setup.

6. CAL was pressed and the display showed ‘Standard 1?’.

7. Electrode was rinsed in deionized water and was blotted dry.

8. The electrode was placed in the water sample that was used in Experiment 1

and Experiment 2. ENTER was pressed. The display showed ‘Stabilizing…’.

9. The display showed ‘Standard 2?’ when a stable pH was determined. The

electrode was removed from the cup. Then it was rinsed with deionized water

and was blotted dry. The pH and temperature readings were recorded.

10. The electrode was placed in the second water sample that was used for

Experiment 1 and Experiment 2. ENTER was pressed.

11. After the last calibration point has stabilized and the display read ‘Standard

3?’, EXIT was pressed. The pH and temperature readings were recorded.

12. The display showed ‘Store?’. ENTER was pressed to store the calibration.

13. The electrode was removed from the water sample. It was rinsed with

deionized water followed by a small amount of sample and was blotted dry.

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RESULTS

(i) Source of water = Drain water

Test Temperature

(ºC)

pH Digit Multiplier Concentration

(mg/L)

Carbon

Dioxide,CO2 28.2 7.04 357 0.1 35.7

Dissolved

Oxygen, DO

(300ml)

28.2 7.06 275 0.02 5.5

(ii) Source of water = CO2 rich water

Test Temperature

(ºC)

pH Digit Multiplier Concentration

(mg/L)

Carbon

Dioxide,CO2 26.0 7.27 40 2 80

Dissolved

Oxygen, DO

(300ml)

26.1 7.13 415 0.02 8.3

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Carbon dioxide, CO2 Dissolve oxygen, DO using 300 mL BOD bottle

0

5

10

15

20

25

30

35

40

Drain water

Temperature (˚C)pHConcentration (mg/L)

Carbon dioxide,CO2 Dissolved oxygen, DO using 300ml BOD bottle

0

10

20

30

40

50

60

70

80

90

CO2 rich water

Temperature (˚C)pHConcentration (mg/L)

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DISCUSSION

Carbon dioxide and dissolved oxygen test of sample water is important to ecosystem.

This is because when there is more dissolved oxygen in the water sample, it means that there

are aquatic lives living in the water. But if there is more carbon dioxide in the water sample,

it means that the water sample is polluted and it can bring harm to the aquatic life.

Oxygen present in the water via the process of photosynthesis. When the sunlight

expose to the aquatic plant, there will be exchange of gas from carbon dioxide to oxygen.

Carbon dioxide present in the water by the process of bacteria decomposition. When there is

more aquatic plant in the water then there will be more bacteria to decompose the aquatic

plant and increase the carbon dioxide in the water.

The value of carbon dioxide concentration in both water samples are high range. This

is because the water samples are collected from the drain and CO2 rich water. Drain water is

unclean and polluted water while CO2 rich water is high in carbon dioxide. That is why the

value of carbon dioxide concentration in both water samples is high range.

The value of dissolved oxygen concentration in water samples are low range. This is

because the water samples are collected from the drain and CO2 rich water. Drain water is

low in oxygen because of the decomposition of bacteria in the water while CO2 rich water is

low in oxygen. That is why the value of dissolved oxygen concentration in water samples is

low range.

The average temperature in the water sample is around the room temperature which is

27.1 ºC. This is because the water sample that was collected was not heated or cooled during

the experiment. The average pH value in the water sample is about 7.13. The water sample is

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a bit alkaline because of the soap and other contamination from the drain water and the

disinfection process from the water treatment plant.

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SAMPLE CALCULATION

For experiment using drain water:

Concentration of carbon dioxide in water sample (mg/L CO2) = digits x multiplier

= 357 x 0.1

= 35.7

Concentration of the O2 in water sample using 300 ml = digits x multiplier

BOD bottle (mg/L O2) = 275 x 0.02

= 5.5

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CONCLUSION

1. The amount of carbon dioxide in both water samples was higher than the amount of oxygen.

2. The temperature and the pH values in both water samples were around the average

value which were 27 ºC and 7.13.

3. The higher the number of digits, the higher the concentration of carbon dioxide and

oxygen in the water sample.

4. The concentration of carbon dioxide and oxygen in the water sample depends on the

source of water itself.

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RECOMMENDATION

1. Conduct the experiment more than one time for each water sample to obtain more

accurate consistent result.

2. Use more than one sources of water because different sources of water has different

amount of carbon dioxide and oxygen, temperature and pH values.

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REFERENCES

1. Roberts Alley, E., Water Quality Control, Second Edition., New York, NY :

McGraw-Hill, pp. 1.1 to 1.2 (2002)

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