Exp.7 Alkalinity Test

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FACULTY OF ENGINEERING TECHNOLOGY

DEPARTMENT OF CIVIL ENGINEERING TECHNOLOGY

ENVIRONMENTAL ENGINEERING TECHNOLOGY LABORATORY

LABORATORY INSTRUCTION SHEETS

COURSE CODE BNP 20503

EXPERIMENT CODE EXPERIMENT 7

EXPERIMENT TITLE DETERMINATION OF ALKALINITY

DATE

GROUP NO.

LECTURER/INSTRUCTOR/TUTOR1)

2)

DATE OF REPORT SUBMISSION

DISTRIBUTION OF MARKS FOR LABORATORY REPORT

ATTENDANCE/PARTICIPATION/DISIPLINE: /5%

INTRODUCTION: /5%

PROCEDURE: /5%

RESULTS & CALCULATIONS /15%

ANALYSIS /15%

DISCUSSIONS: /20%

ADDITIONAL QUESTIONS /15%

CONCLUSION /10%

SUGGESTIONS & RECOMENDATIONS /5%

REFERENCES: /5%

TOTAL: /100%

EXAMINER COMMENTS: RECEIVED DATE AND STAMP:

STUDENT CODE OF ETHICS

FACULTY : ENGINEERING TECHNOLOGY

EDITION:

LABORATORY: CIVIL ENGINEERING TECHNOLOGY

REVISION NO: 2

EXPERIMENT: DETERMINATION OF ALKALINITY

EFFECTIVE DATE: FEB 2015

AMENDMENT DATE:

2

STUDENT CODE OF ETHICS


EDITION:


REVISION NO: 2



AMENDMENT DATE:

1.0 OBJECTIVES

a) To determine the alkalinity of a water sample using analytical method

(indicator method) – double endpoint; phenolphthalein endpoint (pH 8.3)

and methyl orange endpoint (pH 4.5) titration.

2.0 LEARNING OUTCOMES

At the end of this course students are able to:

a) the student be able to describe the importance of alkalinity in the

environmental studies.

b) the students be able to measure the alkalinity of samples

3.0 INTRODUCTION

3.1 Alkalinity is a parameter that is measured on almost all environmental

samples -drinking water, natural waters, polluted waters, sewage, and

industrial wastes. Alkalinity refers to the buffering capacity of water

samples and to their ability to neutralize acidic pollution from rainfall or

wastewater. For municipal sewage or industrial wastes, the amount of

alkalinity is important in determining the type of treatment which should

be employed.

3.2 Alkalinity is primarily caused by the presence of carbonate (C02-3) and

bicarbonate (HCO-3) ions, although hydroxide (OH-) ions may also

contribute, especially when there is industrial pollution. It is measured

volumetrically by titration with 0.05 N sulphuric acid and is reported in

terms of CaCO3 equivalent. For samples whose initial pH is above 8.3, the

titration is conducted in two steps.

3.3 In the first step, the titration is conducted until the pH is lowered to 8.2,

the point at which phenolphthalein indicator turns from pink to colourless.

This value corresponds to the points for conversion of carbonate to

bicarbonate ion.

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3.4 The second phase of titration is conducted until the pH is lowered to 4.5,

corresponds to methyl orange end point, which corresponds to the

equivalence points for the conversion of bicarbonate ion to carbonic acid.

3.5 Living organisms, such as aquatic life, function best in a pH range of 5.0 to

9.0 and levels of 20 to 200 mg/L are typical alkalinity values for fresh

water. When the pH is above 8.3, carbonate (CO2-3) is the primary

contributor to alkalinity; when the pH is below 8.3, bicarbonate (HCO -3)

becomes the dominating factor. The values of alkalinity are reported in

units of "mg CaCO3/L" because of its relationship to hardness, which is

reported using the same unit.

4.0 INSTRUMENTS /APPARATUS / CHEMICAL / REAGENTS

This experiment consists of three parts:

Part A: Preparation of 0.05 M H2SO4 solutions

Part B: Preparation of phenolphthalein indicator solution

Part C: Preparation of methyl orange indicator solution

Part D: Alkalinity determination

Part A, B and C will be prepared by laboratory technician prior to the experiment

session.

Part A:

a. Chemicals

(i) Concentrated sulphuric acid

(ii) Distilled water

b. Equipments

(i) 1-litre volumetric flask

(ii) Digital pipette, and

(iii) 1000-mL (1 L) Duran bottle

Part B:

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This part must be conducted in area away from sources of ignition.

a. Chemicals

(i) 50 ml of ethanol

(ii) 0.5 g of phenolphthalein(iii) Distilled water

b. Equipments(i) Digital pipette(ii) Weighing boat(iii) 100-ml volumetric flask(iv) small funnel(v) 100-ml dropper bottle.

Part C:a. Chemicals

(i) 0.1 g of methyl orange (ii) Distilled water

b. Equipment

(i) 100 ml beaker

(ii) 100 ml volumetric flask

(iii) weighing boat

(iv) small funnel

Part D:

a. Chemicals

(i) 0.05 M H2SO4 solution (prepared from Part A)

(ii) Phenolphthalein indicator solution (prepared from Part B)

(iii) Methyl orange indicator solution (prepared from Part C)

(iv) Water sample

b. Equipments

(i) Burette

(ii) Clamp stand

(iii) Volumetric flask

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6 RESULTS CALCULATIONS

Part A: Preparation of 0.05 M H2SO4 solution

6.1. Half-fill a 1-litre volumetric flask with distilled water.

6.2. From a bench acid container of concentrated sulphuric acid, and using a

digital pipette, pipette 2.8 ml of acid into the flask. Swirl to mix. Rinse

the tip under running cold water immediately after use.

6.3. Make the solution up to 1-litre with distilled water.

6.4. Cap tightly and shake well to mix.

6.5. Pour into a 1-litre Duran bottle and label it.

Part B: Preparation of phenolphthalein indicator solution

6.1. Using a digital pipette, pipette 50 ml of ethanol into a 100ml volumetric

flask.

6.2. Weigh out 0.5 g of phenolphthalein into a weighing boat.

6.3. Place a small funnel into the neck of the volumetric flask and tip the

powder into it.

6.4. Wash the powder into the flask with distilled water, mix gently to

dissolve.

6.5. Make up to the 100 ml mark with distilled water. Cap tightly, shake to

mix.

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6.6. Using a small funnel, transfer to a 100ml, appropriately marked,

dropper bottle.

Part C: Preparation of methyl orange indicator solution

6.1. Weigh out 0.1 g of methyl orange into a small beaker (100 ml).

6.2. Add about 50ml of distilled water, stir to dissolve.

6.3. Wash the contents of the beaker into a 100 ml volumetric flask and

make up to 100 ml with distilled water. Stopper and shake to mix.

Using a small funnel, transfer to an appropriately marked dropper

bottle.

Part D: Alkalinity determination

6.1. Clean burette with distilled water, allow to drain.

6.2. Ensure burette is secure in the clamp stand.

6.3. Pour about 40 ml of the 0.05 M acid into a small beaker very slowly.

6.4. Insert the funnel into the top of the burette and pour in the contents of

the beaker very slowly.

6.5. Allow the acid to flow through the burette, top up as necessary.

6.6. Place 100ml (or record another known volume as “V”) of sample in a

250 ml conical flask.

6.7. Add 2-3 drops of phenolphthalein indicator.

6.8. If no pink colour is produced, record the titre as A= 0ml.

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6.9. If the sample turns pink, titrate with the standard acid solution until the

pink colour just disappears. Note down the volume of acid used as A

(ml).

6.10. To the same sample, add a few drops of methyl orange indicator.

6.11. If the sample turns red, record the titre as B=0ml.

6.12. If the sample turns yellow, titrate with the standard acid until the colour

just changes to red. Note down the volume of acid used as B (ml).

(Repeat the same procedures using different samples)

6 ANALYSIS

Please show the calculation for each of the plating method and fill in the

above table. Analyze the results by using appropriate method. Explain your

findings.

If the amount of acid recorded as “A” was zero, then phenolphthalein

alkalinity is 0 mg CaCO3/L.

If the amount acid recorded as “A” was > zero, then calculate

phenolphthalein alkalinity as follows:

Phenolphthalein alkalininty (mg/L as CaCO3)= A x C x 1000 x100

V

If the amount of acid recorded as “B” was zero, then total alkalinity is 0

mg CaCO3/L.

If the amount of acid recorded as “B” was > zero, then calculate total

alkalinity as follows:

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Total alkalininty (mg/L as CaCO3) = B x C x 1000 x100

V

Where:

A = volume of standard acid titrated to reach phenolphthalein endpoint

(pH 8.3) [ml]

B = volume of standard acid solution required to reach methyl orange

endpoint (pH 4.5) [ml]

C = concentration of acid [0.05 M]

V = volume of sample used [usually 100 ml].

Table 1: Alkalinity data (Sample 1: tap water )

Table 2: Alkalinity data (Sample 2: wastewater effluent )

Table 3: Alkalinity data (Sample 3: lake wastewater )

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Sample IDA

(ml)B

(ml)Phenolphthalein Alkalinity (mg

CaCO3/L)

Total Alkalinity (mg

CaCO3/L)Sample 1

Sample 1

Sample 1

Average

Conc. of acid, C [M] 0.05

vol. of sample used, V (ml)

100

Sample IDA

(ml)B

(ml)

Phenolphthalein Alkalinity (mg

CaCO3/L)


CaCO3/L)

Sample 1

Sample 1

Sample 1

Average



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7 DISCUSSIONS

State the systematic bias error that could occur during this experiment and

readings for different samples.

8 ADVANCED QUESTIONS

8.1 What is alkalinity?

8.2 What is relationship between alkalinity and hardness?

8.3 Define equivalent weight and determine equivalent of CaCO3.

8.4 Discuss the importance of alkalinity to the environment.

9 CONCLUSION

Conclusion is merely a summary, presented in a logical order, of the

important findings already reported in the discussion section. It also relates

to the objectives stated earlier.

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Sample IDA

(ml)B

(ml)

Phenolphthalein Alkalinity (mg

CaCO3/L)


CaCO3/L)

Sample 1

Sample 1

Sample 1

Average



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AMENDMENT DATE:

Prepared by/Disediakan oleh :

Signature/Tandatangan : Name/Nama : DR. NOR HASLINA HASHIM

Date/Tarikh : FEBRUARY 2015

Approved by/Disahkan oleh :

Signature/Tandatangan : Name/Nama : DR. SURAYA HANI ADNAN

Date/ Date/Tarikh : FEBRUARY 2015

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Documents

Exp.7 Alkalinity Test