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ENGINEERING CHEMISTRY LAB MANUAL

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Engineering Chemistry Lab Manual

Page | 2 B V Raju Institute of Technology (UGC Autonomous)



List of Experiments: Titrimetry: 1. Estimation of ferrous iron by dichrometry. 2. Estimation of hardness of water by EDTA method. Mineral analysis: 3. Determination of percentage of copper in brass. 4. Estimation of manganese dioxide in pyrolusite. Instrumental Methods: Colorimetry: 5. Determination of ferrous iron in cement by colorimetric method 6. Estimation of copper by colorimetric method. Conductometry: 7. Conduct metric titration of strong acid vs strong base. 8. Conduct metric titration of mixture of acids vs strong base. Potentiometry: 9. Titration of strong acdvs strong base by potentiometry. 10. Titration of weak acid vs strong base by potentiometry. Physical properties 11. Determination of viscosity of sample oil by redwood / Oswald’sViscometer 12. Determination of Surface tension of lubricants. Preparations 13. Preparation of Aspirin 14. Preparation of Thiokol rubber Adsorption: 15. Adsorption of acetic acid on charcoal. TEXT BOOKS: 1. Practical Engineering Chemistry by K. Mukkanti, etal, B.S. Publications, Hyderabad. 2. Inorganic quantitative analysis, Vogel. REFERENCE BOOKS: 1. Text Book of engineering chemistry by R. N. Goyal and HarrmendraGoel, Ane Books Private Ltd., 2. A text book on experiments and calculation Engg. S.S. Dara. 3. Instrumental methods of chemical analysis, Chatwal, Anand, Himalaya Publications



GENERAL PRECAUTIONS TO BE TAKEN IN THE

LABARATORY

1. Never work in the laboratory unless a demonstrator or teaching assistant is present.

2. Do not throw waste such as match stems filter papers etc. into the sink. They must be

thrown into the waste jars.

3. Keep the water and gas taps closed expect when these utilities are needed.

4. Never taste any chemical unless instructed to do so and don’t allow chemicals to come

in contact with your skin.

5. While working with gases, conduct the experiment in a fume hood.

6. Keep all the doors and windows open while working in the laboratory.

7. You should know about the hazards and properties of every chemical which you are

going to use for the experiment. Many chemicals encountered in analysis are poisonous

and must be carefully handled.

8. Sulphuric acid must be diluted only when it is cold .This should be done by adding it

slowly to cold water with stirring ,and not vice versa.

9. Reagent bottles must never be allowed to accumulate on the work bench. They should

be placed back in the shelves as and when used.

10. Containers in which reaction to be performed a little later should be labeled. Working

space should be cleaned immediately.



INSTRUCTIONS FOR RECORD WRITING

1. Write on the right hand page the following order:

a) Serial number and date of performance (in the margin)

b) Name and number of the experiment as given in the list.

c) Aim of the experiment.

d) Description of the apparatus.

e) Procedure including sources of error and precautions taken to eliminate or to

minimize them.

f) Inference or Result.

g) Explanation, if necessary of any divergence in the expected result.

2. Left hand page should contain the following in their proper places.

a) Neat diagram of the main apparatus.

b) Observation in tabular form.

c) Calculation in tabular form.

d) Graph sheets and other papers to be attached.

3. Students should submit a record of the previous experiments when they come for

practical work.

4. An experiment is deemed to be complete when it is satisfactorily performed and

recorded.

KEEP THE RECORD BOOK NEAT IT FETCHES MARKS.



VOLUMETRIC ANALYSIS

BASIC CONCEPTS OF VOLUMETRIC ANALYSIS

Chemical analysis of the compounds is carried out in two ways

1. Qualitative analysis.

2. Quantitave analysis.

Qualitative analysis shows what element a given contains.

Quantities analysis determines the quantity of a particular component present in substance.

It is carried out in two ways

1. Gravimetric analysis.

2. Volumetric analysis.

Gravimetric analysis involves the estimation of the amount of a given compound from the

results of weighing.

Volumetric analysis is based on the measuring the volume of the solution of a substance.

Terms involved in volumetric analysis

1. Titration: The process of finding out the volume of one of the solution required to react

completely with a definite volume of one the other solution of known concentration is called

titration.

2. Titrant: The solution of known strength is called titrant.

3. Titrate: The solution whose concentration to be estimated.

4. Indicator: The reagent which indicates the endpoint or equivalent point of the titration.

The strength of concentration of a solution is expressed in the following ways.

NORMALITY:

Number of gram equivalents of the substance dissolved per liter of the solution is called

Normality.

It is denoted by N

Normality = Wsolute/Esolute × 1/Vsovent (in lit)

Where E is Gram equivalent weight

MOLARITY:

Number of grams moles of a solute dissolved per liter of solution is called Molarity.

It is denoted by M

Molarity = Wsolute/Msolute × 1/Vsovent (in lit)

Where M is Gram molecular weight

MOLALITY:

It is the number of mole of the substance dissolved in 1kg of the solvent it is denoted by (m).

Molality = Wsolute/Msolute × 1/Wsovent (in kg)



EXPERIMENT-I

ESTIMATION OF FERROUS IRON BY DICHROMETRY

AIM: To estimate the amount of ferrous iron present of the whole solution with the help of

standard solution of potassium dichromate.

APPARATUS: Beaker, burette, pipette, conical flask, volumetric flask.

CHEMICALS: K2Cr2O7, diphenylamine, Conc. H2SO4, Distilled water.

THEROY AND PRINCIPLE:

Ferrous iron is oxidized to ferric iron by potassium dichromate in acid solution. The completion

of the oxidation of reaction is marked by the appearance of blue violet color of the

diphenylamine which is used as an internal indicator.

K2Cr2O7 +4H2SO4 → K2SO4 +Cr2 (SO4)3 +4H2O+3(O)

3[2FeSO4 +H2SO4+ (O) → Fe (SO4)3 +H2O]

K2Cr2O7 +6FeSO4 + 7H2SO4→K2SO4 + 3Fe2 (SO4)3 +Cr (SO4)3 + 7H2O

The equivalent weight of iron is its atomic weight i.e.55.86 since one equivalent of potassium

dichromate oxidizes one equivalent of iron.

PROCEDURE:

1) Preparation of standard potassium dichromate: weigh out accurately about 0.49gms of

potassium dichromate into a standard flask into a100 ml standard flask and dissolve the

solid in a small quantity of distilled water .make up the resulting solution with distilled

water up to the mark and shake the flask well for uniform concentration.

2) Preparation of acid mixture: Mix up 100 ml of phosphoric with 300ml of concentrated

H2S04 in a reagent bottle and stopper it.

3) Preparation of diphenylamine: Dissolve 1gm of diphenylamine in 100ml of concentrated

H2S04.

Standardization of ferrous iron:

Rinse the burette with K2Cr2O7 solution and take K2Cr2O7 solution up to the zero of the

burette. Pipette out 20ml of ferrous solution into a 250ml conical flask, add 5ml of acid

mixture and 2drops of diphenylamine indicator. Titrate the resulting solution with

potassium dichromate taken in the burette till blue violet color is obtained as end point.

Repeat the titration to get concurrent values.



CALCULATIONS AND OBSERVATIONS:

S.No Fe+2 Solution(in ml) Burette reading

Initial final

Volume of k2cr2o7

Consumed (in ml)

Normality of K2Cr207 (N) = Wt .of K2Cr207 *10 / 49

Normality of ferrous iron (N2): N1V1 =N2V2

V1 = Volume of K2Cr207 (Titrevalue ….ml)

N2= Normality of K2Cr207

V2= Volume of ferrous iron

N2 =NIVI / V2 = Titer value* N1 / 20

RESULT: Amount of ferrous iron present in the given solution = ……………..gms/100ml.



EXPERIMENT-2

Estimation of Hardness of water by EDTA method

AIM: To determine the total hardness, permanent hardness and temporary hardness of water

APPARATUS: Pipette,Burette,standard flask, conical flask,beaker,funnel.

CHEMICALS:Standard sample water, Buffer solution,EBT (Erichrome black –T)

indicator,distilled water EDTA(Ethylene diamine tetra acetic acetate)

PRINCIPLE: Calcium and magnesium ions which are present in standard water forms a weak

complex with EBT with wine red colour

Ca2+ / Mg2+ + EBT [Ca / Mg –EBT]

Unstable wine red complex

Then the solution is titrated against EDTA results in the formation of stable complex

changing colour from winered to blue

[Ca / Mg –EBT] + EDTA [Ca / Mg –EDTA] + EBT

(Wine red/unstable) (Stable) (Blue)



PROCEDURE:

STEP-1

STANDARDDISATION OF EDTA:

Pipette out 25 ml of standard hard water into a conical flask .To this add 5ml of buffer solution

followed by addition of 3 to 4 drops of EBT indicator. Then titrate against EDTA which is taken

in the burette. Continue the titration till wine red colour changes to blue colour. Repeat this

process until two concurrent values are obtained.

STEP-2

ESTIMATION OF TOTAL HARDNESS OF SAMPLE WATER

Take 50 ml of sample water into a conical flask.To this add 5ml of buffer solution

followed by addition of 3 to 4 drops EBT indicator.Then titrate against with EDTA which is

taken in burette.Continue the titration till winered colour to blue colour. Repeat this titration

until two concurrent values are obtained.

STEP-3

ESTIMATION OF PERMANENT HARDNESS OF SAMPLE WATER

Take 100ml of sample water in the beaker. Boil the water until its volume reduces to 50ml.Filter it into a standard volumetric flask and make the solution upto 100ml by adding distilled water. To this add 3 to 4 drops of EDTA indicator.Then titrate it against EDTA which is taken in the burette.continue the titration till wine red colour changes to blue colour. Repeat this process until two concurrent values are obtained. RESULT:



EXPERIMENT-3

ESTIMATION OF PERCENTAGE OF COPPER IN BRASS

AIM: To determine the CU present in given brass sample by idometrically.

APPARATUS: Burette, Pipette, Conical Flask, Iodination flask, Standard Volumetric flask.

CHEMICALS: Standard Sodium thiosulphate (Na2S2O3), Hypo, Potassium iodide solution (KI),

CH3COOH, Starch, Dil HNO3, 0.1 N Hypo

PRINCIPLE: Cupric salt in neutral media when treated with KI forms a white PPT of Cuprous

iodide and decompose to liberate iodine, By estimating the liberated iodine CU can be

estimated.

𝐶𝑢 + 2𝐻𝑁𝑂3 → 𝐶𝑢(𝑁𝑂3)2 + 𝐻2 ↑

2𝐶𝑢(𝑁𝑂3)2 + 4𝐾𝐼 → 2𝐶𝑢𝐼2 + 4𝐾𝑁𝑂3

2𝐶𝑢𝐼2 → 𝐶𝑢2𝐼2 + 𝐼2

2𝑁𝑎2𝑆2𝑂3 + 𝐼2 → 𝑁𝑎2𝑆4𝑂6 + 2𝑁𝑎𝐼

2𝐶𝑢𝐼2 + 𝐼2 → 2𝑁𝑎2𝑆2𝑂3

PROCEDURE:

STEP I: DISSOLUTION OF BRASS:

Take the accurately weighted sample into 250ml beaker to that add 10ml of dil HNO3. Keep nit

on hot pan for heating purpose till the sample completely dissolve. Then transfer this solution

into clean 100ml standard volumetric flask by using funnel. Make up the solution up to 100ml

by adding distilled water.

STEP II: ESTIMATION OF CU IN BRASS:

Pipette out 200ml of solution from the standard volumetric flask. Add NH4OH till blue

color appears. Then add CH3COOH till its position in the solution becomes clear. To this add

20ml of KI and keep it in dark for 5mins. Then the color changes to thick brown color. After 5

min remove the Iodination flask from dark place and rinse the walls of the flask with

approximately 50ml of distilled water. Then titrate this against Hypo which is taken in burette.

The titration continues till the color changes to pale brown. Then add 3 drops of starch

indicator. Then color changes to black and titrate against Hypo until solution becomes clear. I.e.

Milky white.

RESULT:



EXPERIMENT-4

ESTIMATION OF MNO2 IN PYROLUSITE

AIM: To estimate the amount of Manganese dioxide present in given pyrolusite sample by using

the standard potassium permanganate.

APPARATUS: Burette, Conical Flask, Funnel

CHEMICALS REQUIRED: Pyrolusite, 0.5 N Sodium oxalate, 0.3 N KMNO4, Dil H2SO4

PRINCIPLE: MNO2 present in pyrolusite is reduced by a known excess of oxalic acid in acidic

medium. Unreacted oxalic acid is treated against standard solution of KMNO4 till colour changes

to pink colour

Na2C2O4 + H2SO4 H2C2O4

Mno2 + H2C2O4+ H2SO4 MnSO4 + 2H2O + 2CO2

2KMnO4 + 3H2SO4 2MnSO4 + K2SO4 + 3H2O + 5 (O)

5 H2C2O4 + 5(O) 5H2O + 10 CO2

2KMnO4 + 3H2SO4 + 5H2C2O4 → 2MnSO4 + K2SO4 + 8H2O + 10 CO2

PROCEDURE: Weigh out the given sample and transfer the sample into conical flask. 40ml of

sodium oxalate followed by the addition of 50ml dil H2SO4 by keeping the funnel in the mouth

of conical flask. Then keep the conical flask along with funnel on hot pan for heating purpose

and continue till the black colored MNO2 particles disappeared in the solution and ring the

conical flask by adding 10 ml distilled water. Then titrate that solution against standard KMNO4

which is taken in burette and continue the titration till the change of colour from colourless to

pink. Then calculate the amount of oxalic acid consumed. From this it is possible to determine

MNO4 from pyrolusite.

RESULT:



EXPERIMENT-5

ESTIMATION OF IRON IN CEMENT BY COLORIMETICALLY



EXPERIMENT-6

ESTIMATION OF COPPER BY COLORIMETRIC METHOD

AIM: Estimation of Copper by Colorimetry

APPARATUS: - Colorimeter, Test tubes, Burettes.

PRINCIPLE: - Colorimeter measures the optical density of an absorbing substance where optical

density (O.D) is defined as O.D = log 1oI

I

Where oI = Intensity of incident light

I = Intensity of transmitted light

As per beers law, optical density of an absorbing substance is related to the concentration by the

equation. . . .O D E C l

. ( . ). 2O D E l C

Where ‘C’ is the concentration of the substance, l is the path length, which represents the width

of the cell used and is constant for a given cell used, E is the molar absorption coefficient and is a

constant for given substance. Equation 2 may be written as O.D. C 3

Equation 3 represents the quantitative form of Beer’s law. if the optical density of a substance is

determined at varying concentration. A plot of O.D.vs C gives a straight line.

PROCEDURE:- take the sample solution of CuSo4 and prepare the following 10 sample solutions

in test tubes as 1 to 10

1. 1 ml 0.1 m CuSo4 + 9 ml Distilled water








9. 9ml 0.1 m CuSo4 + 1 ml Distilled water




The ten sample solutions prepared above have a varying concern from 0.01m to 0.1m, choose the

filter in the colorimeter with maximum absorbance. Tabulate the result of filter and O.D with a

given CuSo4 sample solutions.

After selecting filter, determine the O.D. of the above mentioned ten sample solutions and tabulate

the results.

Observation:

Table-1

Filter No -Range (nm) Peak (nm) Optical Density(OD)

1

2

3

4

5

6

7

8



Table-II Selected Filter--------------------

Sl.No Volume of

4CuSo (ml)

Volume of

2H O (ml)

Concentration of

4CuSo Optical Density

1

2

3

4

5

6

7

8

9

10

10

9

8

7

6

5

4

3

2

1

0

1

2

3

4

5

6

7

8

9

GRAPH: - Plot a graph of O.D Vs [CuSo4]. A straight line passing through origin is obtained

the slope of which gives El, E is the molar

absorption coefficient.

Slope 2 1

2 1

y y

x x

1

slopeslope El E

l

E mole cm

RESULT: - Amount of copper present in given CuSo4 solution is _________grams



EXPERIMENT-7

CONDUCTOMETRIC TITRATION OF STRONG ACID Vs STRONG BASE



EXPERIMENT-8

CONDUCTOMETRIC TITRATION OF MIXTURE OF ACIDS Vs STRONG BASE

AIM: - To determine the composition of mixture of acids by Conduct metrically

APPARATUS: - Conductivity meter, conductivity cells, Beakers, Pipette, Burette, conical flask

CHEMICALS: - acetic acid Solution (0.01N), NaOH Solution (0.1), HCl,

PRINCIPLE: - When mixture containing CH3COOH and HCl is titrated against an alkali strong acid

will be neutralized first, the neutralization of weak acid commences only after the completion of

strong acid. Then conductance titration curve will be marked by two breaks, the first one

corresponds to neutralization of HCl and second one to that of CH3COOH.

Let v1 & v2 ml be the volume of alkali corresponding to 1st and 2nd breaks, respectively.

V1ml of NaOH = HCl

(v1-v2) ml of NaOH = CH3COOH

PROCEDURE: -

Take 0.1 N NaOH solution and 0.01 N acetic acid Solution and 0.01 N HCl in a

beaker. Fill the micro burette with 0.1 N NaOH solution. Place the conductivity cell in distilled

water and adjust the display to PH 10 with calibration knob. Take a beaker and add 20 ml of

CH3COOH and 20 ml of HCl.Titrate this mixture against 0.1 N NaOH. Now measure initial

conductance of solution. Then 0.1 ml of 0.1 N NaOH is added every time from burette into the

solution and stirred well each time note down the conductance values till the conductance values

decreases and increases considerably.



Graph: y

plot a graph between conductivity on

Y axis and volume of the base added on X axis

.

Vbase(in ml) x

N1V1=N2V2

Volume of NaOH Solution from graph V1 = -- ml

Normality of NaOH Solution N1= --- --N

Volume of mixture of acid solution V2= 20ml

Normality of mixture of acid solution N2 = -----N.

Normality of N2=-------------- N

RESULT: - The Strength of mixture of Acids is __________ N

Sl.No Volume of NaOH Conductivity (ohm-1)

1

2

3

.

.

.

.

30



EXPERIMENT-9

POTENTIOMETRICTITRATION OF STRONG ACID vs. STRONG BASE



Result:



EXPERIMENT-10

POTENTIOMETRICTITRATION OF WEAK ACID vs. STRONG BASE

AIM: - To Determine the concentration of a weak acid by a Potentiometry titration given a

strong base of known concentration.

APPARATUS:- Potentiometer, Pt-electrode, Calomel electrode, Salt bridge, 150 ml beakers,

Stirrer, Pipette, Burette.

CHEMICALS: - 0.1m NaOH, 0.1m CH3COOH, Quinhydrone solid, KCl Solution.

PRINCIPLE: - The quinhydrone electrode is prepared by taking saturated solution of

quinhydrone in a known quantity of strong acid whose concentration is to be determined. This

electrode is combined with thecalomel electrode to make the cell. Pt, Hg,

Hg2Cl2(s)/Saturated//H+/QH2/Pt

In acid medium quinhydrone exist in two forms.

CH3COOH + NaOH → CH3COONa+H2O

As NaOH is added to a solution of H+ ions with quinhydrone the H+ ions are consumed steadily

and the relative concentration of QH2 and Q changes with the titration. At the end point where all

the ions are consumed, QH2 gets completely converted to Q. the electrode potential of the

electrodes is given as per the nearest equation.

Procedure: - Pipettes out 10 ml of the given CH3COOH solution into a clean100ml beaker add a

pinch of quinhydrone and stir it well to make a saturated solution of quinhydrone is H+. dip a

platinum electrode. Take a second beaker with saturated KCl solution in it. Dip the calomel

electrode in it. Connect two beakers with a salt bridge; connect the terminals of the potentiometer

with the two electrodes. Note the emf of the cell. Fill a burette with 0.1 NaOH, add 0.5ml of NaOH

into the beakers containing acid, stir well for equilibrium to establish. Note the emf of the cell

once again. The variation of emf by successive addition of 0.5 ml of NaOH. Each time will be about

10-20mv, as the endpoint approaches, the fall in the emf would increase from 10-20 mv to 40-50

mv. At this stage add NaOH in batches of 0.2 ml and note emf after each addition. At the end point

the emf falls suddenly by about 100-150 mv. Continue the titration with 0.2 ml of NaOH and note

5-6 emf values. Now the variation is emf gets smaller and takes 4-5 emf readings, after the

endpoint by adding batches of 1ml of NaOH each time, tabulate the results.



GRAPH: - Plot a graph of emf Vs volume of NaOH added and a second graph of /E V Vs Volume

of NaOH added. Note the point of Neutralization from both the graph and calculate the cone of

given CH3COOH using the concern of given NaOH as 0.1m

Sl.No Volume of Alkali (ml) Emf (mv)

1

2

3

.

.

.

30



CALCULATION: -

CH3COOH NaOH

1 10V ml 2 _____V (From Graph)

1 ?N 2 0.1N

N1= Normality of CH3COOH N2 = Normality of NaOH

V1= Volume of CH3COOH V2 = Volume of NaOH

N1V1 = N2V2

N1 = N2V2/V1

Concentration of given CH3COOH (1N ) = ____N.

RESULT: - At the Neutralization point 10 ml of given CH3COOH= and concentration of given

CH3COOH =____



EXPERIMENT-11

DETERMINATION OF VISCOCITY BY REDWOOD VISCOMETER



Results:



EXPERIMENT-12

DETERMINATION OF SURFACE TENSION OF LUBRICANTS



Result:



EXPERIMENT-13

Preparation of Aspirin



Result:



EXPERIMENT-14

Preparation of Thiokol rubber



EXPERIMENT-15

ADSORPTION OF ACETIC ACID ON CHARCOAL

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