1

CYCLE I

2

Known Iron(III):

S.NO Volume of Iron(III)

sample in ml Absorbance /

Optical density

1 5

2 10

3 15

4 20

5 25

6 30

3

EXPERIMENT – 1

COLORIMETRIC ESTIMATION OF IRON (III) WITH THIOCYANATE

Aim: To estimate ferric ion using thiocyanate as complexing agent.

Reagents:

1. Ferric ion solution: In a 250 ml volumetric flask 0.432 gm of Ammonium ferric sulphate

is weight. To this 5 ml conc. HCl is add to produce clear solution. The solution make up to

250 ml with distilled water.

2. 10% Potassium thiocyanate (KSCN): 10 gm of KSCN crystals are dissolving in 100 ml

of distilled water.

3. 4N Hydrochloric acid: 18.5 ml of conc. HCl is dilute to 100 ml with distilled water.

4. Working solution: 5 ml of ferric ion solution is dilute to 250 ml in a volumetric flask with

distilled water.

Theory: Ferric ion reacts with thiocyanate to give a series of intensified red color compounds.

These complexes are red and can be formulated as [Fe(SCN)n]2+ where n = 1,2----6. At low

thiocyanate concentration the predominant colour complex is [Fe(SCN)]2+. At very high SCN-

concentration, it is [Fe(SCN)6]3-

Fe3+ + SCN- [Fe(SCN)]2+

Principle:

Iron is one of the many minerals required by the human body. It is used in the

manufacture of the oxygen-carrying proteins, haemoglobin and myoglobin. A deficiency of iron

in the body can leave a person feeling tired and listless, and can lead to a disorder called anemia.

Many of the foods we eat contain small quantities of iron. In this analysis the iron present in an

iron tablet (dietary supplement) or a sample of food is extracted to form a solution containing

Fe3+ (ferric) ions. To make the presence of these ions in solution visible, thiocyanate ions

(SCN−) are added. These react with the Fe3+ ions to form a blood-red coloured complex.

By comparing the intensity of the colour of this solution with the colours of a series of standard

solutions, with known Fe3+ concentrations, the concentration of iron in the tablet or food sample

may be determined. This technique is called colorimetry.

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 (or) . ( . ). 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

4

Unknown Iron(III):

S.NO Volume of Iron(III)

sample in ml Absorbance /

Optical density

1 Unknown-I

2 Unknown-II

5

Procedure:

1. About six 50 ml volumetric flasks are take and into each flask x ml (i.e, x= 5 to 30)of

iron(III) ion solution, 5 ml of 10% thiocyanate solution and 4 ml of 4N HCL are run down

the solution is make up to the mark instantaneously well shake the solution.

2. Add same quantities of 10% thiocyanate solution and 4N HCL to unknown iron (III)

samples and make up to the mark instantaneously well shake the solutions.

3. The optical density (OD) of each sample is measure with 490 nm visible light immediately.

This cyanate complex is unstable, so the readings are taking quickly.

4. A graph is draw with OD along y-axis and volume of the iron (III) along x-axis for known

solutions. The graph is obtained is a straight line.

5. Using optical density values of unknown samples determine the volume of unknown iron

(III) from graph.

Report:

S.NO. Volume of Iron(III)

given (ml)

Volume of Iron(III)

reported (ml)

% Error Marks Signature of the

faculty

1

2

6

Observation and Calculations:

S. No. Temperature

Time required to

flow 50 ml of oil (in

Seconds)

Kinematic Viscosity

(Centistokes)

V = At – B/t

Average

Kinematic

Viscosity

(Centistokes)

The kinematic viscosity of the liquid is given by the formula

V = At - B/t

V = Kinematic viscosity of oil in centistokes

t = Time of flow for 50 ml of oil in seconds

A and B are instrument constants

S. No Type of

equipment Time of flow A value B value

1 Redwood 1 40 to 85 secs 0.264 190

2 Redwood 1 85 to 2000 secs 0.247 65

3 Redwood 2 --- 0.027 20

7

EXPERIMENT – 2

ESTIMATION OF KINEMATIC VISCOSITY OF THE LUBRICATING

OIL

Aim: To determine the kinematic viscosity of given lubricating oil at a given temperature by

using Redwood Viscometer

Principle: The internal drag arises between two successive layers of the liquid is known as

viscosity. Further, the force per unit area required to maintain the velocity gradient by one unit

between two successive layers of one unit length apart is known as viscosity coefficient. High

viscous liquids move slowly while low viscous liquids move fast through a given capillary.

Further, the time required to flow a given volume of liquid through a capillary depends on its

viscosity. Therefore, the viscosity of liquid can be determined by determining the time required

to flow the known volume of liquid through a standard capillary. Viscosity is expressed in poise.

Procedure:

The Redwood viscometer consists of oil cup which is opened at the upper end and it is

fitted with an orifice

It is cleaned thoroughly with suitable solvent and then dried

The orifice is covered with brass ball to stop the flow of oil

The oil cup is placed in the cylindrical copper vessel which serves as water bath

The bath is filled with suitable liquid which has the boiling point higher than the

temperature at which the viscosity of oil to be determined

If the viscosity of the oil is to be determined at 800C or below, the bath is filled with water

The instrument level is adjusted on the tripod stand with the help of the leveling screws

Now the oil cup is filled with oil to be tested carefully up to the level indicated and the

covered with lid

Two thermometers, one is in the oil and the other one is in the liquid (water) are immersed

Similarly two stirrers also placed in the oil and the liquid

One 50 ml flask is kept in position below the jet

Now the oil is heated slowly with constant stirring of oil and the water until it reaches to the

required temperature at which the viscosity of the oil is to be determined

When the temperature of the oil has quite steady and reaches the required temperature, the

brass ball is lifted and simultaneously the stop watch is started.

The oil is allowed to flow through the orifice and collected in the flask

Stop watch is stopped when 50 ml of oil is collected in the flask up to the mark and

immediately the orifice is covered with brass ball to stop the over flow of the oil

The time required to flow the 50 ml of oil is noted

The oil cup is refilled again with oil and same procedure is repeated for five to six times

The viscosity of oil is calculated at given temperature

8

9

Precautions

The oil should be filtered through a 100 mesh wire sieve before testing for its viscosity

Receiving flask should be placed in such a way that the oil jet touches inside layer of the

flask and does not form foaming

Same receiving flask should be used for all readings

After each reading, oil should be completely drained out of the receiving flask and it

should be thoroughly cleaned and dried

Report:

Name of the

Lubricating Oil

Average of kinematic viscosity

(Centistokes)

Marks awarded Signature of the faculty

10

Step-1: Observations & Calculations:

Burette : NaOH Solution

Conical Flask : 20 ml Oxalic Acid

Indicator : Phenolphthalein

End Point : Colour less to Pale pink.

S.No. Volume of Oxalic

acid (v1 ml)

Burette readings (ml) Volume of NaOH Rundown

(v2 ml) Initial Final

1

2

3

4

Calculations:

Oxalic Acid:

M1 = Molarity of Oxalic Acid = 0.05M

V1 = Volume of Oxalic Acid = 20 ml

n1 = Moles of Oxalic Acid = 1 mole

Sodium Hydroxide:

M2 = Molarity of NaOH =?

V2 = Volume of NaOH =

n2 = Moles of NaOH = 2 mole

Molarity of NaOH = ----------------- M

11

EXPERIMENT-3

CONDUCTOMETRIC TITRATION OF ACID BY BASE

Aim: To determine the amount of unknown acid solution with standard base solution by

conductometric method.

Apparatus: Conductivity meter (with cell), burette (10ml), volumetric flask (100 ml), beakers

(100 ml), stirrer / glass rod.

Chemicals: Stock acid solution, 0.05 M oxalic acid in100ml volumetric flask and Stock base

solition.

PRINCIPLE: Conductometric titrations works on the principle of Ohm's law. As current is

inversely proportional to Resistance (R) and the reciprocal of resistance is termed as

Conductance, and its unit is Siemen (mho) cm-1. The electrical conductivity of a solution

depends on the number of ions and their mobility. In Conductometric titrations, the titrant is

added from the burette, and the conductivity readings are plotted against the volume of the

titrant. Upon adding a strong base to the strong acids, the conductance falls until the strong acid

is neutralized then raised. Such a titration curve consists of 2 lines which intersect at a particular

point, known as the End point or Equivalence point. The method can be used for titrating

coloured solutions or homogeneous, which cannot be used with normal indicators.

Strong Acid with a Strong Base:

For example, in the titration of HCl versus NaOH, the addition of a strong base (NaOH)

to a strong acid (Hcl). Before NaOH is added, the conductance is high due to the presence of

highly mobile hydrogen ions. When the base is added, the conductance falls due to the

replacement of hydrogen ions by the added cation as H+ ions react with OH- ions to form

undissociated water. This decrease in the conductance continues till the equivalence point. At the

equivalence point, the solution contains only NaCl. After the equivalence point, the conductance

increases due to the large conductivity of OH- ions.

H2C2O4 + 2 NaOH Na2C2O4 + 2H2O

HCl + NaOH NaCl + H2O

Formula:

Procedure:

Step 1: Standardization of sodium hydroxide by using oxalic acid

1. Rinse and fill the burette with the given NaOH solution

2. Pipette out 20 ml of 0.05 M oxalic acid solution into a clean conical flask

3. Add 1 or 2 drops of phenolphthalein indicator to oxalic acid solution.

4. Titrate the solution against sodium hydroxide solution drop wise with shaking till the

solution changes to pale pin

5. Note the volume of NaOH used. It is the end point.

6. Repeat the titration until the concordant readings are obtained

7. Calculate the molarity of NaOH by using the formula mentioned above

12

Observations and Calculations: Conductometric titration in between HCl and NaOH

Volume of base added Conductance Corrected conductance

C1= C[(v+V)/V]

Calculation of Unknown molarity of HCl solution:

Sodium Hydroxide:

M2 = Molarity of NaOH =

V2 = Volume of NaOH =

n2 = Moles of NaOH = 1 mole

HCl:

M3= Molarity of HCl =?

V3= Volume of HCl = 25 ml

n3 = Moles of HCl = 1 mole

Molarity of HCl = ----------------- M

Amount of HCl = ---------------- grs/l

13

Step 2: Determination of molarity of unknown HCl by using standard NaOH through

conductometric titration

1. In 100 ml beaker take 25ml of given unknown HCl solution and add 25ml of distilled

water. The contents are shaken thoroughly.

2. Now, the conductivity cell is immersed in the beaker and the initial conductance of the

solution is taken by stirring the solution and keeping it constant.

3. Then, 0.5 ml portions of base is added from the burette and stirred well. The conductance

of the solution for each addition is to be noted.

4. The conductivity is corrected by multiplying with the factor [(v+V)/V], where 'v' is the

volume of base added and 'V' is the volume of solution initially taken in the beake

5. Plot the graph with respect to the volume of base consumed versus corrected

conductance. From the intersection point on the graph which gives value represents the

equivalence points of acid and base.

Report:

S.No Given Amount of

unknown Acid

Reported Amount of

unknown Acid

% Error Marks Signature of the

Faculty

1

14

Observations & Calculations:

Step-1: Standardization of EDTA

Burette : EDTA Solution

Concial Flask : 20 ml CaCl2 + 1 ml. of Ammonia Buffer

Indicator : Erichrome Black-T Indicator

End Point : Wine red to Sky Blue.

S.No. Volume of CaCl2

(v1 ml)

Burette readings (ml) Volume of EDTA Rundown

(v2 ml) Initial Final

1

2

3

N1V1 = N2V2

Normality of calcium chloride (N1) = 0.02N

Volume of calcium chloride (V=) = 20 ml

Normality of EDTA (N2) = ?

Volume of EDTA (V2) = volume of EDTA rundown in ml

N2 = N1V1/V2

N2=---------------- N

15

EXPERIMENT NO- 4

DETERMINATION OF HARDNESS OF WATER WITH EDTA

Sample Details: Area: The water sample was collected from ______________(Write the source)

Source: Aim: To estimate the total hardness present in the given water sample.

Apparatus: Burette, Burette Stand, Pipette, Conical Flask, Beaker, Wash Bottle, Glazed tile,

Glass Funnel.

Reagents: EDTA, CaCl2 (0.02N), Ammonia Buffer (pH=10), Erichrome Black-T (EBT)

indicator, Distilled Water.

Principle: In alkaline condition, EDTA reacts with Calcium and Magnesium to form chelated

complex. Ca and Mg develop winered colour with EBT indicator under alkaline condition.

When EDTA is added as titrant, Ca & Mg divalent ions get complexed resulting in a sharp

change from wine red to sky blue colour which indicates end point of the titration. The pH for

the titration has to be maintained at 10.0

complexEBTMg

CaEBT

Mg

Ca pH

10

2

2

Wine red (unstable)

EBTcomplexEDTAMg

CaEDTAcomplexEBT

Mg

CapH

10

Wine red (unstable) Stable Sky Blue

Procedure:

Step-1: Standardization of EDTA

1) Take 20ml. CaCl2 (0.02N) solution in a clean conical flask.

2) To this add 1 ml. of Ammonia Buffer.

3) Add a pinch / 1 (or) 2 drops of EBT indicator.

4) The solution turns to Wine red colour.

5) Titrate with EDTA till the colour changes from Wine red to sky Blue.

6) Note down the volume of EDTA rundown (v2 ml).

7) Repeat the procedure till the concordant readings are obtained.

Step-2: Determination Total Hardness of water sample

1) Take 20ml. water sample in a clean conical flask.

2) To this add 1 ml. of Ammonia Buffer.

3) Add a pinch / 1 (or) 2 drops of EBT indicator.

4) The solution turns to Wine red colour.

5) Titrate with Std. EDTA till the colour changes from Wine red to sky Blue.

6) Note down the volume of EDTA rundown (v3 ml).

16

Step-2: Determination Total Hardness of water sample

Burette : Std. EDTA Solution

Concial Flask : 20 ml water sample + 1 ml. of Ammonia Buffer

Indicator : Erichrome Black-T Indicator

End Point : Wine red to Sky Blue.

S.No. Volume of Water

sample (ml)

Burette readings (ml) Volume of EDTA Rundown

(v3 ml) Initial Final

1

2

3

Calculation of Total Hardness:

= V3 x N2 × 50 ×1000

________________

Volume of Sample

= _____________ mg / litre.

Total Hardness is = _______________ mg / litre or ppm

17

Result:

Source of water sample Hardness (mg/l or ppm) Marks awarded Signature of the faculty

Significance: 1. The permissible limit of total hardness is 200 mg / litre as per W.H.O.

2. Absolutely softwater is tasteless and corrosion in nature.

3. Hardwater causes excessive consumption of soap.

4. Scales are formed in the boilers and reduce the heat efficiency of the boilers.

5. Important in determining the suitability of water for domestic and industrial use.

6. Determination of hardness serves as a basis for routine control of softening process

18

Observations & Calculations:

Step-1: Standardisation of Sodium thiosulphate soludion: Burette : Sodium thiosulphate solution.

Conical flask : Standard K2Cr2O7 + 10% KI + H2SO4

Indicator : 2 ml starch solution

End Point : Blue to colourless

S.No. Volume of Potassium

dichromate (ml)

Burette readings (ml) Volume of Hypo Rundown

(V ml) Initial Final

1

2

3

Potassium dichromate Sodium thiosulphate

N1 = N2 =

V1 = V2 =

N2 = 2

11

V

VN = …………….. N

19

EXPERIMENT NO - 5

ESTIMATE THE AMOUNT OF DISSOLVED OXYGEN BY MODERN

WINKLER’S METHOD

Aim: To find the quantity of Dissolved Oxygen present in given water sample.

Apparatus: BOD Bottles (300ml), Burette, Pipette, Conical Flask, Burette Stand, Wash bottle.

Reagents: 0.02N K2Cr2O7, 48% Manganese Sulphate, Alkali-Iodide-Azide Reagent, Starch

Indicator, Sodium Thiosulphate, Con. Sulphuric Acid, Sodium Hydroxide, sample water,

Distilled water.

Principle: Step-1: As the thiosulphate is a secondary standard solution, it has to be standardized by titrating

against a primary standard dichromate solution iodometrically using starch indicator.

K2Cr2O7 + 6KI + 7H2SO4 Cr2(SO4)3 + 4K2SO4 + 3I2 + 7H2O

Step-2:

Oxygen present in the water sample oxidizes divalent manganese (Mn2+) to its higher oxidation

state (Mn4+) in the presence of Alkali-Iodide-Azide solution. Oxidized manganese liberates

iodine from potassium iodide in acidic medium. The amount of Iodine liberated is equivalent to

dissolved oxygen present in water sample. The liberated iodine is estimated by titrating with

0.025N hypo using starch as an indicator (wrinkler titration).

OHMnOOOHMn 222212 2

(brown ppt)

22

2

2 242 IOHMnHIMnO

6423222 22 OSNaNaIOSNaI

(Sodium tetrathionate)

Formulas:

The strength of sodium thiosulphate N2 = 2

11

V

VN

The amount of dissolved oxygen in the given water sample

= Titre value x conc. of hypo x 8 x 1000 mg/lit.

Volume of sample

Procedure:

Step-1:

Standardisation of Sodium thiosulphate (hypo) solution:

1) Fill the burette with sodium thiosulphate solution.

2) Pipette 10ml of standard potassium dichromate solution into Conical Flask. Add 5 ml of

5 % KI solution and 5 ml of 5N H2SO4 solution.

3) Cover the conical flask with watch glass and put into dark place at 10 min.

4) Titrate the sample solution with thiosulfate until the solution becomes pale yellow.

Introduce 5 drops of starch indicator, and titrate with constant stirring to the

disappearance of the blue colour. Note down the burette reading.

5) Calculate the normality of Sodium thiosulphate.

20

Step-2: Determination of Dissolved oxygen in water sample: Burette : Std. Hypo solution (0.025N)

Concial Flask : 20 ml water sample consists of liberated Iodine

Indicator : 2 ml starch solution

End Point : Blue to colorless.

S.No. Volume of Water sample (ml) Burette readings (ml) Volume of Hypo Rundown

(V3 ml) Initial Final

1

2

3

Dissolved oxygen in the given water sample

= V3 x N2 x 8 x 1000

20

= _______________

= ________ mg /litre

21

Step-2:

Determination of dissolved oxygen present in water sample:

1) Collect 250 ml water sample in a 300ml capacity of BOD bottle.

2) Add 2 ml of manganese sulphate and 2 ml of Alkaline-Iodine-Azide solution.

3) Stopper the BOD bottle immediately.

4) Appearance of brown ppt. indicates the presence of DO.

5) Mix well by inverting the bottle 2 to 3 times and allow the brown ppt. to settle down.

6) Add 2 ml. of conc. H2SO4 solution to dissolve the precipitate.

7) Take 20 ml. of this solution into a clean conical flask.

8) Titrate the liberated iodine with standard hypo solution present in the burette.

9) Add 2 ml of starch solution when the colour of the solution becomes pale yellow. The

solution turns to blue colour.

10) Continue the titration till the blue colour is disappeared.

11) Note the volume of hypo used (V ml)

12) Repeat the titration till the concordant readings are obtained.

13) Calculate the amount of Dissolved Oxygen in the given water sample by using the

formula

Result:

Source of water sample Dissolved oxygen (mg/l) Marks awarded Signature of the faculty

Environmental Significance: 1. The level of dissolved oxygen in fresh water bodies is 8-15 mg/L at 250c

2. If the concentration of dissolved oxygen of water is below 6 ppm, the growth of fish gets

inhibited.

3. The dissolved oxygen is used by microorganisms to oxidise organic matter

4. Oxygen depletion helps in release of phosphates from bottom sediments and causes

eutrophication.

22

23

CYCLE II

24

Step-1: Observations & Calculations:

Burette : NaOH Solution

Conical Flask : 20 ml Oxalic Acid

Indicator : Phenolphthalein

End Point : Colour less to Pale pink.

S.No. Volume of Oxalic

acid (v1 ml)

Burette readings (ml) Volume of NaOH Rundown

(v2 ml) Initial Final

1

2

3

4

Calculations:

Oxalic Acid:

M1 = Molarity of Oxalic Acid = 0.2M

V1 = Volume of Oxalic Acid = 20 ml

n1 = Moles of Oxalic Acid = 1

Sodium Hydroxide:

M2 = Molarity of NaOH =?

V2 = Volume of NaOH =

n2 = Moles of NaOH = 2

Molarity of NaOH = ----------------- M

25

EXPERIMENT-1

pH METRIC TITRATION OF ACID BY BASE

Aim: To determine the Amount of unknown acid solution with standard base solution by pH

metric method.

Apparatus: pH Meter, Glass membrane electrode, 100ml Beaker, Burette, Volumetric Flask,

Glass Rod.

Chemicals: Stock acid solution, 0.2 M oxalic acid and Stock base solution.

Principle: When a glass surface is in contact with a solution it acquires a potential which

depends on H+ ion concentration of solution. This observation which has been made by Haber is

now used as basis of method of determining the pH of a solution where other electrode cannot be

used. The glass electrode has attained much attention in recent years because it can be used

almost in all solutions except those which are strongly acidic or strongly alkaline. It has been

observed that potential difference exists at the interface between glass and solution containing H+

ions. The magnitude of the difference of potential for a given variety of glass varies with its ions

concentration at 250C given by:

E = E0 + 0.0591 log [H+]; E0 = A constant for the given glass electrode.

H2C2O4 + 2 NaOH Na2C2O4 + 2H2O

HCl + NaOH NaCl + H2O

Formula:

Procedure:

Step 1: Standardization of sodium hydroxide by using oxalic acid

1. Rinse and fill the burette with the given NaOH solution

2. Pipette out 20 ml of 0.2 M oxalic acid solution into a clean conical flask

3. Add 1 or 2 drops of phenolphthalein indicator to oxalic acid solution.

4. Titrate the solution against sodium hydroxide solution drop wise with shaking till the

solution changes to pale pin

5. Note the volume of NaOH used. It is the end point

6. Repeat the titration until the concordant readings are obtained

7. Calculate the molarity of NaOH by using the formula mentioned above

Step 2: Determination of molarity of unknown HCl by using standard NaOH through pH

metric titration

1. Rinse and fill the burette with standard NaOH solution

2. Now you collect unknown acid in 100 ml volumetric flak and makeup with distilled water

26

Step-2: Observations and Calculations: pH Metric titration in between HCl and NaOH

VOLUME OF NaOH

ADDED

pH

Calculation of unknown molarity of HCl solution:

Sodium Hydroxide:

M2 = Molarity of NaOH =

V2 = Volume of NaOH =

n2 = Moles of NaOH = 1

HCl:

M3= Molarity of HCl =?

V3= Volume of HCl = 5ml

n3 = Moles of HCl = 1

Molarity of HCl = ----------------- M

Amount of HCl = ---------------- grs/l

27

3. Take 5ml of given unknown HCl solution into 100ml beaker and add 45ml of distilled

water. The contents are shaken thoroughly.

4. The glass membrane electrode is dipped into the beaker containing the solution.

5. Initially at “0” Burette reading of NaOH solution, pH of the unknown HCl solution can be

measured.

6. Then 0.5 ml of base is added from the burette to the acid solution and on stirring

thoroughly the pH of the resultant solution can be noted.

7. The pH is noted every time by the addition of 0.5 ml base and finally you observe the pH

jump is between V1 and V2 ml. After pH jump you need to note about 10 readings.

8. Plot the graph with the volume of base on X - axis versus pH on Y-axis. Identify the

suitable jump which changes the medium from acidic pH to Basic pH.

9. Take the average in-between the jump values and draw a line which intercepts X axis. The

intersection point gives value of the equivalence point (End point) of acid and base

Report:

S.No Given Amount of

unknown Acid

Reported Amount of

unknown Acid

% Error Marks Signature of the

Faculty

1

28

Step-1: Observations & Calculations:

Burette : NaOH Solution

Conical Flask : 20 ml Oxalic Acid

Indicator : Phenolphthalein

End Point : Colour less to Pale pink.

S.No. Volume of Oxalic

acid (v1 ml)

Burette readings (ml) Volume of NaOH Rundown

(v2 ml) Initial Final

1

2

3

4

Calculations:

Oxalic Acid:

M1 = Molarity of Oxalic Acid = 0.05M

V1 = Volume of Oxalic Acid = 20 ml

n1 = Moles of Oxalic Acid = 1 mole

Sodium Hydroxide:

M2 = Molarity of NaOH =?

V2 = Volume of NaOH =

n2 = Moles of NaOH = 2 mole

Molarity of NaOH = ----------------- M

29

EXPERIMENT-2

CONDUCTOMETRIC TITRATION OF AN ACID MIXTURE BY BASE

Aim: To determine the amount of unknown acids with standard base solution by conductometric

titration.

Apparatus: Conductivity meter (with cell), burette (10ml), volumetric flask (100 ml), beakers

(100 ml), stirrer / glass rod.

Chemicals: HCl solution, CH3COOH solution, 0.05 M oxalic acid and NaOH solution.

Principle: Conductometric titrations works on the principle of Ohm's law. As current is

inversely proportional to Resistance (R) and the reciprocal of resistance is termed as

Conductance, and its unit is Siemen (mho) cm-1. The electrical conductivity of a solution

depends on the number of ions and their mobility. In Conductometric titrations, the titrant is

added from the burette, and the conductivity readings are plotted against the volume of the

titrant. Upon adding a strong base to the strong acid and weak acid mixture, the conductance falls

until the strong acid is neutralized then raised slightly until weak acid neutralized then raised

rapidly. Such a titration curve consists of 3 lines which intersect at two particular points, known

as the End points or Equivalence points. First equivalence point corresponds to strong acid and

strong base titration. Second equivalence point corresponds to weak acid and strong base

titration. The method can be used for titrating coloured solutions or homogeneous, which cannot

be used with normal indicators.

Theory: In the titration addition of a strong base (NaOH) to mixture of a strong acid (HCl) and

weak acid (CH3COOH). Before NaOH is added, the conductance is high due to the presence of

highly mobile hydrogen ions. When the base is added, the conductance falls due to the

replacement of hydrogen ions by the added cation as H+ ions react with OH- ions to form

undissociated water. This decrease in the conductance continues till the first equivalence point.

After the first equivalence point, the conductance increases slightly due to neutralization of

CH3COOH and formation of CH3COONa and finally increased rapidly due to complete

neutralization of CH3COOH and excess addition of NaOH.

H2C2O4 + 2 NaOH Na2C2O4 + 2H2O

HCl + NaOH NaCl + H2O

CH3COOH + NaOH CH3COONa + H2O

30

Observations and Calculations: Conductometric titration in between mixture of HCl&

CH3COOH and NaOH

Volume of NaOH added Conductance Corrected conductance

C1= C[(v+V)/V]

31

Formula:

; ;

Procedure:

Step 1: Standardization of sodium hydroxide by using oxalic acid

1. Rinse and fill the burette with the given NaOH solution

2. Pipette out 20 ml of 0.05 M oxalic acid solution into a clean conical flask

3. Add 1 or 2 drops of phenolphthalein indicator to oxalic acid solution.

4. Titrate the solution against sodium hydroxide solution drop wise with shaking till the

solution changes to pale pin

5. Note the volume of NaOH used. It is the end point.

6. Repeat the titration until the concordant readings are obtained

7. Calculate the molarity of NaOH by using the formula mentioned above

Step 2: Determination of molarity of unknown HCl and CH3COOH by using standard

NaOH through conductometric titration

1. In 250 ml beaker take 25ml of given unknown HCl solution and 25ml of given unknown

CH3COOH solution add 50ml of distilled water. The contents are shaken thoroughly.

2. Now, the conductivity cell is immersed in the beaker and the initial conductance of the

solution is taken by stirring the solution and keeping it constant.

3. Then, 0.5 ml portions of base is added from the burette and stirred well. The conductance

of the solution for each addition is to be noted.

4. The conductivity is corrected by multiplying with the factor [(v+V)/V], where 'v' is the

volume of base added and 'V' is the volume of solution initially taken in the beake

5. Plot the graph with respect to the volume of base consumed versus corrected conductance.

From the intersection points on the graph which gives value represents the equivalence

points of acid and base.

32

Calculation of Unknown molarity of HCl solution:

Sodium Hydroxide:

M2 = Molarity of NaOH =

V2 = Volume of NaOH = n2 = Moles of NaOH = 1 mole

HCl:

M3= Molarity of HCl =?

V3= Volume of HCl = 25 ml

n3 = Moles of HCl = 1 mole

Molarity of HCl = ----------------- M

Amount of HCl = ---------------- gm/l

Calculation of Unknown molarity of CH3COOH solution

Sodium Hydroxide:

M2 = Molarity of NaOH =

V2 = Volume of NaOH = n2 = Moles of NaOH = 1 mole

CH3COOH:

M3= Molarity of CH3COOH =?

V3= Volume of CH3COOH = 25 ml

n3 = Moles of CH3COOH = 1 mole

Molarity of CH3COOH = ----------------- M

Amount of CH3COOH = ---------------- gm/l

33

Report:

S.No Given Amount of HCl &

CH3COOH

Reported Amount of HCl

& CH3COOH

% Error Marks Signature of

the Faculty

1

2

34

KNOWN:

Pilot Titration Accurate Titration

S.NO. Volume of K2Cr2O7 Potential in volts S.NO. Volume of K2Cr2O7 Potential in volts

35

EXPERIMENT NO-3

POTENTIOMETRIC TITRATION OF IRON (II) WITH POTASSIUM

DICHROMATE

Aim: To determine the concentration of Ferrous ammonium sulphate using standard potassium

dichromate following a potentiometric method.

Apparatus: Potentiometry, Standard calomel electrode,

Solutions required: 0.1N K2Cr2O7, 0.1N Ferrous ammonium sulphate and 1:1 H2SO4

General Principle:

Potentiometric Titrations: Potentiometric titrations involve the measurement of the potential of

a suitable indicator electrode with respect to a reference electrode as a function of titrant volume.

Potentiometric titrations provide more reliable data than data from titrations that use chemical

indicators and are particularly useful with colored or turbid solutions and for detecting the

presence of unsuspected species.

A typical cell for potentiometric analysis consists of a reference electrode, an indicator electrode

and a salt bridge. This cell can be represented as

A reference electrode, Eref, is a half-cell having a known potential that remains constant at

constant temperature and independent of the composition of the analyte solution. The reference

electrode is always treated as the left-hand electrode in potentiometric measurements. Calomel

electrodes and silver/silver chloride electrodes are types of reference electrodes. An indicator

electrode has a potential that varies with variations in the concentration of an analyte. Most

indicator electrodes used in potentiometry are selective in their responses. Metallic indicator

electrode and membrane electrodes are types of indicator electrodes. The third component of a

potentiometric cell is a salt bridge that prevents the components of the analyte solution from

mixing with that reference electrode. A potential develops across the liquid junctions at each end

of the salt bridge. The junction’s potential across the salt bridge, Ej, is small enough to be

neglected. The potential of the cell is given by the equation;

Ecell= Eind – Eref + Ej

36

UNKNOWN:

Pilot Titration Accurate Titration

S.NO. Volume of K2Cr2O7 Potential in volts S.NO. Volume of K2Cr2O7 Potential in volts

Calculation:

Known: 20 ml of Fe(II) solution consume x ml of Cr(VI)

Unknown: x ml of Cr(VI) solution consume 20 ml of Fe(II) solution

y ml of Cr(VI) solution consume ? ml of Fe(II) solution

? ml = y×20/x

20 ml of Fe(II) solution contains = ? ml of Iron

100 ml of Fe(II) solution contains = ?? ml of Iron

?? = ?×100/20

37

Procedure:

1. 20.00 ml of ferrous ammonium sulphate is transferred to a 100 ml beaker by means of

burette.

2. To this 15.00 ml of distilled water and 5.00 ml of 1:1 H2SO4 are added and the contents

are shaken thoroughly.

3. The platinum electrode placed in the beaker the being connected to the positive end of the

potentiometer.

4. After measuring the emf of the solution in the beaker, the standard K2Cr2O7 add from the

burette in one ml portion while stirring the content in the beaker with glass rod and

corresponding e.m.f are note down.

5. At a certain point a sudden raise in potential is observed this shows that the end point is

in between these additions where the jump is observed thus titrated readings are called

point readings by which are can get the end point approximately.

6. Again taking the same content in the beaker and titrated with standard K2Cr2O7 in the

same manner by the addition of 1 ml dichromate solution up to the jump reading. But in

between point readings add only 0.1 ml dichromate and note down potential readings.

7. After the end point 4-5 ml of dichromate is added in ml portion and the corresponding

readings are note down.

8. The plot is made between the e.m.f values as ordinate (Y-axis) and volume of dichromate

added as the abscissa (X-axis). The volume of dichromate corresponding to the point of

inflection gives the equilibrium point for the titration.

9. The same procedure is repeat for the unknown solution of Fe(II). From their equilibrium

points the unknown volume is calculate from this its concentration can also calculate.

Report:

S.NO. Volume of Fe(II) % Error Faculty

Signature Given Reported

38

Observation and Calculation:

Step-1: Standardization of KOH Solution.

Burette : KOH solution

Conical flask : 20 ml. of Oxalic Acid

Indicator : Phenolphthalein

End point : Colourless to pink.

S. No. Vol. of Oxalic Acid

Burette readings Vol. of KOH

rundown Initial Final

Normality of KOH N2 = 2

11

V

VN

N1 = Normality of oxalic acid

V1 = Volume of the oxalic acid

V2 = Volume of the KOH

39

EXPERIMENT NO-4

DETERMINATION OF ACID NUMBER OF LUBRICATING OIL

Aim: To determine the Acid number of lubricating oil.

Apparatus: 50 ml burette, 20ml pipette, 250 ml conical flask, 100ml beaker, 250 ml beaker, 50

ml beaker and 50 ml measuring jar.

Chemicals: KOH solution, 0.02N oxalic acid, Oil sample, Phenolphthalein indicator, Ethyl

alcohol.

Principle:

The Acid number of lubricating oil is defined as the number of milligrams of potassium

hydroxide required to neutralize the free acid present in 1 g of the oil sample. In good lubricating

oils, the acid number should be minimum (<0.1). Increase in acid value should be taken as an

indicator of oxidation of the oil which may lead to gum and sludge formation besides corrosion.

Since free fatty acids present in the oil react with base, their quantity can be estimated by

titrating the known weight of the oil sample dissolved in a suitable solvent with a standard

alcoholic solution of KOH to a definite end point

RCOOH + KOH RCOOK + H2O

Procedure:

Step 1: Standardization of KOH

20 ml standard oxalic acid solution is pipette out into a 250 ml of conical flask and few

drops of Phenolphthalein indicator is added.

The above solution is titrated with standard KOH solution taken in the burette until the

solution changes from colorless to light pink colour

The same procedure is repeated until any two readings coincide

The concentration of KOH is calculated.

40

Step-2: Determination of Acid Number:

Burette : Std. KOH solution

Conical flask : 1gm. of lubricating oil + 5 ml of alcohol.

Indicator : Phenolphthalein

End point : Colourless to pink.

S. No. Vol. of

lubricating oil

Burette readings Vol. of KOH

Initial Final

Acid Number of given oil sample is

(mg of KOH required to neutralize the acid present in 1 gm of oil) =

1000

100..2 KOHofVolKOHofwtEqN

N2 = Normality of KOH

Eq. wt of KOH = 56.01

Vol. of KOH = titer value in the above titration

=------------------------

41

Step 2: Determination of Acid Number of given oil sample

1 gram (1.1 ml) of oil sample is taken in a 250 ml conical flask and dissolved in 5 ml of

Ethyl alcohol.

One or two drops of Phenolphthalein indicator is added and the solution is titrated with

KOH taken in the burette until the solution changes from colorless to light pink

The same procedure is repeated until any two readings coincide

The Acid Number of oil sample is calculated.

Result:

Name of

lubricating

oil sample

Weight of oil

sample

Acid number Marks awarded Signature of the faculty

42

Step 1: Standardization of KMnO4

S. No. Vol. of H2C2O4 Burette Readings

Vol. of KMnO4 Initial Final

Concentration of KMnO4 is calculated by using the formula

NKMnO4 =

4

422422

KMnOV

VNOCHOCH

43

EXPERIMENT – 5

ESTIMATION OF PERCENTAGE OF PURITY OF PYROLUSITE ORE

Aim: To determine the amount of manganese dioxide present in a given pyrolusite ore sample.

Principle:

Pyrolusite is one of the manganese ores. Manganese is present in the ore as its oxidised form,

manganese dioxide. It is widely used in industries for making of manganese alloys. Pyrolusite

powder is boiled with excess of known oxalic acid in the presence of conc. sulphuric acid to

reduce the Mn4+ in MnO2 to Mn2+. The excess of oxalic acid is back titrated with standard

potassium permanganate solution.

MnO2 + H2C2O4 + H2SO4 MnSO4 + 2H2O + 2CO2

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

Required Solutions:

0.25 N stock oxalic acid: Nearly 3.2g (=W) of oxalic acid is weighed and dissolved in 250

ml (=V) of water in a volumetric flask.

Vacid oxalic ofEq.wt

1000acid oxalicStock

WN

0.05 N oxalic acid solution: 20 ml (=Vx) of stock oxalic acid solution is taken in a 100 ml of

volumetric flask and the solution is made upto the mark. The concentration of the solution is

calculated by the formula.

)100(V acid Ooxalic

acid OoxalicStock

acid Ooxalicml

VNN x

0.05 N KMnO4 solution: Nearly 0.4gms of KMnO4 is weighed and dissolved in a small

portion of water, it is boiled for 5mins and filtered by using glass wool. The solution is made

upto 250ml. As KMnO4 cannot be obtained in pure form, it is standardized with standard

oxalic acid solution.

Conc. H2SO4 is required

44

Step 2: Preparation & Standardization of pyrolusite sample Solution

S. No. Vol. of

Sample

Burette Readings Vol. of KMnO4

Initial Final

Concentration of unreacted oxalic acid

acid Oxalic

44acid Oxalic

V

VNN

KMnOKMnO

Amt of oxalic acid unreacted (gr) = W2 = 1000

Vacid oxalic of Eq.wt. 2acid Oxalic N

Amt of oxalic acid taken (gr) = W3 = 1000

V acid oxalic of Eq.wt. 1acid OxalicStock N

Amt of oxalic acid reacted = W4 = W3-W2

Amt of MnO2 present in pyrolusite = 42

acid Oxalic of Wt.M.

MnO of Wt.Mol.W

% of MnO2 is pyrolusite = 100 sample of Wt.

MnO of Wt. 2

45

Procedure:

Step 1: Standardization of KMnO4:

20ml of the 0.05N oxalic acid solution is taken in a conical flask and add 5 ml of conc.

H2SO4 and dilute the mixture to 100ml.

The mixture is heated to 70-80oC

The solution is titrated with KMnO4 solution to be standardized in hot condition until the

solution becomes light pink.

The same procedure is repeated till two successive readings are coinciding.

Step 2: Preparation & Standardization of pyrolusite sample Solution

Nearly 0.6 g (=W1) of powdered pyrolusite sample is weighed accurately and transferred into

a 250 ml conical flask.

Exactly 50 ml (=V1) of stock oxalic acid is added with the help of burette.

10 ml of concentrated H2SO4 is also added.

Now the mixture is boiled gently to reduce MnO2 to MnSO4 until no black particles of

pyrolusite ore remain undissolved.

The mixture is cooled and diluted to 250 ml (=V2) in a volumetric flask.

20 ml of this solution is taken in a conical flask and diluted to 100 ml

5 ml of concentrated H2SO4 is added and heated to 70O-800C.

Now it is titrated with standard KMnO4 solution until light pink colour is formed.

The same procedure is repeated till two successive readings coincide.

The concentration of unreacted oxalic acid is calculated.

The percentage purity of pyrolusite is calculated.

Report:

Substance Percentage Reported Percentage Given Error

46

47

CYCLE III

48

Step-1: formation of o,p methyl phenol:

Step-2; formation of novalac:

Step-3: formation of bakelite:

49

EXPERIMENT – 1

PREPARATION AND CALCULATION OF THE YIELD OF PHENOL-

FORMALDEHYDE RESIN

Aim: To prepare the phenol – formaldehyde resin

Principle:

Phenol formaldehyde resins (PF) include synthetic thermosetting resins such as bakelite

obtained by the reaction of phenols with formaldehyde. Phenol-formaldehyde resins are formed

by a step-growth polymerization reaction that can be either acid- or base-catalysed.

Phenol is reactive towards formaldehyde at the ortho and para sites (sites 2, 4 and 6)

allowing up to 3 units of formaldehyde to attach to the ring. The initial reaction in all cases

involves the formation of ortho & para hydroxymethyl phenols. The ortho hydroxymethyl phenol

undergoes linear polymerization to form novalac which is fusible and soluble in most of the

organic solvents. Novolacs are phenol-formaldehyde resins made where the molar ratio of

formaldehyde to phenol of less than one. Hexamethylene tetramine or "hexamine" is a hardener

that is added to crosslink novolac. At ≥180 °C, the hexamine forms crosslink’s to form

methylene and dimethylene amino bridges. Base-catalysed phenol-formaldehyde resins are made

with a formaldehyde to phenol ratio of greater than one (usually around 1.5). These resins are

called resols.

When the molar ratio of formaldehyde: phenol reaches one, every phenol is linked

together via methylene bridges, generating one single molecule, and the system is entirely

crosslinked. In bakelite, this ratio is greater than one, and so it is very hard

Procedure:

5.0 ml of phenol is weighed and transferred into a clean and dried 250 ml beaker.

7 ml of formaldehyde solution is added carefully. (Caution : Avoid the inhaling the

vapours and spilling of it on body)

5.0 ml of glacial acetic acid and one or two spatula of hexamine (hexamethylene

tetramine) are added

The contents of the beaker are heated gently in a water bath.

The beakers is removed from the water bath and add conc. hydrochloric acid slowly

drop-wise with constant stirring.

After the addition of hydrochloric acid a white substance precipitates first. Finally, a pink

colored plastic clump is formed at the bottom of the beaker while stirring.

The plastic clump is now washed with distilled water for several times and then dried in a

oven

Now the sample is weighed and its weight is reported

50

51

Precautions:

Formaldehyde solution 37 % is very toxic by inhalation, ingestion and through skin

absorption. Readily absorbed through skin. Probable human carcinogen. Mutagen. May

cause damage to kidneys, allergic reactions, sensitization and heritable genetic damage.

Phenol is acute poisoning by ingestion, inhalation or skin contact may lead to death.

Phenol is readily absorbed through the skin. Highly toxic by inhalation.

Safety glasses and protective gloves required. The experiment should be performed under

a portable fume cupboard giving all-round visibility

Report:

Amount of Resin

formed

Marks awarded Sign. of the faculty

52

Observations & Calculations:

Water

Time of flow Average time

Benzene /

Aniline/

Toulene

Time of

flow

Average

time

Densities of different organic liquids:

Name of the Organic

Liquid

Density in gr./cc

BENZENE 0.8737

TOULENE 0.8625

ANILINE 1.02

Calculations:

l

w

l

w

l

w

t

t.

?...................l

53

EXPERIMENT – 2

ESTIMATION OF VISCOSITY OF AN ORGANIC SOLVENT BY USING

OSTWALD VISCOMETER

Aim: To determine the coefficient of viscosities of various liquids like benzene, Aniline and

acetic acid.

Principle: Resistance to flow of a liquid is known as viscosity. The retarding force is

proportional to the area of contact and the velocity gradient. The proportionality constant ‘η’ is

the coefficient of viscosity, and is characteristic of a liquid. When a liquid flows through a

capillary tube, η = πρr4t/8Vl, where ‘ρ’ is the density of liquid, ‘r’ is the radius of the tube, ‘t’ is

the time of flow, ‘l’ is the length of the capillary tube and V is the volume of liquid. This is

called absolute viscosity determination. But if the same volumes of two liquids are allowed to

flow through the same tube, then we have the relation.

l

w

l

w

l

w

t

t.

ηw =Viscosity of water; ηl = Viscosity of given organic liquid;

ρw= Density of water; ρl= Density of given organic liquid

tw= Time of flow of water; tl= Time of flow of given organic liquid

If the viscosity of one liquid is known, then the other can be calculated. An Ostwald’s viscometer

is used to determine relative viscosity of liquids

Procedure:

1. An Ostwald viscometer is cleaned by rinsing three times with small volumes of acetone and

dried.

2. The lower bulb is filled with distilled water and clamped vertically.

3. A rubber bulb is attached to the tip of the narrow limb and the liquid drawn up to a level

much above the upper mark.

4. The rubber bulb is removed and the liquid allowed to flow down freely.

5. A stop watch is started just as the liquid meniscus passes the upper mark and stopped when it

passes the lower mark.

6. The time of flow ‘tw’ is noted. Density of water is 0.9971 gr./cc and ‘ηw’ for water is 8.94

milli poise at 250C.

7. The viscometer is again cleaned and dried as before. It is then filled with the experimental

liquid (Benzene, Toluene, Aniline and Glacial acetic acid). 8. Time of flow ‘tl’ is determined as in the case of water. The densities of the liquids may either

be determined or taken from literature. 9. The coefficient of viscosity ‘ηl’ of the liquid can be calculated.

54

55

Result:

Name of the

Given Organic

solvent

Coefficient of viscosity (m.p) Marks awarded Signature of the faculty

56

Observation:

Sl.No. Source of Water

Sample

Turbidity (in NTU)

1

2

3

4

5

57

EXPERIMENT-3

NEPHELOMETRIC DETERMINATION OF TURBIDITY PRESENT IN THE

GIVEN WATER SAMPLE

Aim: To determine the turbidity of the various water samples.

Apparatus: Nephelometer, Test tubes

Chemicals: Standard turbidity suspensions 400 NTU, 100 NTU, 40 NTU, 20 NTU, and 10

NTU, Distilled water, sample water.

Principle: Turbidity is an equal property of sample that cause light to be absorbed and scattered

rather than thransmitted through the sample. It depends on the amount and particle size of the

suspended matter present in water. The method of determination is based on a comparison of the

internsity of the light scattered by the sample under defined conditions with the intensity of light

scattered by a standard reference suspension. The higher the intensity of scattered light, the

higher the turbidity. It is expressed as NTU. This can be measured by Nephelometer.

Procedure:

1) Connect the three pin plug to a main outlet and switch the instrument to ON position. Let

the instrument be warm up for about 2 to 3 minutes.

2) Set the Mode Selector to the 100 NTU. Take 4 to 5 ml distilled water in a test tube and

insert into cuvette holder. Adjust the Set Zero control to obtain zero reading on DPM

display.

3) Fill up another tet tube with 4 to 5 ml of 100 NTU standard suspension and insert in the

cuvette holder. Adjust the level control such that the DPM display reads a value of 100

NTU. Now the instrument is calibrated for the 100 NTU range, and any suspension in

this range can be measured.

4) Fill up another test tube with 4 to 5 ml of the unknown turbidity sample and insrt in the

cuvette holder. Note the reading on the DPM display. This reading directly corresponds

to the turbidity of the unknown sample in NTU.

5) Adjust the Mode selector to 40, 20 and 10 NTU range and repeat the procedure for any

unknown solution whose turbidity is expected to be within 40, 20 and 10 NTU

respectively.

Result:

Source of water sample Turbidity (NTU) Marks awarded Signature of the faculty

58

OBSERVATION TABLE: Determination of Flash point and Fire point:

Sl.No. Temperature in Degree Celcius Inference

59

EXPERIMENT – 4

DETERMINATION OF FLASH AND FIRE POINTS OF GIVEN OIL

SAMPLES

Aim: To determine the flash and fire point of a given fuel oil.

Apparatus required: Pensky marten’s apparatus, thermometer and beaker

Oli used: Kerosene / Diesel

Significance of experiment:

In industries oils are generally used for combustion, lubricant and cooling purposes. To

use oil for any purpose, we are required to know the flash point and fire point, to eliminate the

fire hazards and to set working temperature conditions. Flash point is also used as a means to

identify the presence of impurities in the lubricant oil.

Theory:

Flash point: it is the lowest temperature at which the oil gives off enough vapors to ignite for a

moment, when a test flame is brought near it.

Fire Point: It is the lowest temperature at which the oil burns continuously for atleast 5 seconds

when a test flame is brought near it.

DESCRIPTION OF THE APPARATUS: This is the closed cup apparatus and it consists the following given parts. The oil cup is

cylindrical vessel with lid. It is fitted on the outside with a flat circular flange. There are three

ports cut in the lid. The central one for admitting test flame and one on either side of it for

observing the flash over the lid. There is a shutter, which opens the port on the lid for

introducing test-flame over the oil surface. A stirrer is placed in the cup for stirring the oil to get

uniform temperature.

PROCEDURE: 1) Fill the oil cup to the mark, place the cover on the cup, then start heating.

2) Stirr the oil to main the uniform temperature.

3) Apply the test flame in the oil cup for every 5 seconds.

4) Repeat the same til the momentary flash occurs, then note the temperature as a flash

point.

5) Rise the temperature slowly and check for fire point for every degree rise of temperature.

Note the temperature as fire point, when oil glows for more than five seconds.

60

61

PRECAUTIONS: 1) Thermometer should not touch the bottom of the cup.

2) The energy regular should be adjusted so that the heating of oil is uniform slow and

steady.

3) After every trial allow the cup and thermometer to reach room temperature before

introducing the next sample.

4) The bulb of the thermometer should dip inside the oil sample.

RESULT:

Name of the

Given oil sample

Flash point(0C) Fire point (0C) Marks awarded Signature of the faculty

62

OBSERVATION TABLE: Determination of Flash point and Fire point:

Sl.No. Temperature in Degree Celcius Inference

63

CLEVELANDS APPARATUS

Aim: to determine the flash and fire point of a given fuel oil

Apparatus required: Clevelands apparatus, thermometer and beaker

Oli used: Kerosene / Diesel.

Significance of experiment:

In industries oils are generally used for combustion, lubricant and cooling purposes. To

use oil for any purpose, we are required to know the flash point and fire point, to eliminate the

fire hazards and to set working temperature conditions. Flash point is also used as a means to

identify the presence of impurities in the lubricant oil.

Theory:

Flash point: it is the lowest temperature at which the oil gives off enough vapors to ignite for a

moment, when a test flame is brought near it.

Fire Point: It is the lowest temperature at which he oil burns continuously for atleast 5 seconds

when a test flame is brought near it.

DESCRIPTION OF THE APPARATUS: The clevelands apparatus consists of an open cup to which a handle is fitted. There is a

mark for the maximum level of oil inside the cup. The cup is heated electrically by separate

arrangement of integrated device consist of a heater and power supply regulator. The test flame

is supplied over the surface of oil by simple mechanism. The thermometer dipped manually in

the oil to read the temperature.

PROCEDURE: 1) Fill the oil cup to the mark, place the cover on the cup, then start heating.

2) Stirr the oil to main the uniform temperature.

3) Apply the test flame in the oil cup for every 5 seconds.

4) Repeat the same til the momentary flash occurs, then note the temperature as a flash

point.

5) Rise the temperature slowly and check for fire point for every degree rise of temperature.

6) Note the temperature as fire point, when oil glows for more than five seconds.

7) After reaching the fire point, put off the heater.

PRECAUTIONS: 1) Thermometer should not touch the bottom of the cup.

2) The energy regular should be adjusted so that the heating of oil is uniform slow and

steady.

3) After every trial allow the cup and thermometer to reach room temperature before

introducing the next sample.

4) The bulb of the thermometer should dip inside the oil sample.

5) Breathing over the surface of the oil should be avoided.

RESULT:

Given oil sample Flash point(0C) Fire point (0C) Marks awarded Signature of the faculty

64

Step-1: Observations & Calculations:

Burette : NaOH Solution

Conical Flask : 20 ml Oxalic Acid

Indicator : Phenolphthalein

End Point : Colour less to Pale pink.

S.No. Volume of Oxalic

acid (v1 ml)

Burette readings (ml) Volume of NaOH Rundown

(v2 ml) Initial Final

1

2

3

4

Calculations:

Oxalic Acid:

M1 = Molarity of Oxalic Acid = 0.2M

V1 = Volume of Oxalic Acid = 20 ml

n1 = Moles of Oxalic Acid = 1

Sodium Hydroxide:

M2 = Molarity of NaOH =?

V2 = Volume of NaOH =

n2 = Moles of NaOH = 2

Molarity of NaOH = ----------------- M

65

EXPERIMENT-5

POTENTIOMETRIC DETERMINATION OF STRONG ACID USING

STRONG BASE

Aim: To determine the neutralization point in the potentiometric titration of strong acid vs strong

base.

Apparatus: Potentiometer bridge, Saturated calomel electrode, platinum electrode, 100ml

Beaker, Burette, Volumetric Flask, Glass Rod.

Chemicals: 0.1 M Hcl, 0.1 M NaOH , 0.1M Oxalic acid and Phenolpthalein indicator.

Principle: In the titration of 0.1M HCl with 0.1M NaOH on addition of the alkali, there is

variation in the concentration of H+ ions, there variations in the concentration of H+ ions i.e. PH

is followed potentiometrically using Quinhydrone (reversible to hydrogen ion) as, the indicator

electrode in the HCl solution and coupling it with saturated calomel electrode (reference

electrode) since the potential of the lather remains constant, the emf of the cell will vary only

with PH of HCl solution. Therefore by measuring this emf act each stage of the titration and

plotting it against the volume of base, we can deduce the equivalence point from the plot. At the

end point, the emf increases at once which is clearly detected in the of graph.

Cell reaction is: Hg / Hg2Cl2 (s).KCl(saturated solution)(s) // H+ , QH2/PtFormula:

Procedure:

Step 1: Standardization of sodium hydroxide by using oxalic acid

8. Rinse and fill the burette with the given NaOH solution

9. Pipette out 20 ml of 0.1 M oxalic acid solution into a clean conical flask

10. Add 1 or 2 drops of phenolphthalein indicator to oxalic acid solution.

11. Titrate the solution against sodium hydroxide solution drop wise with shaking till the

solution changes to pale pin

12. Note the volume of NaOH used. It is the end point

13. Repeat the titration until the concordant readings are obtained

14. Calculate the molarity of NaOH by using the formula mentioned above

66

Step-2: Observations and Calculations: pH Metric titration in between HCl and NaOH

VOLUME OF NaOH

ADDED

EMF (mv)

1ml

2ml

3ml

4ml

5ml

6ml

7ml

8ml

Calculation of unknown molarity of HCl solution:

Sodium Hydroxide:

M2 = Molarity of NaOH =

V2 = Volume of NaOH =

n2 = Moles of NaOH = 1

HCl:

M3= Molarity of HCl =?

V3= Volume of HCl = 20ml

n3 = Moles of HCl = 1

Molarity of HCl = ----------------- M

Amount of HCl = ---------------- grs/l

67

Step 2: Determination of Strength of unknown HCl by using standard NaOH through

Potentiometric titration

1. Pipette out 20ml of 0.1M HCl solution into beaker and saturate it with quinhydrone.

2. Dip the indicator electrode (platinum electrode) and connect the indicator electrode and

saturated calomel electrode (reference electrode) to the potentiometer.

3. The two half cells are connected by means of a salt bridge.

4. The potentiometer is standardized and used for measuring the emf directly.

5. Take 20 ml of HCl solution in the beaker and add 1 ml of 0.1M NaOH from the burette

every time.

6. Shake well after each addition and measure the cell emf.

7. From this rough titration find out the approximate volume needed for the end points. Now a

fair titration is repeated by adding volumes of 1ml alkali.

8. Subsequent additions are made in steps of 1or 2 ml of alkali. Then plot a graph between the

measured emf on Y-axis and volume of alkali on X-axis.

Report:

S.No Given Amount of

unknown Acid

Reported Amount of

unknown Acid

% Error Marks Signature of the

Faculty

1

68

69

TOPIC BEYOND THE

SYLLABUS

70

Step1: Observations and calculations

Preparation of standard solution of Disodium salt of EDTA

Weight of weighing bottle + EDTA salt (W1) = ----------------- g

Weight of empty weighing bottle (W2) = ----------------- g

Weight of EDTA transferred (W1 – W2) = ---------------- g

Molarity of EDTA = Weight of EDTA taken X 4

Mol. Weight of EDTA(372)

71

EXPERIMENT NO 1

DETERMINATION OF CALCIUM OXIDE IN THE GIVEN SAMPLE OF

CEMENT SOLUTION

Aim: To determine the percentage of calcium oxide in the given cement solution using standard

Std EDTA.

Principle:

Cement contains compounds of Calcium, Aluminium, Magnesium, Iron and insoluble silica.

When dissolved in acid , silica remains undissolved. On treating with ammonia, aluminium and

iron can be precipitated as their hydroxides and separated. The provided cement solution

contains calcium and magnesium ions. The constituents of Portland cement are CaO (60-67%),

SiO2 ( 17- 25%), Al2O3 (3-8%), Fe2O3 (0.5-6%), MgO(0.1 -4%).SO3(1-3%), K2O & Na2O

(0.5-1.5%) , CaSO4 (3-5%)

To estimate the calcium content in the given solution, a known volume of cement

solution is titrated with standard EDTA solution in presence of Mg, Calcium ions present in the

cement solution can be titrated against EDTA using Patton & Reader’s indicator in the pH range

12-14. The indicator combines with Calcium ions to form a wine red coloured complex. Ca+2 +

Indicator Calcium-Indicator complex (Wine red)

Near the end point, when free calcium ions are exhausted in the solution, further addition

of EDTA, dissociates Calcium-Indicator complex, consumes the calcium ions and release free

indicator which is blue in colour. Therefore colour change is wine red to blue.

Procedure:-

Step1. Preparation of standard solution of Na2 EDTA

Weigh out the given EDTA crystals accurately into a 250 ml volumetric flask. Add quarter test

tube of ammonia. Dissolve in distilled water and dilute up to the mark, mix well.

Step 2. Determination of calcium oxide

Pipette out 25 Cm3 of the given Cement solution into a clean conical flask. Add 5ml of glycerol,

5ml of diethyl amine and and 10ml of 4N NaOH solution. Add 3-4 drops of Patton and Reeder’s

indicator. Titrate against standard EDTA solution till the colour change from wine red to clear

blue. Repeat the titration to get concordant values.

72

Step 2: Observations and calculations

S. No. Vol. of Sample

Burette readings Vol. of EDTA

Initial Final

Volume of EDTA consumed by 25 Cm3 of cement solution = -------------------

Weight of Cement in 25ml =0.1g

1000 Cm3 of 1 M EDTA = 56.08 g of CaO (Molecular mass of CaO =56.08)

-------- x -------- x 56.08

------- Cm3 of -------- M EDTA = --------------------- g of CaO

1000 x 1

= -----------------------

25 Cm3 of the Cement solution contains ------------- g of CaO

.............100

% of CaO in the given sample of cement solution = --------------------- = ---------------------

0.1

73

Result:

S.NO Sample % of CaO Signature of

the Faculty

74