1

CONTENTS

Sl.No.

Name of ExperimentsPage No.

1

Estimation of hardness of water by EDTA method5

2

Estimation of copper in brass by EDTA method11

3

Determination of Dissolved oxygen in water (Winklers method)15

4

Estimation of Chloride in Water Sample(Argentometry)19

5

Estimation of Alkalinity of Water Sample23

6

Determination of Molecular Weight and degree of poymerisation using Viscometry 29

7

Conductometric Titration of Strong Acid with Strong Base33

8

Conductometric Titration of Mixture of Acids35

9

Conductometric Precipitation Titration39

10

Estimation of Ferrous ion by Potentiometric Titration43

11

pH metry - Determination of Strength of HCl by NaOH47

12

Determination of water of crystallization of copper sulphate51

13

Estimation of Iron by Spectrophotometry53

Expt.No.1 SHORT PROCEDURE

CONTENTSTITRATION ITITRATION IITITRATION III

Standardisation of

EDTA

(EDTA Vs Std CaCl2)Determination of total hardness

(Std EDTA Vs water sample)Determination of permanent hardness

(Std EDTA Vs Boiled H2O)

Burette solution

Pipette solution

Indicator

Additional soln.

End pointEDTA solution

Std CaCl 2

EBT

Ammonia Buffer solution (5ml)

Wine red to Steel blue EDTA solution

20 ml hard water

EBT

Ammonia Buffer solution (5ml)

Wine red to steel blueEDTA solution

20ml Boiled hard water

EBT

Ammonia Buffer solution (5ml)

Wine red to Steel blue

TITRATION I

STANDARDISATION OF EDTA

Std CaCl 2 Vs EDTA Indicator: EBT

S.No.Volume of CaCl2 (ml)Burette ReadingVolume of EDTA

(ml)Concordant value

(ml)

InitialFinal

Step 1- Arriving at standard equation,

1ml of Std CaCl 2 = 1 mg of CaCO3 ( given)

V1 ml of EDTA = 20 ml of Std. CaCl 2

1 ml of EDTA = (20 / V1) ml of Std. CaCl 2

Therefore , 1 ml of EDTA = (20 / V1) mg of CaCO3 (standard equation.)

Expt.No.1 ESTIMATION OF HARDNESS OF WATER - EDTA METHODAIM

To estimate the amount of total, temporary and permanent hardness in the given sample of hard water. A standard solution of CaCl 2 is provided such that 1 ml of solution is equal to 1 mg of CaCO3 PRINCIPLE The estimation is based on the complexometric titration.

(i) Total hardness of water is estimated by titrating it against EDTA using EBT indicator.

EBT+Mn+ ([EBT-M] (complex)

EBT-M (unstable complex) +EDTA ( [EDTA-M] (stable complex) +EBT

(Wine red) (Steel blue)EBT indicator forms wine red coloured complex with hardness causing metal ions present in water. On addition of EDTA, metal ions preferably form complexes with EDTA and steel blue EBT indicator is set free. Therefore change of colour from wine red to steel blue denotes the end point.

(iii) Temporary hardness is removed by boiling the water.

Ca (HCO3)2 ( CaCO3 +CO2 (+H2O

Mg (HCO3)2 ( Mg(OH)2 +2CO2 ( The precipitate is filtered and the remaining permanent hardness is estimated using EDTA.

PROCEDURE

TITRATION I

(i) STANDARDISATION OF EDTA

Pipette out 20ml of standard CaCl2 into a 250ml conical flask. (Standard hard water is prepared by dissolving 1 g of calcium carbonate in one litre of distilled water) . Add 5ml of buffer solution and 3 drops of eriochrome black T indictor. Titrate the solution with EDTA from the burette until the colour changes from wine red to steel blue at the end point. Repeat the titration for concordant values. Let the titre value be V1ml.

TITRATION II

DETERMINATION OF TOTAL HARDNESS

Std.EDTA Vs Sample Hard Water Indicator: EBT

S.No.Volume of sample hard water (ml)Burette ReadingVolume of EDTA

(ml)Concordant value

(ml)

InitialFinal

Step 2.- Calculation of total hardness.

Volume of EDTA consumed (V2) =-------- ml

20ml of sample hard water

= V2 ml of EDTA

1000 ml of sample hard water

= V2 X (1000/20) ml of EDTA

As per standard equation,

1000ml of given hard water

= V2 X (1000/20) X (20 / V1) mg of CaCO3

= 1000 x (V2 / V1 ) mg of CaCO3

Therefore, total hardness

= ----------ppm

TITRATION II(ii) DETERMINATION OF TOTAL HARDNESS

Pipette out 20ml of sample hard water into a clean conical flask. Add 5ml of buffer solution and 4 -5 drop of eriochrome black T indicator. Titrate the wine red coloured solution with EDTA from the burette until the colour steel blue appears at the end point. Repeat the titration for concordant values. Let the titre value be V2ml.

TITRATION III(iii) DETERMINATION OF PERMANENT HARDNESS

Take 250ml of hard water sample in a 250ml beaker and boil gently for about 20 minutes. Cool, filter it into a 250ml standard flask and make the volume upto the mark. Take 20ml of this solution and proceed it in the same way as in titration (I). The volume of EDTA consumed corresponds to the permanent hardness of the water sample. Let the titre value be V3ml. Temporary hardness is calculated by subtracting permanent hardness from total hardness.

RESULT

(i) Amount of total hardness of the given sample water = ------- ppm.

(ii) Amount of permanent hardness of the given sample water = -------ppm.

(iii) Amount of temporary hardness of the given sample water = -------ppm.

TITRATION III

DETERMINATION OF PERMANENT HARDNESS:

Std. EDTA Vs Sample boiled hard water Indicator: EBT

S.No.Volume of sample boiled hard water (ml)Burette Reading Volume of EDTA

(ml)Concordant value

(ml)

InitialFinal

Step 3.- Calculation of permanent hardness.

Volume of EDTA consumed (V3) =-------- ml

20ml of boiled water

= V3 ml of EDTA

1000 ml of boiled water

= V3 X (1000/20) ml of EDTA

As per standard equation,

1000ml of given hard water

= V3 X (1000/20) X (20 / V1) mg of CaCO3

= 1000 x (V3 / V1 ) mg of CaCO3

Therefore, permanent hardness

= ----------ppm

Step 4 Calculation of temporary hardness

Temporary hardness of the given sample of water = Total hardness Permanent hardness

= ------------ppm

SHORT PROCEDURE:

CONTENTSTITRATION ITITRATION II

Standardization of Na2S2O3 (Std. K2Cr2O7 Vs Na2S2O3 ) Estimation of copper

(Std Thio Vs Alloy solution )

Burette solution

Pipette solution

Indicator

End pointNa2S2O3K2Cr2O7 Starch

Appearance of green colour

Na2S2O3Alloy solution

Starch

Appearance of green colour

TITRATION I

STANDARDIZATION OF Na2S2O3 WITH K2Cr2O7 SOLUTION

Std. K2Cr2O7 Vs Na2S2O3 Indicator : Starch

S.No.Volume of K2Cr2O7

(ml)Burette ReadingVolume of Thio

(ml)Concordant value (ml)

InitialFinal

1.

2.

3.

Volume of K2Cr2O7 (V1) = 20 ml

Strength of K2Cr2O7 ( N1 ) = N

Volume of Na2S2O3( V2 ) = ml

Strength of Na2S2O3 ( N2) = ? N

= ( 20 x N1 )/ V2 = N

Strength of Na2S2O3 is ------ N.

Expt. No 2 ESTIMATION OF COPPER IN BRASS

AIM

To estimate the amount of copper present in the given sample of brass.

PRINCIPLE

Brass is an alloy with 55% copper and 33% zinc and small amount of lead and aluminium. Brass is dissolved in con.nitric acid to convert copper present in the alloy to cupric ions. Then copper is estimated iodometrically by titrating the iodine that was liberated against standard sodium thio sulphate solution using starch as indicator.

2 Cu2+ + 4I- 2 CuI + I2

I2 + 2 Na2S2O3 Na2S4O6 + 2NaI

PROCEDURE PREPARATION OF BRASS ALLOY SOLUTION

About 0.2g of the sample of brass was weighed accurately and transferred into a clean dry 250ml beaker. To this about 10ml of con. Nitric acid was added and allowed to boil for a small interval of time till the alloy was dissolved. This was cooled, diluted with water and made upto 250 ml in a standard flask.

TITRATION I

STANDARDIZATION OF Na2S2O3 WITH K2Cr2O7 SOLUTION

20ml of the standard potassium dichromate solution is pipetted out into a conical flask. 20ml of dil.sulphuric acid and 10ml of 10% KI are added. The liberated iodine is titrated against sodium thio sulphate taken in the burette till the colour changes to yellowish green. 1ml of starch is added till the colour changes from blue to light green colour. Titration is repeated for concordancy.

TITRATION II

ESTIMATION OF COPPER

The brass solution is transferred into the 100ml standard flask and 10ml of dil sulphuric acid is added and made up to the mark using distilled water.

20ml of the alloy solution was pipetted out into a conical flask. To this aqueous ammonia is added in drops till a blue precipitate of Cu(OH)2 is formed. One or two drops of acetic acid is added to dissolve the precipitate. To this 10ml of 10% KI is added and titrated against standard thio sulphate using starch as indicator. The end point is the disappearance of blue colour and appearance of green colour.

RESULT

The given sample of brass is found contain copper to ---------%TITRATION II

ESTIMATION OF COPPER

Std. Thio Vs Alloy solution Indicator : Starch

S.No.Volume of

Alloy

Solution

(ml) Burette ReadingVolume of

Thio

(ml)Concordant value (ml)

InitialFinal

1.

2.

3.

Volume of Na2S2O3 V1 = ml

Strength of Na2S2O3 N1 = N

Volume of brass solution V2 = ml

Strength of brass solution N2 = ?

= (V1x N1)/ V2 = --------- N

Strength of copper solution is =---------N

CALCULATION OF AMOUNT OF COPPER:

Amount of Cu in 1lt of given brass solution = strength of solution x Eq. Wt of Cu

= -----N x 63.5

So, Amount of copper in 100ml of given brass solution

= (-----N x 63.5 x 100 ) / 1000

ie, ----------g of brass contains = ------g of copper

Therefore, % of copper in the given brass sample = --------g x 100

------g of brass

= %SHORT PROCEDURE

S.NoCONTENTS

TITRATION I

STANDARDIZATION OF Na2S2O3 Std. K2Cr2O7 Vs Na2S2O3TITRATION II

ESTIMATION OF D.O

Std. Na2S2O3 Vs W.Sample

1.Burette solutionNa2S2O3Std. Na2S2O3

2.Pipette solutionStd. K2Cr2O7 20ml of treated water sample*

3.Additional solution1 Test tube of 2N H2SO4 + 10ml of 10% KI-------

4.IndicatorStarchStarch

5.End pointDisappearance of blue colourDisappearance of blue colour

*200ml of sample water + 2ml of MnSO4 + 2ml of alk. KI- Shaken for 10 mins. A brown gelatinous precipitate will be formed. Dissolve it with minimum amount of Con. Sulphuric acid to get a clear reddish brown solution.TITRATION1

STANDARDISATION OF SODIUM THIO SULPHATE

Std. K2Cr2O7 Vs Na2S2O3 Indicator: Starch

S.No.Volume of K2Cr2O7 (ml)Burette Reading (ml)Volume of

Na2S2O3 (ml)Concordant value

(ml)

InitialFinal

Volume of potassium dichromate (V1) = 20 ml

Strength of potassium dichromate (N1) = N

Volume of sodium thio sulphate (V2) = ml

Strength of sodium thio sulphate (N2) = ? = V1 x N1 / V2 =--------- N

Expt.No. 3 ESTIMATION OF DISSOLVED OXYGEN IN WATER SAMPLE (WINKLERS METHOD)AIM

To determine the amount of dissolved oxygen (DO) in the given water sample by Winklers method. A standard solution of potassium dichromate of strength ______N is provided.PRINCIPLE

Two methods are widely used to determine DO are:

(a) Winklers method of iodometry

(b) Electrometric method using a membrane electrode.

Winklers methodDO reacts with Mn2+ ions in alkaline medium forming basic magnanic oxide which is a brown precipitate.

MnSO4 + 2 KOH ( Mn(OH)2 + K2SO4

2Mn(OH)2 - + O2 ( 2 MnO(OH)2 (brown precipitate)

This brown precipitate dissolves on acidification and when treated with iodide ions liberates iodine in an amount equivalent to the initial DO.

MnO(OH)2 + H2SO4 ( MnSO4 + 2H2O + [ O ] 2 KI + H2SO4 + [ O ] ( K2SO4 + H2O + I2

The liberated iodine is finally estimated by titration with sodium thio sulphate.

I2 + Na2S2O3 ( Na2S4O6 + 2 NaI

Starch + I2 ( Blue coloured complex

The stoichiometric expression relating DO and sodium thio sulphate is 1 ml of 0.0125N Na2S2O3 (( 0.1 mg DO Sodium thio sulphate (being a secondary standard) is standardized iodometrically using standard K2Cr2O7. Iodimetry : I2 (direct source) Vs Na2S2O3.

Iodometry: (oxidant + excess I- ) ( I2 (liberated) Vs S2O32-

The Net reaction is:

Cr2O72- + 14H+ + 6I- ( 2Cr3+ + 7H2O + 3I2 TITRATION II:

ESTIMATION OF DO

Std. Na2S2O3 Vs treated water sample Indicator :Starch

S.No.Volume of water sample (ml)Burette Reading (ml)Volume of

S2O32-(ml)Concordant value

(ml)

InitialFinal

1ml of 0.0125 N of S2O3 2- = 0.1mg of dissolved oxygen

____ml of ____ N of S2O3 2- = X mg of dissolved oxygen

X = (0.1 x ___ x____) / 1 x 0.0125

= _____ mg of dissolved oxygen

20 ml of water contains _____ mg of dissolved oxygen

Therefore 1000 ml of water contains = (______ x1000) / 20 mg/L = ______ mg/L

The liberated iodine in an amount equivalent to Cr2O72- reacts with sodium thio sulphate .

( In iodometric titrations, a slight excess of I2 must be added to ensure complete conversion of I- in amounts equivalent to the oxidizing agent being estimated.

( Starch is added as indicator which forms an intense blue colour weak adsorption complex with iodine present in low concentrations. The complex gets readily broken when thio sulphate addition is continued and hence a sharp colour change occurs at the end-point.

PROCEDURE

1) STANDARDISATION OF SODIUM THIO SULPHATE

20ml of std. K2Cr2O7 solution is pipetted out into a clean conical flask. About 10ml of 10% KI solution and 20ml of dil.sulphuric acid are added. The liberated iodine is titrated against sodium thio sulphate in the burette. When the solution turns yellow (pale) colour, 2 to 3 drops of freshly prepared starch indicator is added and the solution assumes intense blue colour. The addition of sodium thio sulphate is continued till the blue colour is discharged leaving behind a pale green colour (due to the presence of Cr3+ ions). The titration is repeated to get a concordant value.

2) ESTIMATION OF DO (WINKLERS METHOD)

The given water sample is filled in a reagent bottle up to rim and stoppered. This is done in order to exclude any air column present in the closed bottle that may increase the actual DO leading to an error.

With the stopper removed, manganous sulphate (36%, 2ml) and alkaline KI((10%, 2ml ) are added. In this process, some sample may overflow. The overflow may also occur when the stopper is inserted after the addition of each reagent. The stoppered bottle along with the reagents is shaken by turning it several times up and down till the formation of a brown coloured basic manganic oxide. It is subsequently dissolved by adding sulphuric acid(1:1 few drops). 20 ml of this reddish brown solution is pipetted out in to a clean conical flask and a few drops of starch solution are added. The resultant blue coloured solution is titrated against the standardised sodium thio sulphate till the end point is reached which is shown by the discharge of blue colour. The titration is performed in duplicate.

RESULT

The amount of DO present in the given water sample = --------- mg/lit.

SHORT PROCEDURE:

CONTENTSTITRATION ITITRATION II

Standardization of

Silver Nitrate

Std. NaCl Vs AgNO3 Estimation of chloride

Std. AgNO3 Vs Water Sample

Burette solution

Pipette solution

IndicatorEnd point AgNO3

Std. NaCl

1 ml of 2% K2CrO4Appearance of reddish brown colourStd. AgNO3

Water sample

1 ml of 2% K2CrO4Appearance of reddish brown colour

TITRATION I

STANDARDISATION OF AgNO3 :

Std. NaCl Vs AgNO3

Indicator: Potassium Chromate S.No.Volume of NaCl (ml)Burette Reading (ml)Volume of AgNO3 (ml)Concordant

Value (ml)

InitialFinal

Volume of sodium chloride (V1) = 20 ml

Strength of sodium chloride (N1) = N

Volume of silver nitrate (V2) = ml

Strength of silver nitrate (N2)

= ?

N2= (V1 X N1 ) / V2

=

N

Expt.No. 4 ESTIMATION OF CHLORIDE CONTENT IN WATER SAMPLE BY ARGENTOMETRIC METHOD [ MOHRS METHOD ]

AIM

To estimate the amount of chloride present in the given water sample, being supplied with standard solution of sodium chloride of strength _________N .PRINCIPLE

Generally water contains chloride ions (Cl ) in the form of NaCl, KCl,CaCl2, and MgCl2. The concentration of chloride ions more then 250 ppm is not desirable for drinking purpose. The total chloride ions can be determined by argentometric method ( Mohrs Method ).

In this method Cl ion solution is directly titrated against AgNO3 using potassium chromate ( K2CrO4) as the indicator

AgNO3 + Cl ( AgCl + NO3 ( in water ) ( white ppt )

At the end point when all the Cl ions are removed. The yellow colour of chromate changes into reddish brown due to the following reaction.

2AgNO3 + K2CrO4 (Ag2CrO4 +2KNO3 (yellow ) ( Reddish brown )

PROCEDURETitration I

Standardization of AgNO3The burette is washed well with distilled water and rinsed with small amount of AgNO3 solution. It is then filled with the same solution up to the zero mark without any air bubbles. The pipette is washed with distilled water and rinsed with the small amount of standard NaCl solution 20 ml of this solution is pipetted out in to the clean conical flask.1ml of 2% K2CrO4 indicator solution is added and titrated against AgNO3 solution taken in the burette. The end point is the change of colour from yellow to reddish brown. The titration is repeated for concordant values.

Titration IIEstimation of Chloride ion

20 ml of the given water sample is pipetted out in the clean conical flask and 1 ml of 2% K2CrO4 indicator solution is added. It is then titrated against standardized AgNO3 solution taken in the burette. The end point is the change of colour from yellow to reddish brown.

RESULT

Amount of chloride ion present in the given water sample = .ppmTITRATION II

ESTIMATION OF CHLORIDE IN WATER SAMPLE:

Std. AgNO3 Vs Water Sample

Indicator: Potassium Chromate

S.No.Volume of water sample (ml)Burette Reading (ml)Volume of AgNO3 (ml)Concordant

Value (ml)

InitialFinal

Volume water sample (V1 ) = 20 ml

Strength of water sample ( Chloride ion ) (N1) = N

Volume of silver nitrate

(V2) = ml

Strenght of silver nitrate

(N2) = N

N1 = V2 X N2

V1

=N

Calculation of amount of Chloride ion

Amount of chloride ion present in 1 litre( 1000 ml )of the water sample

=Equivalent weight of Chloride ion X strength of chloride ion ppm

= 35.46 X strength of chloride ion ppm

SHORT PROCEDURE:

CONTENTSTITRATION ITITRATION II

Standardisation of HCl

(Std NaOH Vs HCl)Estimation of alkalinity in water sample

(Std HCl Vs water sample)

Burette solution

Pipette solution

Indicator

End pointHCl

Std. NaOH

Phenolphthalein

Disappearance of pink colour

Std. HCl

Water sample

(i) Phenolphthalein

(ii) Methyl orange

(i) Disappearance of pink colour

(ii) Appearance of reddish orange colour

Strength of HCl = --------- N

The end point when phenolphthalein is used as an indicator = P

The end point when methyl orange is used as an indicator = M

Relationship in between P &MNature of alkalinityAmount of individual alkalinitiesOH-HCO3-CO32-

P = M

2P = M

P =0, M0

2P > M

2P < M

only OH-

only CO32-

only HCO3-

OH- &CO32-

HCO3&CO32-

(P or M) x 0.1 x 50

20

(2P or M) x 0.1 x 50

20

M x 0.1 x 50

20

OH- = (2P - M) x 0.1 x 50

20

CO32- = 2 (M-P) x 0.1 x 50

20

HCO3- = (M-2P) x 0.1 x 50

20

CO32- = (2P) x 0.1 x 50

20xxx

0.0

0.0

xxx

0.0 0.0

0.0

xxx

0.0

xxx0.0

xxx

0.0

xxx

xxx

Expt.No.5 DETERMINATION OF ALKALINITY IN WATER

AIMTo determine the type and amounts of alkalinity in the given water sample. A standard solution of NaOH of strength ____N is given.

PRINCIPLE

Alkalinity in water is due to the presence of soluble hydroxides, bicarbonates and carbonates. Alkalinity can be determined by

Potentiometric methods

Using pH meter

Titrimetry using different indicators

Determination of various types and amounts of alkalinity is easily carried out by titration with standard HCl employing the indicators phenolphthalein and methyl orange independently or in succession.

The following reactions occur when different types of alkalinity are neutralized with acid.

OH- + H+ ( H2O completed at pH 8.2-9.0 ----------- (1)

CO32- + H+ ( HCO3- -------------- (2)

HCO3- + H+ ( (H2CO3) ( H2O + CO2 , completed at pH 4.2-5.5---(3)

Neutralisation (1) & (2) will be notified by phenolphthalein end-point while all the three will be accounted by methyl orange end-point. Bicarbonate in eqn (3) may be due to the existence of soluble free bicarbonate salts or bicarbonates resulting from half neutralization of soluble carbonates (eqn. (2))

Various steps to be followed:

a) A known volume of water sample is titrated against std. HCl using first phenolphthalein indicator till end-point (P) and the titration is continued without break using methyl orange indicator till the equivalence end-point (M).

TITRATION : 1

STANDARDISATION OF HCl :

Std. NaOH Vs HCl Indicator: Phenolphthalein

S.No.Volume of NaOH (ml)Burette ReadingVolume of HCl

(ml)Concordant value

(ml)

InitialFinal

Volume of sodium hydroxide (V1) = 20 ml

Strength of sodium hydroxide (N1) = N

Volume of HCl (V2) = ml

Strength of HCl (N2) = V1 X N1 / V2TITRATION II

ESTIMATION OF ALKALINITY IN WATER SAMPLE

Std.HCl Vs Water sample

Indicator:1. Phenolphthalein

2. Methyl orange

S.No.Volume of water sample

(ml) Burette Reading Volume of HCl

(ml)Concordant value

(ml)

InitialFinal

1

2PMPMPMPM

b) From the magnitudes of the P & M, the nature of alkalinity can be arrived as follows:

(i) P = M => Presence of only OH-(ii) 2P = M => Presence of only CO32-(iii) P =0, M#0 => Presence of only HCO3-

(iv) 2P > M => Presence of OH- & CO32-

(v) 2P < M => Presence of HCO3- & CO32-

(Mixture of OH- & HCO3-are not listed since they do not exist together and are considered equivalent to CO32-).

PROCEDURE

TITRATION I

STANDARDISATION OF HCl

Exactly 20 ml of the given standard NaOH solution is pipetted out into a clean conical flask and 2 drops of phenolphthalein indicator is added. The solution is titrated against the given HCl taken in the burette. The pink colour of the solution in the conical flask disappears at the end-point. The titre value is noted down from the burette and the titration is repeated to get concordant value.

TITRATION II

ESTIMATION OF ALKALINITY IN WATER SAMPLE Exactly 20 ml of water sample is pipetted out into a clean conical flask. Few drops of phenolphthalein indicator are added and titrated against the standardized HCl taken in the burette. The end-point is the disappearance of pink colour, which is noted as P. Into the same solution few drops of methyl orange indicator is added. The solution changes to yellow. The titration is continued further by adding same HCl without break till the end-point is reached. The end point is the colour change from yellow to reddish orange. The titre value is noted as M.

The experiment is repeated to get concordant values. From the magnitudes of P & M values, the type of alkalinity present in the water sample is inferred and the individual amounts are calculated and reported.

RESULT

1) The type of alkalinity present in the water sample = ------ions.

2) The individual amounts of alkalinity present in the water sample

= ----- ppm

(i) Amount of OH- in water sample:

Volume of HCl (V1) = (2P-M) = ml

Strength of HCl (N1) = N

Volume of water sample (V2) = 20ml

Strength of OH- inwater sample (N2) = V1 X N1 / V2

Amount of OH-in water sample = N2 X 50 g/lit ( 50 is the eq.wt of CaCO3)

= N2 X 50 X1000 mg/lit. = -------------- ppm.

(ii) Amount of CO32- in water sample:

Volume of HCl (V1) = 2(M-P) = ml

Strength of HCl (N1) = N

Volume of water sample (V2) = 20 ml

Strength of CO32- in water sample (N2) = V1 X N1 / V2

Amount of CO32- inwater sample = N2 X 50 g/lit

= N2 X 50 X1000 mg/lit. =-----------ppm.

Solvent used

= Water

K of the polymer solvent system

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

a of the polymer-solvent system

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

volume of liquid taken for finding the flow time = 10 mlflow time of the solvent

( t0 )

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

s.noConc.

g/dl (%)Flow time (t)sec(r = t / t0

ln (rln (r / C(sp=(r -1(sp / C

S.No.PolymerSolventK(10-5(g/ml)

a

1.

2.

3.

4. Polyvinyl alcohol

Polyvinyl pyrrolidone

Polystyrene (atactic)

Polystyrene (isotactic)Water

Water

Benzene

Benzene

45.3

39.3

11.5

10.6 0.64

0.59

0.73

0.735

Expt.No. 6 DETERMINATION OF MOLECULAR WEIGHT AND

DEGREE OF POLYMERISATION OF A POLYMER ( VISCOSITY AVERAGE METHOD) AIM

To determine the molecular weight and degree of polymerization of a polymer by viscosity average method. PRINCIPLE Viscosity average method is based on the flow behaviour of the polymer solutions . According to Mark Hawnik equation, the intrinsic viscosity of a polymer is given as

[(]int = KMaWhere,

M = molecular weight of the polymer

K & a are constants for a particular polymer solvent system

( = Intrinsic viscosity = [(sp/C]C=0 = [(r/C]C=0

(sp = specific viscosity = (r 1

(r = relative viscosity = (/(0 = t / t0Since accurate measurement of absolute viscosity is a difficult task, relative viscosity is taken into account.

( = Viscosity of the polymer solution(0 = Viscosity of the pure solvent

t = flow time of the polymer solution

t0 = flow time of the pure solvent

The flow time of the polymer solution (t) and that of the pure solvent (t0) are found experimentally and substituted to get (sp , (r and thus [(]int.

Knowing K & a, molecular weight of the polymer solution is calculated.DP = M / m (M= mol.wt of polymer, m = mol. wt of monomer)PROCEDURE

Accurately 1g of polyvinyl pyrrolidone is weighed, dissolved in water and made up to 100ml (1dl) in a standard flask.From the bulk solution, polymer solutions of conc. 0.1g/dl, 0.2g/dl, 0.3g/dl.0.4g/dl and 0.5g/dl are prepared using the relation V1N1 = V2N2[E.g. X * 1g / dl = 0.2g / dl * 100ml,

Where X = volume of bulk solution to be taken for preparing 100ml of 0.2g/dl Polymer solution]

A well cleaned Ostwald viscometer is rinsed with water and filled with 10ml of distilled water, Water in the viscometer is sucked into the upper bulb using a rubber bulb. The time taken for water to flow from the upper mark to the lower mark is measured with a stop clock and noted as t0.

Water from the viscometer is drained completely and 10ml of the polymer solution of conc. 0.1g/dl is poured in the viscometer. The flow time of the polymer solution is found and noted as t. The procedure is repeated with the other solutions of the polymer.

From the values of t and t0 , (r / C and (sp / C are calculated and graphs with (sp / C Vs C and ln (r / C Vs C are drawn. The straight lines obtained are extrapolated to zero concentration. The intercept values are equal to [(]int. From [(]int molecular weight of the polymer (M) is calculated using the formula [(]int = KMa and the table.From the values of M and m , degree of polymerization can be calculated.RESULT:

The molecular weight of the given polymer = The degree of polymerization of the polymer =

Rough titration:

S.No.Volume of NaOH

added (ml)Observed conductance

(m mho)

Fair titration:

S.No.Volume of NaOH

added (ml)Observed conductance

(m mho)

Volume of Sodium Hydroxide (V1) = ml (from fair graph)

Normality of Sodium Hydroxide (N1) = N

Volume of Strong acid (V2) = ml

Normality of Strong acid (N2) = (V1 x N1) /V2

= --------------- NThe strength of the given strong acid is found to be = --------N Expt. No.7 CONDUCTOMETRIC TITRATION OF STRONG ACID

WITH STRONG BASE

AIM

To determine the strength of a given strong acid conductometrically. A standard solution of NaOH of strength ---------N is provided.

PRINCIPLE

Solution of electrolytes conducts electricity due to the presence of ions. The specific conductance of a solution is proportional to the concentration of ions in it. The reaction between HCl and NaOH may be represented as,

HCl +NaOH -( NaCl + H2O

When a solution of hydrochloric acid is titrated with NaOH, the fast moving hydrogen ions are progressively replaced by slow moving sodium ions. As a result conductance of the solution decreases, this decrease in conductance will take place until the end point is reached. Further addition of alkali raises the conductance sharply, as there is an excess of hydroxide ions.

A graph is drawn between volume of NaOH added and the conductance of solution. The exact end point is intersection of the two lines.

PROCEDURE

The given HCl is made up in a 100ml standard flask. 20 ml of this solution is pipetted out in a beaker and diluted to 50ml using distilled water. The burette is filled with standard sodium hydroxide upto the mark.

A conductivity cell is dipped into the beaker with HCl solution and connected to the terminals of the conductivity bridge. About 1ml of Std NaOH is added and stirred well for 30 seconds. The conductance is measured and the titration is continued till five measurements after the endpoint. A graph is plotted for the conductance values against the volume of NaOH and the endpoint range is fixed.

The above titration is repeated again and the exact endpoint is found out by adding in increments of 0.1ml of NaOH in the end point range and continued after endpoint upto five readings.

A graph is plotted with the conductance values against the volume of NaOH and then the strength of the strong acid is found out.

RESULT

The strength of the given strong acid is found to be ---------------N

Rough titration:

S.No.Volume of NaOH

added (ml)Observed conductance

(m mho)

Fair titration:

S.No.Volume of NaOH

added (ml)Observed conductance

(m mho)

(i) Calculation of strength of HCl:

Volume of NaOH (V1) = ml (from fair graph)

Strength of NaOH (N1) = N

Volume of HCl (V2) = ml

Strength of HCl (N2) = (V1 x N1 ) / V2

Strength of HCl = ---------- N

Expt. No 8 CONDUCTOMETRIC TITRATION OF MIXTURE OF ACIDS

AIM

To determine the strength of strong acid and weak acid present in the given acid mixture

PRINCIPLE

Solution of electrolytes conducts electricity due to the presence of ions. Since specific conductance of a solution is proportional to the concentration of ions in it, conductance of the solution is measured during the titration.

HCl + NaOH ( NaCl + H2O (I neutralization)

CH3COOH + NaOH ( CH3COONa + H2O (II neutralization)

When a solution of HCl is treated with NaOH the fast moving hydrogen ions are progressively replaced by slow moving sodium ions. As a result conductance of the solution decreases. This decrease will take place until the first neutalisation point is reached. Further addition of alkali results in formation of sodium acetate. Since sodium acetate is stronger electrolyte than acetic acid, conductivity slowly increases until all acetic acid is completely neutralized.(II Neutalisation) This is due to the presence of fast moving OH- ions. Anymore addition of alkali increases the conductance sharply.

PROCEDURE

The burette is filled with NaOH solution upto zero mark. The given unknown solution (mixture of a weak & a strong acid) is transferred into a 100ml standard flask and made upto the mark with distilled water. 20ml of the made up solution is pipetted out into a clean 100ml beaker. The solution is diluted to 50ml using distilled water. A conductivity cell is dipped into the solution and the terminals are connected to a conductivity meter.

The burette solution is added to the unknown solution in the beaker in 1 ml increments, the solution is stirred using a glass rod, and the observed conductance values are read from the meter. The conductance values show decrease in the initial values, then gradually increases and finally shows a steep increase. The titration hence shows two end-points (ie) I neutralization (strong acid) & II neutralization (weak acid).

The titration is repeated with the same procedure by adding 0.1 ml increments of the burette solution in the region of the end-point and the conductance values are noted for all the increments. The accurate end-point is obtained by plotting a graph between observed conductance Vs volume of NaOH added.

RESULTThe strength of acids present in the given unknown solution are a) Strong acid = N b) Weak acid = N

(ii) Calculation of strength of CH3COOH:

Volume of NaOH (V1) = ml (from fair graph)

Strength of NaOH (N1) = N

Volume of CH3COOH (V2) = ml

Strength of CH3COOH (N2) = (V1 x N1 ) / V2

Strength of CH3COOH = ---------- N

Rough titration:

S.No.Volume of Na2SO4 (ml)Conductance in mmho.

Fair titration:

S.No.Volume of Na2SO4(ml)Conductance in

mmho.

Expt.No9 CONDUCTOMETRIC PRECIPITATION TITRATION

AIM

To determine the amount of BaCl2 present in the given solution by conductometric precipitation titration.

PRINCIPLE

Solution of electrolytes conduct electricity due to the presence of ions. Since specific conductance of a solution is proportional to the concentrations of ions in it, conductance of solution is measured during titration.

In the precipitation titration, the ions are converted into insoluble precipitate, which will not contribute to the conductance.

When Na2SO4 is added slowly from the burette to the solution of barium chloride, barium sulphate gets precipitated while chloride ions are remain as soluble ions with sodium ions. . { Ba2+ + 2 Cl- } + {2Na+ + SO42-} ( BaSO4 ( + 2Na+ + 2Cl-

After the end-point, when all the Ba2+ ions are replaced, further addition of Na2SO4 increases the conductance. This is due to the presence of excess of Na+ and SO42- ions in the solution.

PROCEDURE

The burette is filled with Na2SO4 solution upto the zero mark. The given unknown solution is carefully transferred into a 100ml standard flask using a funnel and glass rod and the solution is made upto the mark using distilled water. 20ml of the made up solution is pipeted out into a clean 100ml beaker. The conductivity cell is placed in it and then the solution is diluted to 50ml by adding distilled water. The conductivity cell is connected to conductivity meter.

1ml of the burette solution is added to the solution taken in the beaker, stirred and the conductance is read from the conductivity meter. With successive additions of sodium sulphate solution from the burette, the conductance values decrease first and then start increasing which is the end point of the titration. After reaching the end point the titration is continued for few more readings.

The titration is repeated with the same procedure. In the range of the end point the titration is carried out by adding 0.1ml increments and the accurate end point is obtained by plotting a graph between the observed conductance values and the volume of sodium sulphate solution added.

RESULT

The amount of BaCl2 present in 1 litre of the solution is -------g.

Calculation of strength of BaCl2:

Volume of Na2SO4 (V1) = ml (from fair graph)

Strength of Na2SO4 (N1) = N

Volume of BaCl2 (V2) = ml

Strength of BaCl2 (N2) = (V1 x N1 ) / V2Strength of BaCl2 = ---------- N

Amount of BaCl2 present in

1 litre of the solution = Strength x equivalent weight of BaCl2(112.14) = ---------- g

Rough titration:S.No.Volume of dichromate (ml)EMF (milli volt)

Fair titration:

S.NoVolume of Dichromatein mlEmf in mVoltE in mVoltV in mlE/V in m Volt/ml

Expt. No 10 ESTIMATION OF FERROUS ION BY POTENTIOMETRIC TITRATION.

AIM

To estimate the amount of ferrous ion present in the given solution potentiometrically. A standard solution of potassium dichromate of strength ---------- N is provided.

PRINCIPLE

Potentiometric titrations depend on measurement of emf between reference electrode and an indicator electrode. When a solution of ferrous iron is titrated with a solution of potassium dichromate, the following redox reaction takes place.

6Fe2+ + Cr2O72- + 14 H+ ( 6Fe3+ + 2Cr3+ + 7H2O

During this titration Fe2+ is oxidised in to Fe3+, whose concentration increases. At the end point, there will be a sharp change in the emf values called sweeping potential due to sudden removal of all Fe2+ ions.

The cell is set up by connecting this redox electrode with a calomel electrode as shown below:

Pt, Fe2+, Fe3+// KCl , HgCl2 (s), Hg

A graph between emf measured against the volume of potassium dichromate added is drawn and the end point is noted from the graph.

PROCEDURE

The given Ferrous solution is made up in a 100ml standard flask. Std. Potassium dichromate solution is filled in the burette upto the mark.

20ml of Ferrous solution is pipetted out into a 100 ml beaker. 10ml of dil.H2SO4 and 20ml of distilled water are added. A platinum electrode and a calomel electrode are dipped into this solution and connected to a potentiometer. Then 1ml of potassium dichromate is added to the solution and stirred well for 30 seconds. The emf is measured and the titration is continued by adding potassium dichromate in 1ml increments till five measurements after the end point.

A graph is drawn by plotting the emf against the volume of potassium dichromate and the end point range is fixed.

About 20ml of Ferrous solution is pipetted out and the titration is continued by adding 0.1ml increments of potassium dichromate in the end point range. The emf is measured for each 0.1ml after stirring the solution well.

A graph is plotted between emf and the volume of potassium dichromate and also a first derivative graph is plotted (E/V against vol. of K2Cr2O7). The strength of Ferrous solution and the amount of Ferrous ion present are calculated from the end point.

RESULT

The amount of Ferrous ion present in the given solution is = ------------ g

Rough titration:

ROUGH GRAPH

EMF(mV)

Volume of Potassiumdichromate

FAIR GRAPH

E/V

Volume of Potassiumdichromate

Volume of Potassim dichromate (V1) = ml (from fair graph)

Normality of Potassium dichromate (N1) = N

Volume of Ferrous sulphate (V2) = ml

Normality of Ferrous sulphate (N2) = (V1 x N1 ) / V2

= ------------ N

Amount of Ferrous ion present

in 1000ml of the solution = Sterngth x equivalent weight of Fe (55.85)

= g

Rough titration:

Std. NaOH Vs HCl.

Volume of NaOH (ml) pH

ROUGH GRAPHFAIR GRAPH

pH

pH/V

Eq.Pt

Volume of NaOH(ml)Volume of NaOH(ml)

Expt.No. 11 DETERMINATION OF STRENGTH OF HCl WITH NaOH

BY pH METRYAIM

To determine the strength of given HCl by pH metry. A standard solution of ______ N NaOH is provided.

PRINCIPLE

The pH of a solution is related to H+ ions concentration by the following formula.

.pH = -log 10 [ H+ ]

pH of a solution is indirectly related to H+ ion concentration. When NaOH is added slowly to HCl, H+ ions get neutralized by OH- ions. The pH increases slowly.

H+ + Cl- + Na+ + OH- ( Na+ + Cl- + H2O

When all H+ ions of HCl are neutralized at the end point, addition of NaOH causes high increase in pH because of the addition of excess OH- ions.

PROCEDURE

The burette is washed with distilled water, rinsed with the given std. Sodium hydroxide and filled with the same solution. Exactly 20ml of the given HCl solution is pipetted out into a clean beaker. It is then diluted to 50ml with distilled water. A glass electrode is dipped into the solution and it is connected to a pH meter.

Now NaOH is gradually added from the burette to HCl taken in the beaker. pH of the solution is noted for each addition of NaOH. This process is continued until atleast 5 readings are taken after the end point.

A fair titration is performed to find the exact end point.

RESULT

(i) Strength of the given HCl solution = ---------- N

Fair titration:

Std.NaOH Vs HCl

S.NoVolume of NaOH (ml)pHpHVpH/V

Volume of NaOH (V1) = ml (from fair graph)

Strength of NaOH (N1) = N

Volume of HCl (V2) = ml

Strength of HCl (N2) = (V1 x N1 ) / V2

Strength of HCl = ---------- N

Calculation:

Wt of empty crucible with lid = W1 g

Wt of crucible with lid+ Crystalline Copper sulphate = W2 g

Wt of Crucible with lid and anhydrous Copper sulphate = W3 g

Wt of crystalline Copper sulphate

= (W2 _ W1) g

Wt of anhydrous Copper sulphate

= (W3 W1) g

Therefore, Wt of water

= ( W2 W3) g

(W2 W1) g hydrated salt contains (W2 W3) g of water.

Therefore, 100g hydrated salt contains = (W2 W3) x 100 ( W2 W1) Percentage of water of crystallization = --------------------Expt. No:12 DETERMINATION OF WATER OF CRYSTALLISATION OF A CRYSTALLINE SALT (COPPER SULPHATE)

AIM:

Determine the percentage of water of crystallization in crystalline Copper sulphate.

PRINCIPLE:

When hydrated Copper sulphate is heated, it loses its water of crystallization and a residue of anhydrous Copper sulphate is left behind.

CuSO4 .5H2O ( CuSO4 + 5H2O

A known weight of AR Copper sulphate crystals are heated and the weight of anhydrous Copper sulphate is determined. From the weight loss, the percentage of water is calculated.

PROCEDURE:

A silica crucible is heated to dull redness over a clay pipe triangle for about 15 minutes using a non luminous flame .Then it is heated strongly. After heating the crucible is kept in a dessicator, allowed to cool for about half an hour and weighed accurately.(W1 g)

About one gram of crystalline AR Copper sulphate is introduced in the crucible and is again weighed accurately. (W2 g). It is then heated strongly keeping the lid slightly tilted to one side for the water vapour to escape. Heating is continued for half an hour. The crucible and contents are then cooled in a desiccator and weighed. (W3 g) . The process is repeated for concordance. A duplicate is also conducted.

RESULT:

The percentage of water of crystallization in hydrated Copper sulphate = -------

S.No.Concentration (N) Absorbance

Amount of Iron = Strength X Eq. Wt (55.85) MODEL GRAPH

ABSORBANCE

CONCENTRATION

Expt.No13 ESTIMATION OF IRON BY SPECTROPHOTOMETERY

AIM

To estimate the amount of Fe3+ ions present in the given water sample using spectrophotometer.

PRINCIPLE

When a monochromatic light passes through a homogeneous coloured solution, a portion of incident light is reflected, a portion is absorbed and the remaining is transmitted.

Io = Ir + Ia + It

Where

Io = intensity of light entering solution

Ir = intensity of incident light reflected

Ia = intensity of light absorbed

It = intensity of light transmitted

Ir is usually eliminated and hence Io = It + Ia . The mathematical statement of Lambert Beers law is given by

T = I / Io = 10 -(CIWhere T = transmittance of solution

Io = intensity of light entering of solution (incident light)

I = intensity of light leaving solution (transmitted light)

( = molar absorption co-efficient

C = Concentration of the solution in moles/lit

l = Path length of light through the solution.(cm)

(or) A = log Io / I = (Cl

Where A is the absorbance, or optical density of solution.

i.e., when a ray of monochromatic light passes through an absorbing medium, its intensity decreases exponentially, as the concentration of the absorbing substance and the path length increases independently. Keeping the path length constant, (say l=1 cm) , the variation is with reference to only concentration, C.

Fe3+ ion does not give any colour in solution. However, it develops a red colour when it reacts with KCNS solution.

Fe3+ + 6KCNS ( [Fe (CNS) ]3- + 6K+

Red coloured complex

Further, this colour is in the blue region, (( = 480 nm). Spectrophotometer has a wide range of adaptability that allows selection of monochromatic light of any wavelength in the visible spectrum.LAYOUT OF SPECTROPHOTOMETER

I0

ELECTRICAL

SLIT

SIGNAL SOURCE MONOCHROMATOR SAMPLE CELL DETECTORDISPLAYINSTRUMENTATION

The light source is an ordinary bulb and monochromatic light is obtained by using either a glass prism or a diffraction grating. The monochromatic light is then passed through the filter and is directed through a cell containing the sample. The light that penetrates hits photoelectric cell and the output of this can be seen in the display.

PROCEDURE

Switch on spectrophotometer and warm up to about 10 minutes. Adjust the monochromator for ( = 480nm. The blank sample is a portion of distilled water used for the preparation for various concentration of Fe3+ thiocyanate solution. Keep the blank sample (distilled water) in the cell and adjust the instrument to yield a light transmission percentage corresponding to 100 for which absorbance is zero. Similarly keep the various unknown concentrations of the iron solution in the cell one by one and measure the corresponding absorbance. Also measure the absorbance of the given solution. Draw the calibration graph to determine the concentration of the given solution.

RESULT

The strength of iron present in the given solution = ----N The amount of iron present in the given solution = ----------- ppm

CHEMISTRY PRACTICALS -- VIVA-VOCE QUESTION BANK

1.ESTIMATION OF HARDNESS1. What is Hardness?2. What are the two types of hardness.3. Write the structure of EDTA.4. Give the reaction between EBT and metal ions.5. What is the pH range for a complex stability.6. What is the buffer used here?7. Give the reason for formation of red and blue colour .8. What are the ill effects of hardness.9. What may be the range of hardness in a portable water sample.10. What is the need of filtration during the experiment?11. What are the units by which hardness is expressed?12. What is the other name for Eriochrome black T?2.ESTIMATION OF ALKALINITY1. What is alkalinity?2. What are the ions responsible for alkalinity?3. What are the five possible alkalinities?4. What are the indicators used ?5. What is equivalent. weight of CaCO3.6. Why we are taking CaCO3 equivalence as reference?7. What is the reaction of Phenolphthalein end point?8. What is PPM?9. Explain Lewis concept.10. Expalin Bronsted Lowry concept .11. What is the colour of phenolphthalein in acidic and basic mediums?12. What is the colour of methyl orange in acidic and basic mediums?3.ESTIMATION OF DISSOLVED OXYGEN

1. What is the extent of oxygen dissolution in water at 30C?2. What is the need of determining the amount of DO?3. What is Winklers reagent?

4. What are the reactions involved in DO estimation?5. Why are we dissolving the precipitate in sulphuric acid?6. What is the principle of iodometry and iodimetry?7. What is the name of brown precipitate we are getting?8. How can we avoid dissolution of O2 in water?9. Why should we put stopper always on the bottle?10. Explain the process of Winklers method?4.ESTIMATION OF CHLORIDE:

1. Explain the principle behind the argentometry?2. What do you mean by back titration?3. Why are we taking excess (40ml) of Silver nitrate?4. Why are we getting a blurred solution during the titration?5. What is the reaction between alum and burette solution ( thio cyanate)?6. What type of medium do you prefer for chloride estimation?7. What is the colour change that infers you regarding the end point?8. What is break point chlorination?9. What is the relationship between ppm and gm/ml?10. What are the different sources of chlorine in water?5.DETERMINATION OF MOLECULAR WEIGHT OF POLYMER (VISCOSITY AVERAGE METHOD)

1. What is a polymer?

2. What is viscosity average method?

3. Give Mark Howink equation

4. What are the factors influencing constant a?

5. Give the unit of viscosity.

6. What is relative viscosity?

7. Define Specific viscosity.

8. What is the name of viscometer used in this experiment?

9.. Give the equation relating flow time with viscosity.

10. Draw the structure of polyvinyl pyrrolidone

11. What type of graph will be obtained when you plot (sp Vs C and ln (r /C Vs C?

12. Give the value of k and a for polyvinyl pyrrolidone water system.

6,7,8.CONDUCTOMETRIC TITRATIONS (ACID-BASE, MIXTURE OF ACIDS & PRECIPITATION)

1. Define the term conductivity?

2. Give the unit of conductance.

3. What is specific conductance?4. Define Equivalent conductance and molar conductance

5. Explain why we get V shaped graph for conductometric titration of HCl Vs NaOH?

6. List out the advantages of conductometric titrations

7. Draw the rough graph obtained by plotting conductance Vs Vol of NaOH in the estimation of mixture of acids

8. Which acid will be neutralised first when the mixture of HCl and acetic acid is titrated against NaOH?

9. Why the conductance decreases until the first neutralization point is reached?

10. Explain why after the first neutralization point conductance increases slowly then shows steep rise.

11. Explain the graph obtained by plotting volume of Na2SO4 against conductance in precipitation titration.

9. pH metry1. Define pH

2. Give the principle of pH metry

3. Name the electrodes used in the determination of pH of a solution.

4. Which electrode acts as anode and which acts as cathode?

5. What is the effect of temperature on pH

6. What is the effect of dilution on pH of an acidic solution?

7. What is the pOH of pure water at 25C

8. What is a combined electrode?

9. What is the significance of pH titration?

10. Brief the function of calomel electrode.

11. What is the pH of lime juice, blood and de-ionised water?

10.POTENTIOMETRY REDOX TITRATION1. What is an electrochemical cell?

2. What is Single electrode Potential?

3. What is Standard electrode potential?

4. Define reduction potential

5. Mention the factors affecting electrode potential?

6. Give the formula to calculate EMF of a cell

7. Name the electrodes acting as cathode and anode in this experiment

8. When ferrous sulphate is titrated with potassium dichromate which element will

undergo oxidation and which will undergo reduction?

9. What is redox titration?

10. Give the redox reaction taking place when FeSO4 is titrated against K2Cr2O711. In the reaction between FeSO4 against K2Cr2O7 , why Fe is said to be oxidized and Cr

is said to be reduced?

12. How will you construct galvanic cell for measuring EMF of FeSO4 Vs K2Cr2O7 ?

13. Why Platinum electrode is called as oxidation reduction electrode in the presence of

Fe2+ and Fe3+ ?

14. What is the reduction electrode potential of calomel electrode?

15. Give the advantages of Potentiometric titrations.

11.ESTIMATION OF IRON BY SPECTROPHOTOMETERY

1. What is the principle of spectrophotometry?

2. How the light from monochromatic source is distributed on falling upon medium?

3. What is absorbance.

4. What is transmittance

5. What is a spectrophotometer and spectrophotometry?

6. State Beer-Lamberts law

7. What is the role of KCNS in the estimation of iron by spectrophotometry?

8. Why the monochromator is adjusted for ( = 480nm during the estimation of iron?

9. Mention the working range of wave length of spectrophotometry.12.WATER OF CRYSTALLISATION1. What is the molecular formula for hydrated copper sulphate?

2. Give the reaction for the dehydration of copper sulphate?

3. What is the colour change for dehydration of copper sulphate?

4. What is the molecular weight of hydrated copper sulphate?

5. What is gravimetry?

6. What are the precautions to be taken during gravimetric analysis?

13. COPPER IN BRASS BY EDTA METHOD1. What are alloys?

2. What are the purpose of alloying?3. What is the compostion of brass?4. What is EDTA?5. What is EBT ? What is the role of indicator in this estimation?6. What are the types of alloy?7. Write the structure of EDTA?8. Do you add any additional solution during the reaction? If so, why?9. Give the principle behind estimation of copper in brass by EDTA method?10. Why should we dissolve the brass in con. Nitric acid?

_1246877897.xlsChart12

5

10

15

20

25

30

Concentration (g/dl)

nsp/C

Graph - I

Sheet1

112

210

38

46

54

66

78

810

912

1014

1366

2384

3398

4412

5422

6434

7445

8456

9470

10495

11760

12798

13805

14813

15818

016

110

28

311

48

58

66

712

87

950

1010

115

127

134

146

154

034

130

227

323

419

517

618

719

820

921

1022

1126

1230

1334

1438

1542

015

115

215

315

415

515

616

718

820

922

1024

0

15

210

315

420

525

05

110

215

320

425

530

030

125

220

315

410

55

Sheet1

0

0

0

0

0

0

0

0

0

0

Volume of NaOH

Conductance

Hcl Vs std. NaOH

Sheet2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Vol. of potassium dichromate

EMF

EMF Vs std.potassium dichromate

Sheet3

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

Volume of potassium dichromate

emf (mV)

emf Vs std. potassoim dichromate

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Vol. of dichromate

E/V (ml)

Differential Graph

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Vol. of potassium dichromate

E/V (ml)

Differential Graph

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

Volume of NaOH

pH

pH-Metry - Rough

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Volume of NaOH

pH/V

pH - Metry-Fair

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Volume of NaOH

Conductance

Mixture of Acids

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

Volume of Sodium Sulphate

Conductance

precipitation

0

0

0

0

0

0

Concentration (M)

Absorbance

Spectrophotometry

0

0

0

0

0

0

Concentration (ppm)

Intensity of Emitted Light

Flame Photometry

0

0

0

0

0

0

Concentration (g/dl)

nsp/C

Graph - I

0

0

0

0

0

0

Concentration (g/dl)

nr/C

Graph - II

_1261298455.xlsChart13

30

25

20

15

10

5

Concentration (g/dl)

lnnr/C

Graph - II

Sheet1

112

210

38

46

54

66

78

810

912

1014

1366

2384

3398

4412

5422

6434

7445

8456

9470

10495

11760

12798

13805

14813

15818

016

110

28

311

48

58

66

712

87

950

1010

115

127

134

146

154

034

130

227

323

419

517

618

719

820

921

1022

1126

1230

1334

1438

1542

015

115

215

315

415

515

616

718

820

922

1024

0

15

210

315

420

525

05

110

215

320

425

530

030

125

220

315

410

55

Sheet1

0

0

0

0

0

0

0

0

0

0

Volume of NaOH

Conductance

Hcl Vs std. NaOH

Sheet2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Vol. of potassium dichromate

EMF

EMF Vs std.potassium dichromate

Sheet3

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

Volume of potassium dichromate

emf (mV)

emf Vs std. potassoim dichromate

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Vol. of dichromate

E/V (ml)

Differential Graph

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Vol. of potassium dichromate

E/V (ml)

Differential Graph

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

Volume of NaOH

pH

pH-Metry - Rough

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Volume of NaOH

pH/V

pH - Metry-Fair

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Volume of NaOH

Conductance

Mixture of Acids

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

0

0

0

0

0

0

0

0

0

0

0

Volume of Sodium Sulphate

Conductance

precipitation

0

0

0

0

0

0

Concentration (M)

Absorbance

Spectrophotometry

0

0

0

0

0

0

Concentration (ppm)

Intensity of Emitted Light

Flame Photometry

0

0

0

0

0

0

Concentration (g/dl)

nsp/C

Graph - I

0

0

0

0

0

0

Concentration (g/dl)

nr/C

Graph - II