Vi Semester Manual -1

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VI SEMESTER B.Sc. “GOVERNMENT COLLEGE FOR WOMEN, KOLAR” . INORGANIC -VII

1

Part-I: Preparation of standard ferrous ammonium sulphate (Mohr’s salt) solution: -

Observation:

1) Mass of weighing bottle + FAS crystals (

2) Mass of weighing bottle after transferring crystals (

3) Mass of FAS crystals transferred ( (

4) Gram equivalent mass of FAS (

Calculation: Normality of FAS solution

Part- II: Standardization of potassium dichromate solution:-

Observation:

1) Burette : K 2Cr 2O7 solution2) Conical flask : 25 cm 3 FAS + 10 cm 3 acid mixture

3) Indictor : Diphenylamine

4) End point : Dark green to bluish-violet

Tabular column:

Trial No.

Burette Readings

I II III

Final Burette Reading

Initial Burette Reading

Volume of K 2Cr 2O7 run down in cm 3

Concordant burette reading ( VK2Cr 2O 7 = ...........cm3 )

Calculation:( N x V ) K2Cr 2O 7

= ( N x V ) FAS

N K2Cr 2O 7=

( N x V ) FAS _____________

VK2Cr 2O 7

=

= ............ N Normality of potassium dichromate solution = -------------N




2

Experiment No. 1Estimation of percentage of iron in haematite using diphenylamine as an internal

indicator.Aim: To estimate the percentage of iron present in given haematite ore using standard K 2Cr 2O7 solution and diphenylamine as an internal indicator.

Theory: i) Potassium dichromate solution is standardized using standard ferrous ammoniumsulphate and diphenyl amine as indicator. To get a sharp end point titration is carried out in

presence of sulphuric acid – phosphoric acid mixture.

K2Cr 2O 7 + 4H 2SO 4 K2SO 4 + Cr 2(SO 4)3 + 4H 2O +3(O)

[ 2FeSO 4(NH 4)2SO 4 6H 2O + H 2SO 4 + (O) Fe 2(SO 4)3 + 2(NH 4)2SO 4 6H 2O + H 2O ] x 3

K2Cr 2O 7 + 7H 2SO 4 +6FeSO 4(NH 4)2 SO 4 6H 2O 3Fe 2(SO 4)3 + 6(NH 4)2SO 46H 2O + K 2SO 4 + Cr 2(SO 4)3 +7H 2O

ii) Haematite ore is mainly contains ferric oxide, Fe 2O3. A known weight of haematite isdissolved in 1:1 HCl. The insoluble impurities are filtered off. The filtrate which contains Fe 3+ isreduced to Fe 2+ by stannous chloride and resulting Fe 2+ is titrated against potassium dichromatesolution using diphenylamine indicator.

Fe 2O 3 + 6HCl 2FeCl 3 + 3H 2O

2FeCl 3 + SnCl 2 2FeCl 2 + SnCl 4SnCl 2 + 2HgCl 2 Hg 2Cl 2 + SnCl 4

K2Cr 2O 7 +14HCl + 6FeCl 2 2KCl + 2CrCl 3 + 6 FeCl 3 + 7H 2O

Procedure: Part-I: Preparation of standard ferrous ammonium sulphate (Mohr’s salt)solution:- Weigh accurately (9.8 g) the given ferrous ammonium sulphate (Mohr’s salt) crystalsand transfer into a 250 cm 3 standard flask. Add few drops of concentrated H 2SO 4 and dissolve indistilled water and make up the solution upto the mark and shake well for uniform concentration.Calculate the normality of the ferrous ammonium sulphate solution prepared.

Part- II: Standardization of potassium dichromate solution:- Pipette out 25 cm 3 of the prepared ferrous ammonium sulphate solution into a clean 250 cm 3 conical flask. Add 10 cm 3 ofacid mixture (H 2SO 4 and phosphoric acid) and 4-5 drops of diphenyl amine indicator. Titrate thissolution against potassium dichromate solution is taken in the burette with constant shaking tillthe dark green colour solution changes to just bluish – violet colour. Note down the burettereading. Repeat the titration to get concordant values. Calculate the normality of potassiumdichromate solution.




3

Part-III: Estimation of iron by stannous chloride reduction method:

Observation:

1) Solution : K 2Cr 2O7 solution

2) Conical flask : 25 cm 3 iron solution + 5 cm 3 conc. HCl + hot SnCl 2

solution + 10 cm3

saturated HgCl 2 solution + 10 cm3

acid mixture

3) Indictor : Diphenylamine

4) End point : Dark green to bluish-violet

5) Gram equivalent mass of Iron ( : 55.85 g

6) Mass of haematite ore taken (w) : ………….g

Tabular column:

Trial No.

Burette Readings

I II III



Volume of K 2Cr 2O7 run down in cm 3

Concordant burette reading ( VK2Cr 2O 7 = ...........cm3 )

Calculation:( N x V )

K2Cr 2O 7= ( N x V )

N

Iron solution

=

( N x V ) _____________

V

K2Cr 2O 7

=

= ............ N

Iron solution

Iron solution Amount of iron present in 250 cm3

of the given solution }=

x E Iron _______________________

4

= ................

= ............... g

Percentage of iron in haematite ore =

MM x 100

___________________

Mass of haematite taken

N Iron solution

NIron solution

=M x 100 __________

w

= ................ %




4

Part-III: Estimation of iron by stannous chloride reduction method: Make up the given iron

ore solution in 250 cm 3 standard flask to the mark with distilled water and shake it well for

uniform concentration. Pipette out 25 cm 3 of this solution into a clean 250 cm 3 conical flask. Add

5 cm 3 of concentrated HCl. Heat the solution nearly to boiling. To the hot solution add stannous

chloride drop by drop from a burette untill the yellow coloured solution turns to colourless. Add

2 drops of stannous chloride in excess to ensure complete reduction. Cool the solution to

laboratory temperature under tap water; add rapidly 10 cm 3 of saturated mercuric chloride

solution. A silky white precipitate is formed (if grey precipitate is formed due to excess of

stannous chloride, reject the solution and repeat the experiment). Add 10 cm 3 of acid mixture

(H2SO 4 and phosphoric acid) and 4-5 drops of diphenylamine indicator. Titrate this solution

against potassium dichromate solution which is taken in the burette with constant shaking till the

dark green colour solution changes to just bluish – violet colour. This is the end point. Note

down the burette reading. Repeat the titration for the concordant values. Calculate the normality

of iron ore solution and then the amount and percentage of iron present in 250 cm 3 of the

solution.

Result: Percentage of iron present in given haematite ore is found to be -----------




5

Part-I: Preparation of standard sodium oxalate solution:-

Observation:

1) Mass of weighing bottle + Na 2C2O4 crystals (

2) Mass of weighing bottle after transferring crystals (

3) Mass of Na 2C2O4 crystals transferred ( (

4) Gram equivalent mass of Na 2C2O4 (

Calculation: Normality of sodium oxalate solution

Part- II: Standardization of potassium permanganate solution:-

Observation:

1) Burette : KMnO 4 solution2) Conical flask : 25 cm 3 sodium oxalate + 1 test tube full dil. H 2SO 4

3) Indictor : KMnO 4 (self indicator)

4) End point : Colourless to permanent pale pink

Tabular column:

Trial No.

Burette Readings

I II III



Volume of KMnO 4 run down in cm 3

Concordant burette reading ( VKMnO 4 = ...........cm3 )

Calculation:( N x V ) KMnO 4

= ( N x V ) Na 2C 2O 4

N KMnO 4 =( N x V ) Na 2C2O 4 _____________ VKMnO 4

=

= ............ N Normality of potassium permanganate solution = -------------N




6

Experiment No. 2Estimation of calcium in lime stone.

Aim: To estimate the percentage of calcium present in given limestone ore using standard

KMnO 4 solution.

Principle: Calcium is precipitated as calcium oxalate using ammonium oxalate.

CaCO 3 + 2HCl CaCl 2 + H 2O + CO 2CaCl 2 + (NH 4 )2C 2O 4 CaC 2O 4 + 2NH 4Cl

Calcium oxalate is dissolved in hot dilute sulphuric acid and titrate against standard potassium

permanganate solution.

CaC 2O 4 + H 2SO 4 CaSO 4 + H 2C 2O 4

2KMnO 4 + 3H 2SO 4 K2SO 4 + 2MnSO 4 + 3H 2O + 5(O)

[H2C 2O 4 + (O) 2CO 2 +H 2O ] x 5

2KMnO 4 + 3H 2SO 4 + 5 H 2C 2O 4 K2SO 4 + 2MnSO 4 + 10CO 2 + 8H 2O

Procedure: Part-I: Preparation of standard sodium oxalate solution:- Weigh accurately

(1.67 g) the given sodium oxalate crystals and transfer into a 250 cm 3 standard flask. Add 3-4

drops of concentrated H 2SO 4 and dissolve in distilled water and make up the solution upto the

mark and shake well for uniform concentration. Calculate the normality of the sodium oxalate

solution prepared.

Part- II: Standardization of potassium permanganate solution:- Pipette out 25 cm 3 of

prepared sodium oxalate solution into a clean 250 cm 3 conical flask. Add 1 test tube full dilute

H2SO 4 and heat nearly to boiling. Titrate this hot solution against KMnO 4 solution ( Add first 2cm 3 of KMnO 4 drop wise ) which is taken in the burette with constant shaking till a permanent

pale pink coloured solution is obtained. Note down the burette reading. Repeat the titration to get

concordant values. Calculate the normality of KMnO 4 solution.




7

Part-III: Estimation of calcium:

Observation:

1) Burette : KMnO 4 solution

2) 400 cm 3 beaker : Precipitate along with filter paper + 30 cm 3

of dilute H 2SO 4 3) Indictor : KMnO 4 (self indicator)


5) Gram equivalent mass of calcium ( : 20 g

6) Mass of lime stone taken (w) : ………….g

Tabular column:

Trial No.

Burette Readings

I II III






KMnO 4= ( N x V )

N

Calcium solution

=

( N x V ) _____________

V

KMnO 4

=

= ............ N

Calcium solution

Calcium solution Amount of calcium present in 250 cm

3

of the given solution }=x E Calcium _______________

4= ................

= ............... g

Percentage of calcium in lime stone =

M

M x 100 ___________________ Mass of lime stone taken

NCalcium solution

NCalcium solution

=M x 100

__________ w

=............... %




8

Part-III: Estimation of calcium:

Make up the given limestone solution in 250 cm 3 standard flask to the mark with distilled water

and shake it well for uniform concentration. Pipette out 25 cm3

of this diluted solution into a

clean 400 cm 3 beaker. Add 2 – 3 drops of methyl orange indicator. The solution turns to red. Add

ammonium hydroxide solution drop wise till the red coloured solution turns to yellow. Heat the

solution nearly to boiling. To the hot solution add 30 cm 3 of 3% hot ammonium oxalate solution

slowly with constant stirring. If the solution is not yellow add ammonium hydroxide drop wise

till it turns to yellow (solution smells ammonia). Allow the precipitate to stand for about 15

minutes. Test for completion of precipitation by adding little hot ammonium oxalate along the

sides of the beaker. Filter the precipitate through a quantitative filter paper (Whatmann –

42).Wash the precipitate 4 – 5 times with small portions of cold water until the last washing is

free from chloride ions (test with silver nitrate solution). Transfer the precipitate along with filter

paper into the same beaker in which the precipitation was carried out. Add 30 cm 3 of 3% dilute

sulphuric acid, heat nearly to boiling. Titrate the hot solution against standardized potassium

permanganate solution taken in the burette till the solution just turns permanent pale pink.

Calculate the normality of calcium solution and then the amount and percentage of calcium in

the given sample of ore.

Result: Percentage of calcium present in given limestone is found to be -----------




9

Part-I: Preparation of standard potassium dichromate solution:-Observation:

1) Mass of weighing bottle + K 2Cr 2O7 crystals ( 2) Mass of weighing bottle after transferring the crystals ( 3) Mass of K 2Cr 2O7 crystals transferred ( (

4) Gram equivalent mass of K 2Cr 2O7 ( Calculation:

Normality of potassium dichromate solution (

Part- II: Standardization of sodium thiosulphate solution:-

Observation:1) Burette : Na 2S2O3 solution2) Conical flask : 25 cm 3 K 2Cr 2O7 + 5 cm 3 conc. HCl + 10 cm 3 of 10% KI solution

3) Indictor : Starch (4 – 5 drops near to the end point)4) End point : Disappearance of blue colourTabular column:

Trial No.Burette Readings

I II III



Volume of Na 2S2O3 run down in cm

Concordant burette reading ( VNa 2S 2O 3= ...........cm

3 )

Calculation:( N x V ) Na 2S 2O 3

= ( N x V ) K2Cr 2O 7

N Na 2S 2O 3=

( N x V ) K2Cr 2O 7 _____________ VNa 2S 2O 3

=

= ............ N Normality of sodium thiosulphate solution = -------------N




10

Experiment No. 3

Estimation of copper in brass.

Aim: To estimate the percentage of copper present in given sample of brass using standard

sodium thiosulphate solution.Principle: Brass is an alloy of mainly copper and zinc (80% +20%), copper in brass is estimated

iodometrically.

(i) A known volume of potassium dichromate is treated with KI in presence of HCl, iodine is

liberated.K2Cr 2O 7 + 8HCl 2KCl + 2CrCl 3 + 4H 2O + 3(O)

[ KI + HCl HI + KCl ] x 6

[ 2HI + (O) I2 + H 2O ] x 3

K2Cr 2O 7 + 6KI + 14 HCl 8KCl + 2CrCl 3 + 3I 2 + 7H 2O The liberated iodine is titrated with sodium thiosulphate using starch as indicator.

I2 + 2Na 2S 2O3 2NaI + Na 2S 4O6 (ii) A known mass of brass is dissolved in 1:1 nitric acid. A known volume of brass solution is

treated with potassium iodide in acidic medium, iodine is liberated.Cu + 4HNO 3 Cu(NO 3)2 + 2NO 2 + 2H 2O

2Cu(NO 3)2 + 4KI 2CuI + I 2 + 4KNO 3

The liberated iodine is titrated with standard sodium thiosulphate using starch indicator.Procedure: Part-I: Preparation of standard potassium dichromate solution:- Weigh

accurately (1.25 g) the given potassium dichromate crystals and transfer into a 250 cm 3 standard

flask. Dissolve in distilled water and make up the solution up to the mark and shake well for

uniform concentration. Calculate the normality of the potassium dichromate solution prepared.Part- II: Standardization of sodium thiosulphate solution:- Pipette out 25 cm 3 of prepared

potassium dichromate solution into a clean 250 cm 3 conical flask. Add about 5 cm 3 ofconcentrated HCl followed by 10 cm 3 of 10% KI solution and immediately close with watchglass. The solution turns brown due to the liberation of iodine. Shake and keep aside for about 5minutes. Wash down the underside of the watch glass with distilled water and collect thewashings in the same conical flask. Dilute the solution by adding 1 test tube distilled water.Titrate the solution against sodium thiosulphate solution taken in the burette with constantshaking till the solution becomes straw yellow. At this stage add about 4-5 drops of freshly

prepared starch indicator, deep blue colour produced. Continue the titration by adding sodiumthiosulphate solution in drops till the blue colour just disappears. Note down the burette reading.Repeat the titration for concordant values. Calculate the normality of Na 2S2O3 solution.




11

Part-III: Estimation of copper:

Observation:

1) Burette : Na 2S2O3 solution

2) Conical flask : 25 cm3

copper solution + NH 4OH +CH 3COOH + 10 cm 3 of 10% KI

3) Indictor : Starch (4 – 5 drops near to the end point)

4) End point : Disappearance of blue colour5) Gram equivalent mass of copper ( : 31.75 g

6) Mass of brass alloy taken (w) : ………….g

Tabular column:

Trial No.

Burette Readings

I II III



Volume of Na 2S2O3 run down in cm 3

Concordant burette reading ( VNa 2S 2O 3= ...........cm

3 )


Na 2S 2O 3= ( N x V )

N

Copper solution

=

( N x V ) _____________

V

Na 2S 2O 3

=

= ............ N

Copper solution

Copper solution Amount of copper present in 250 cm

3

of the given solution}=

x E Copper _______________

4= ................

= ............... g

Percentage of copper in brass =

M

M x 100 ___________________

Mass of brass alloy taken

= ..............

N Copper solution

NCopper solution

%

=M x 100

w




12

Part-III: Estimation of copper:

Make up the given brass solution upto the mark with distilled water and shake it well for

uniform concentration. Pipette out 25 cm 3 of this diluted solution into a clean 250 cm 3 conical

flask. Add ammonium hydroxide solution drop wise until a pale blue coloured precipitate of

cupric hydroxide is formed. Dissolve the precipitate by adding 2N acetic acid. Add 5 cm 3 of

acetic acid in excess. Add 10 cm 3 of 10% KI solution and immediately close the mouth of

conical flask with watch glass. The solution turns brown due to the liberation of iodine. Shake

and keep aside for about 5 minutes. Wash down the underside of the watch glass with distilled

water and collect the washings in the same conical flask. Titrate the solution against standardized

sodium thiosulphate solution which is taken in the burette with constant shaking till the solution

becomes straw yellow. At this stage add about 4-5 drops of freshly prepared starch indicator,

deep blue colour produced. Continue the titration by adding sodium thiosulphate solution in

drops till the blue colour just disappears. Note down the burette reading. Repeat the titration for

the concordant values. Calculate the normality of copper (brass) solution and then amount and

percentage of copper in the given sample of brass alloy.

Result: Percentage of copper present in given brass is found to be -----------




13

Part-I: Preparation of standard zinc sulphate solution:-

Observation:

1) Mass of weighing bottle + ZnSO 4.7H 2O crystals (

2) Mass of weighing bottle after transferring the crystals (

3) Mass of ZnSO 4.7H 2O crystals transferred ( (

4) Gram molecular mass of ZnSO 4.7H 2O (

Calculation:Molarity of Zinc sulphate solution (

Part- II: Standardization of EDTA solution:-

Observation:

1) Burette : EDTA Solution2) Conical flask : 25 cm 3 zinc sulphate + 2 cm 3 buffer solution

3) Indictor : Eriochrome Black - T

4) End point : Wine red to just blue

Tabular column:

Trial No.

Burette Readings

I II III



Volume of EDTA run down in cm 3

Concordant burette reading ( V EDTA = ...........cm3 )

Calculation:( M x V ) EDTA

= ( M x V ) ZnSO 4

MEDTA =( M x V ) ZnSO 4 _____________ VEDTA

=

= ............ M Molarity of EDTA solution = -------------M




14

Experiment No. 4

Estimation of Zinc using EDTA.

Aim: To estimate the amount of zinc present in 250 cm 3 of the given Zinc sulphate solution

using standard EDTA solution and Eriochrome black – T indicator.

Procedure: Part-I: Preparation of standard Zinc sulphate solution:- Weigh accurately (0.72

g) the given Zinc sulphate crystals and transfer into a 250 cm 3 standard flask. Add few drops of

concentrated H 2SO 4 and dissolve in distilled water and make up the solution upto the mark and

shake well for uniform concentration. Calculate the molarity of the zinc sulphate solution

prepared.Part- II: Standardization of EDTA solution:- Pipette out 25 cm 3 of the zinc sulphate solution

prepared into a clean 250 cm 3 conical flask. Add 2 cm 3 of ammonia – ammonium chloride buffer

solution (p H -10) and 4-5 drops of Eriochrome black- T indicator. Titrate this wine red colour

solution against EDTA solution which is taken in the burette with constant shaking until the

colour changes from wine red to just blue. Note down the burette reading. Repeat the titration for

the concordant values. Calculate the molarity of EDTA solution.




15

Part-III: Estimation of zinc in zinc solution:

Observation:

1) Burette : EDTA solution

2) Conical flask : 25 cm 3 Zinc solution+ 2 cm 3 buffer solution

3) Indictor : Eriochrome Black - T4) End point : Wine red to blue

5) Gram atomic mass of zinc ( : 65.4 g

Tabular column:

Trial No.

Burette Readings

I II III





Calculation:( M x V ) = ( M x V )

MEDTA

=

( M x V ) _____________

V

EDTA

== ............ M

Zinc solution

Zinc solutionZinc solution

Molarity of zinc solution = ------------- M

MZinc solution Amount of zinc present in 250 cm

3


x M'' Zinc __________________________

4= ................

= ............... g




16

Part-III: Estimation of zinc in zinc solution:

Make up the given Zinc solution to the mark with distilled water and shake it well for uniform

concentration. Pipette out 25 cm 3 of this solution into a clean 250 cm 3 conical flask. Add 2 cm 3

of ammonia – ammonium chloride buffer (P H=10) solution and 4-5 drops of Eriochrome black- T

indicator. Titrate this wine red colour solution against EDTA solution which is taken in the

burette with constant shaking until the colour changes from wine red to just blue. Note down the

burette reading. Repeat the titration to get concordant values. Calculate the molarity of zinc

solution and then amount present in the 250 cm 3 of the given solution.

Result: Amount of Zinc present in 250 cm 3 of the given zinc solution is found to be ----------- g




17


Observation:


2) Mass of weighing bottle after transferring the crystals (

3) Mass of ZnSO 4.7H 2O crystals transferred ( (


Calculation:

Molarity of Zinc sulphate solution (


Observation:


2) Conical flask : 25 cm 3 zinc sulphate + 2 cm 3 buffer solution


4) End point : Wine red to just blue

Tabular column:

Trial No.

Burette Readings

I II III






= ( M x V ) ZnSO 4

MEDTA

=( M x V ) ZnSO 4 _____________ VEDTA

=

= ............ M

Molarity of EDTA solution = ------------- M




18

Experiment No. 5

Estimation of total hardness of water using EDTA.

Aim: To estimate the total hardness of water in terms of calcium carbonate present in the given

water sample using standard EDTA solution and Eriochrome black – T indicator.

Principle: Hardness of water is due to the dissolved salts of Calcium and Magnesium present in

water. Hardness of water is expressed in terms of parts of calcium carbonate present in one

million parts of water (ppm). Hardness of water is determined by titrating a known volume of

sample of hard water against standard EDTA using Eriochrome black T as indicator.

Procedure: Part-I: Preparation of standard zinc sulphate solution:- Weigh accurately

(0.72 g) the given Zinc sulphate crystals and transfer into a 250 cm 3 standard flask. Add few

drops of of concentrated H 2SO 4 and dissolve in distilled water and make up the solution upto the

mark and shake well for uniform concentration. Calculate the molarity of the zinc sulphate

solution prepared.

Part- II: Standardization of EDTA solution:- Pipette out 25 cm 3 of the Zinc sulphate solution


(pH =10) solution and 4-5 drops of Eriochrome black- T indicator. Titrate this wine red colour







19

Part- III: Estimation of total hardness of given sample of water:-

Observation:


2) Conical flask : 25 cm 3 hard water + 2 cm 3 buffer solution

3) Indictor : Erichrome Black – T4) End point : Wine red to just blue

5) Gram molecular mass of CaCO 3 ( ) : 100 g

Tabular column:

Trial No.

Burette Readings

I II III





Calculation:( M x V ) = ( M x V )

MEDTA

=

( M x V ) _____________

V

EDTA

=

= ............ M

Hard w ater

Hard w ater Hard w ater

Molarity of given sample of hard water = -------------M

MHard w ater Amount of CaCO 3 present in 1 litre

of the given solution}= x M''

= ................

= ............... g(M)

Hardness of w ater in terms of CaCO 3 = M x 10 3 ppm

= ...... ppm




20

Part-III: Estimation of total hardness of water:

Pipette out 25 cm 3 of given sample of hard water into a clean 250 cm 3 conical flask. Add 2 cm 3

of ammonia – ammonium chloride buffer (pH =10) solution and 4-5 drops of Eriochrome black-

T indicator. Titrate this wine red colour solution against standardized EDTA solution taken in the

burette with constant shaking until the colour changes from wine red to just blue. Note down the

burette reading. Repeat the titration for the concordant values. Calculate the molarity of hard

water and then amount in terms of calcium carbonate.

Result: Total hardness of the given sample of water in terms of calcium carbonate is found to be

----------- ppm




21

Observations:

1) Mass of empty silica crucible (W 1) = ---------------g

2) Mass of silica crucible + BaSO 4 precipitate. (W 2) = --------------g

3) Mass of Barium sulphate (W) = (W 2 – W1)

= --------------g

Calculations:

BaSO 4 BaCl 2.H2O Ba

Molecular mass- 233.43g 244.31g 137.36g

233.43 g of BaSO 4 contains 137.36 g of barium

W g of BaSO4 contains

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

(M) = ------------g

i. e. Amount of barium present in 25 cm 3 of the given solution (M) = --------g

Amount of barium present in 250 cm 3 of the given solution = (M) x 10

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

= -------------- g




22

Experiment No. 6Gravimetric estimation of barium as barium sulphate.

Aim: To estimate the amount of barium as barium sulphate in barium chloride gravimetrically.

Principle: Precipitation is done by adding hot dilute H 2SO 4 (0.5M) to a hot solution of barium

salt. The reaction in case of BaCl 2 solution is:BaCl 2 + H 2SO 4 BaSO 4 + 2HCl

Barium sulphate has very low solubility in water (about 3 mg per litre at room temperature). The

presence of mineral acid increases the solubility due to formation of acid sulphate in HSO 4-.

Even then, the precipitation is done in weakly acid medium to prevent the precipitation ofcarbonate, chromate and phosphate. Acid decomposes carbonate and chromate. The phosphateremains soluble in acidic medium. To avoid co-precipitation, both, salt solutions as well asH2SO 4 are kept hot. BaCl 2 and Ba(NO 3)2 may be precipitated and to avoid these, precipitant isadded slowly with constant stirring. The precipitate is washed with cold water.BaSO 4 is not easily decomposed. It decomposes at 1400 0C as follows.

BaSO 4 1400

0C

BaO + SO 3 But here due to carbon of the filter, it is reduced just above 600 0C

BaSO 4 + 4C BaS + 4CO During ignition of the filter paper, care is taken that the filter paper should be charred withoutinflaming and in ample supply of oxygen to convert most of the carbon to carbon dioxide. Smalltreatment by adding concentrated HCl and then concentrated H 2SO 4 and heat gently so that whitefumes are removed.Procedure: Dilute the given solution of BaCl 2 by adding equal volume of distilled water. Makethe solution slightly acidic by adding 5 cm 3 of dil. HCl. Heat it to boiling and add to it hot dil.H2SO 4 slowly with constant stirring with a glass rod. A white precipitate is formed. Allow the

precipitate to settle down until supernatant liquid becomes clear. Add a little more of diluteH2SO 4 by the side of the beaker to see whether the precipitation is complete or not. If thesupernatant liquid gives white precipitate, add more of dilute H 2SO 4 and allow the solution to

become clear and test it again. Repeat this process till the supernatant liquid gives no precipitate.Avoid use of dilute H 2SO 4 in excess. Cover the beaker by watch glass and heat (but not to

boiling) for about half an hour to digest the precipitate. Decant the clear liquid through a filter paper (Whatman No. 42) and wash the precipitate by decantation with hot water and test for Cl -

and SO 42- ions in the filtrate. After repeated washing, if the last filtrate does not give white

precipitate with AgNO 3 or BaCl 2 solution, the Cl - and SO 42- ions are considered to be removed.

Transfer the precipitate on filter paper. Use policeman to remove any precipitate sticking on thewall of beaker.

Dry the filter paper on chimney or in electrical oven. When the precipitate gets dried, keepingthe precipitate inside, fold the filter paper in the form of a packet and put it in the crucible. Ignitethe filter paper over low flame but do not allow the filter paper to burn with flames. When thefilter paper is completely charred, raise the flame of the burner to burn off carbon to clear ash.Cool the crucible, add one drop of concentrated HCl and one drop of concentrated H 2SO 4 andheat the crucible gently so that white fumes are removed. Now heat the crucible strongly andthen cool it in air. Put the crucible in desiccator and weigh accurately.Result: Amount of barium present in 250 cm 3 of the given solution is found to be ------------g




23

Observations:

1) Mass of empty silica crucible (W 1) = ---------------g

2) Mass of silica crucible + Ni (DMG) 2 precipitate (W 2) = --------------g

3) Mass of Ni(DMG) 2 precipitate (W) = (W 2 – W1)

= --------------g

Calculations:

Ni(DMG) 2 Ni

Molecular mass- 289 g 59 g

289 g of Ni(DMG) 2 contains 59 g of nickel

W g of Ni(DMG) 2 contains

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

(M) = ------------g

i.e. Amount of nickel present in 25 cm 3 of the given solution (M) = --------g

Amount of nickel present in 250 cm 3 of the given solution = (M) x 10

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

= -------------- g




24

Experiment No. 7

Gravimetric estimation of nickel as nickel dimethyl glyoximate.

Aim: To estimate the amount of nickel as nickel dimethyl glyoximate gravimetrically.

Principle: Nickel is precipitated as nickel dimethyl glyoximate by the addition of alcoholic

dimethyl glyoxime and ammonium hydroxide to a hot nickel salt solution.

Ni2+

+CH3 C N OH

CCH3 N OH

Dimethyl glyoxime

CH3 C N

O

CCH3 N

O

NiN C CH 3

N C CH 3

O

OH

+ 2H+

Nickel dimethyl glyoximate

H

Procedure: Make up the given nickel solution to the mark in 250 cm 3 standard flask and shake

well for uniform concentration. Pipette out 25 cm 3 of the above solution into a 400 cm 3 beaker.

Add 5 cm 3 of dilute HCl and 2 test tubes distilled water. Heat the solution nearly to boiling. To

the hot solution add 20 cm 3 of 1% dimethyl glyoxime, followed by 4N ammonia solution drop

by drop with constant stirring until precipitation occurs; add ammonia in slight excess. Digest the

precipitate over hot water bath for about 30 minutes. Allow the precipitate to settle for an hour.

Test the supernatant solution for complete precipitation.

Filter the precipitate through a previously weighed sintered glass crucible. Wash the

precipitate with cold water till the last drops of washings are free from chloride. Dry the

precipitate at 110 to 120 0C in a hot air oven for about one hour. Cool and dry the precipitate in a

decicator and weigh. Repeat drying and weighing for constant weights.

Result: Amount of nickel present in 250 cm 3 of the given solution is found to be ------------g.




25

Tabular column:

Wavelength in nm Absorbance (O.D.)

450470

510

520

540

570

600

670

Value of wavelength at maximum absorbance gives max = -------------- nm

= --------- x 10 A 0

= …………. x 10 -10 m

In [Cu (NH 3)4] SO 4 complex, copper is in +2 oxidation state and it has square planar structure.

Hence crystal field splitting energy diagram can be show in figure.

E n e r g y

dxy d xz d yz

dxz d yz

d z2

dxy

x2 - y 2

dz

2 dx

2

- y2

Cu(II)complex

- 0.51

- 0.43 o

+ 0.23 o

+1.23o

......................................................

t2g

e g

...............

....................

- 0.4

+0.6




26

Experiment No. 8

Preparation of cuprammonium sulphate and determination of max and hence CFSE.

Aim: To prepare cuprammonium sulphate and determine the max and hence calculate the CFSE.

Principle: When an electromagnetic radiation is passed through a sample, certain characteristic

wavelengths are absorbed by the sample. As a result the intensity of the transmitted light is

decreased. The measurement of the decrease in intensity of radiation is the basis of

spectrophotometry. Thus the spectrophotometer compares the intensity of the transmitted light

with that of incident lights. The absorption of light by a substance is governed by Beer’s and

Lambert’s law. Acco rding to the Beer- Lambert’s law; when a beam of monochromatic light of

intensity I 0 passes through a medium that contains an absorbing substance, the intensity of

transmitted radiation I depends on the length of the absorbing medium and the concentration of

the solution. Mathematically it can be represented as:

Absorbance = log (I 0/I) = εc l Where, I 0 = intensity of incident light I = intensity of transmitted

light A = absorbance l = length of the absorbing medium c = concentration of the solution ε =

molar absorption coefficient or molar extinction coefficient. The molar absorption coefficient or

molar extinction coefficient is the absorbance of a solution having the unit concentration (c =

1M) placed in a cell of unit thickness ( l = 1 cm). Absorbance is also called optical density

(OD).Thus, for a particular wavelength λ, the absorbance or OD of a sol ution in a container of

fixed path length is directly proportional to the concentration of a solution. i. e. A ∞ c

The wavelength at which the densest solution of the complex gives maximum optical

density(O.D. ) is called λmax, using λmax, the crystal field splitting energy is calculated and

hence the CFSE of the complex.




27

Calculation:

Crystal field splitting energy of

cuprammonium sulphate } ( E) =N0 x h x c

max

=6.023 x 10 23 x 6.626 x 10 -34 x 3 x 10 8

max

=----------- kj ---

Therefore,

Crystal field stabilization energy

of cuprammonium sulphate } (CFSE) =

=

-1.21 ( o )

--------------

= ------------- kj Note : 1 kj mol -1 = 83.6 cm -1




28

Procedure: Part – I: Preparation of cuprammonium sulphate:

5 g of copper sulphate (finely powdered) is taken in a beaker and is dissolved in minimum

quantity of water containing a few drops of H 2SO 4. To it liquor ammonia is added drop by drop

from a dropping funnel till the blue precipitate formed is dissolved with the formation of a deep

blue coloured solution.

To this blue coloured solution 50 cm 3 of rectified spirit is slowly added with constant

stirring. The beaker is covered with a watch glass and allowed to stand for 15 minutes. Long

needle shaped blue crystals of the dried compound are separated out. It is filtered and washed

with a few drops of rectified spirit and dried in the desiccators.

The yield is obtained --------------- g (7 g)

Part - II: Determination of : Above prepared 0.4 g of cupraammonium sulphate crystals

is accurately weighed and transferred into a 100 cm 3 standard flask. The crystals are dissolved in

a small quantity of distilled water and make up the solution up to the mark with distilled water

and shaken well for uniform concentration. Absorbance (optical density) of this solution is

measured at different wavelength in a colorimeter against blank. The wavelength which gives

maximum optical density is the . By knowing the value, CFSE of cupraammonium

sulphate is calculated.

Result: The crystal field stabilization energy of the cuprammonium sulphate complex is found

to be ----------- kj.




29

(i) Preparation of standard sodium oxalate solution:-

See page No. 35

(ii) Standardization of potassium permanganate solution:-Observation:

1) Burette : KMnO 4 solution

2) Conical flask : 25 cm 3 sodium oxalate + 1 test tube full dil. H 2SO 4



Tabular column:

Trial No.

Burette Readings

I II III






= ( N x V ) Na 2C 2O 4

N KMnO 4 =( N x V ) Na 2C2O 4 _____________ VKMnO 4

=

= ............ Na Mass of the complex taken (W) = …………. g

Let the volume of ‘a’ N KMnO 4 used up (V) = ………. cm 3

1 cm3

of 0.1N KMnO 4 0.005585 g

Then 1 cm 3 of ‘a’N KMnO 4

--------- (z)

V cm 3 of ‘a’ N KMnO 4 (z X V) = ……….. g (A)




30

Percentage of iron = ( )

Experiment No. 9

Preparation of sodium trioxalatoferrate(III) and estimation of iron.

Aim: To prepare the sodium trioxalatoferrate (III) and determine the percentage of iron present

in the complex.

Part-1: Preparation of hydrated ferric oxide: In a beaker 7.5 g of ferric chloride is dissolved

in 5 cm 3 of water. To it 6 g of sodium hydroxide dissolved in 5 cm 3 of water is added little at a

time with stirring. It is allowed to stand for 5 minutes. The precipitate of ferric hydroxide,

Fe(OH) 3 formed, is filtered and washed 5-6 times with hot water.

Part-2: Preparation of sodium trioxalatoferrate (III): In a beaker 9.0 g of oxalic acid is taken

and is dissolved in 30 cm 3 of hot water. To it 3 g of sodium hydroxide is added and shaken well.

To this hot alkaline solution ferric hydroxide (hydrated ferric oxide) prepared earlier is added in

small portions with constant stirring when green solution of the desired compound is formed.

The solution is filtered and filtrate is concentrated in a silica dish on a water bath. Green crystals

of sodium trioxalatoferrate(III) are formed. It is filtered and dried by soaking through blotting

paper.

The yield is obtained ---------- g (15g)

Part-3: Estimation of iron:

About 1 g of the above compound is weighed and treated with 2 -3 cm 3 of concentrated sulphuric

acid in a porcelain dish covered with a watch glass. The solution is gently heated till the

effervescence due to decomposition of oxalate stops. It is then cooled and the contents are

transferred into a conical flask. To this 2 g of zinc dust and 10 cm 3 of dilute sulphuric acid is

added and boiled for 15 -20 minutes to reduce ferric ions to ferrous ions. The unreacted zinc is

removed by filtration. The filtered solution is titrated with decinormal KMnO 4 solution till a permanent pale pink coloured solution is obtained.

2KMnO 4 +8H 2SO 4 +10FeSO 4 K2SO 4 + 2MnSO 4 + 5Fe 2 (SO 4)3 +8H 2O

Result: The percentage of iron present in the complex is found to be ---------------




31


Observation:


2) Mass of weighing bottle after transferring the crystals ( 3) Mass of ZnSO 4.7H 2O crystals transferred ( (


Calculation:Molarity of Zinc sulphate solution (


Observation:1) Burette : EDTA Solution

2) Conical flask : 25 cm 3 zinc sulphate + 2 cm 3 buffer solution

3) Indictor : Eriochrome Black – T

4) End point : Wine red to blue

Tabular column:

Trial No.

Burette Readings

I II III




Concordant burette reading ( V EDTA = (x) = ...........cm3 )


= ( M x V ) ZnSO 4

MEDTA =

( M x V ) ZnSO 4 _____________ VEDTA

=

= ............ M Molarity of EDTA solution = -------------M




32

Experiment No. 10

Estimation of nickel using EDTA and standard zinc sulphate.

Aim: To estimate the amount of nickel present in 250 cm3

of the given nickel solution using

standard EDTA solution and Eriochrome black – T indicator.

Procedure: Part-I: Preparation of standard zinc sulphate solution:- Weigh accurately (0.72

g) the given zinc sulphate crystals and transfer into a 250 cm 3 standard flask. Add few drops of

concentrated H 2SO 4 and dissolve in distilled water and make up the solution upto the mark and

shake well for uniform concentration. Calculate the molarity of the zinc sulphate solution

prepared.

Part- II: Standardization of EDTA solution:- Pipette out 25 cm 3 of the zinc sulphate solution


solution (p H -10) and 4-5 drops of Eriochrome black- T indicator. Titrate this wine red colour







33

Part – III: Estimation of nickel in nickel solution by back titration:

Observation:

1) Burette : ZnSO 4 solution

2) Conical flask : 25 cm 3 nickel solution + 2 cm 3 buffer solution

3) Volume of EDTA added (a) : --------------- cm3


4) End point : Blue to just wine red

5) Gram atomic mass of nickel ( : 58.7 g

Tabular column:

Trial No.

Burette Readings

I II III



Volume of ZnSO 4 run down in cm 3

Concordant burette reading ( VZnSO 4= ...........cm

3 ) = (y)

Calculation: 25 cm 3 of std. ZnSO 4 solution reacts with ‘x’ cm 3 of EDTA solution

‘y’ cm 3 of std. ZnSO 4 solution reacts =

cm 3 of EDTA solution

(b) = …….. cm 3 of EDTA

Volume of EDTA reacted with nickel ( = (a – b)

= ………… cm 3

( M x V ) = ( M x V )

MEDTA

=

( M x V ) _____________

V

EDTA

=

= ............ M

Nickel solution

Nickel solutionNickel solution

Molarity of nickel solution = ------------- M

M Nickel solution Amount of nickel present in 250 cm

3


x M' Nickel __________________________

4= ................

= ............... g




34

Part-III: Estimation of nickel in nickel solution by back titration:

Make up the given nickel solution to the mark in a 250 cm 3 standard flask with distilled water

and shake it well for uniform concentration. Pipette out 25 cm 3 of this solution into a clean 250

cm 3 conical flask. Add standardized EDTA solution from burette in excess (about 30 -35 cm 3);

(a = ------cm 3). Add 2 cm 3 of ammonia – ammonium chloride buffer (pH =10 ) solution and 4-5

drops of Eriochrome black- T indicator. Titrate this blue colour solution against standard zinc

sulphate solution which is taken in the burette with constant shaking until the colour changes

from blue to just wine red. Note down the burette reading. Repeat the titration for the concordant

values. Calculate the molarity of nickel solution and then amount.

Result: Amount of nickel present in given nickel solution is found to be -----------g




35

Part-B: Analysis of ferrous oxalate:

(i) Preparation of standard sodium oxalate solution:-

Observation:

1) Mass of weighing bottle + Na 2C2O4 crystals (

2) Mass of weighing bottle after transferring crystals ( 3) Mass of Na 2C2O4 crystals transferred ( (

4) Gram equivalent mass of Na 2C2O4 (

Calculation: Normality of sodium oxalate solution

(ii) Standardization of potassium permanganate solution:-

Observation:1) Burette : KMnO 4 solution

2) Conical flask : 25 cm 3 sodium oxalate + 1 test tube full dil. H 2SO 4



Tabular column:

Trial No.

Burette Readings

I II III






= ( N x V ) Na 2C 2O 4

NKMnO 4

=( N x V ) Na 2C2O 4 _____________

VKMnO 4

=

= ............ N Normality of potassium permanganate solution = -------------N




36

Experiment No. 11

Preparation of ferrous oxalate and its analysis (both iron and oxalate).

Aim: To prepare the ferrous oxalate and estimate the percentage of iron and oxalate present in 50

mg of the prepared ferrous oxalate sample.Principle: (A) Preparation of ferrous oxalate:Ferrous oxalate is prepared by heating oxalic acid solution with ferrous ammonium sulphatesolution acidified with dilute H 2SO 4 as:

(NH 4)2SO 4 FeSO 4 .6H 2O + H 2O 2[NH 4+]aq + 2[SO 4

2-]aq + [Fe 2+]aq

H2C 2O 4 .2H 2O + H 2O 2[H +]aq + [C 2O 42-]aq

[Fe 2+]aq + [C 2O42-]aq + [H +]aq

FeC 2O 4 .2H 2O

(B) Analysis of ferrous oxalate:(i) Standardization of potassium permanganate solution using std. oxalic acid solutionPotassium permanganate is a powerful oxidizing agent and in the presence of dilute H 2SO 4, itoxidizes oxalic acid to carbon dioxide and water.

2MnO 4- + 5C 2O 4

2- + 16H

+ 2Mn2+

+ 8H 2O + 10 CO 2 Acidified KMnO 4 gives oxygen for oxidation according to the following equation:2KMnO 4 + 3H 2 SO 4 2MnSO 4 + K 2SO 4 + 3H 2 O + 5(O) (ii) Estimation of oxalate ion in ferrous oxalate using standardized KMnO 4 solution

2MnO 4

-

+ 5C 2O 4

2-

+ 16H+ 2Mn

2+ + 8H

2O + 10 CO

2

1 cm3 of 0.1N KMnO 4 0.0044 g of C 2O 4

2-

(iii) Estimation of Fe 2+ in ferrous oxalate using standardized KMnO 4 solution

MnO 4- + 5Fe

2+ + 8H

+ Mn2+

+ 4H 2O + 5Fe3+

1 cm3 of 0.1N KMnO 4 0.005585 g of Fe 2+

Overall reaction for estimation:

2MnO4

- + 5C

2O

4

2- + 16H

+ 2Mn2+

+ 8H 2O + 10 CO 2

MnO 4- + 5Fe

2+ + 8H

+ Mn2+

+ 4H 2O + 5Fe3+

3MnO 4- + 5C 2O 4

2- + 5Fe 2+ + 24H + 3Mn2+

+ 12H 2O + 5Fe3+

+ 10CO 2

(iii) Estimation of iron and oxalate:Observations:




37

1) Burette : KMnO 4 solution2) Conical flask : 0.5 g of ferrous oxalate + 10 cm 3 of 20% H 2SO 4 3) Indictor : KMnO 4 (Self indicator)4) End point : Colourless to permanent pale pinkTabular column:

Trial No.Burette Readings

Oxalate[C 2O4-] Iron(Fe +)

I II III I II III


Initial Burette Reading ------ ------- --------

Volume of KMnO 4 run down incm 3

------- ------- --------

x = ----------cm 3 y = ----------cm 3 Calculations:

1000 cm 3 of 1N KMnO 4 = 44g of (C 2O4)2- 1 cm 3 of 0.1N KMnO 4 = 0.0044g of (C 2O4)2-

Then, 1 cm 3 of ‘a’ N KMnO 4 contains =

-------(z)g of (C 2O4)2-

Volume of (C 2O4)2- = x cm 3

x cm 3 of ‘a’ N KMnO 4 = x X z=

b = ---------- g of oxalate0.5 g of ferrous oxalate = b g oxalate

100 g of ferrous oxalate =

= ------ %Volume of Fe 2+ = y cm 3 1 cm 3 of 0.1N KMnO 4 = 0.005585g of Fe

Then, 1 cm 3 of ‘a’ N KMnO 4 contains =

-------(n)g of (C 2O4)2-

y cm3

of ‘a’ N of KMnO 4 = y X n= ----------c = -------------g of iron

0.5 g of ferrous oxalate = c g iron

100 g of ferrous oxalate =

= --------- %




38

Procedure: Part -A: Preparation of ferrous oxalate:- 3 g of ferrous sulphate is taken in 100cm 3 beaker, 2-3 drops of 2N sulphuric acid is added to make a paste. To this paste hot water isadded to dissolve the crystals. 15 cm 3 of 10% oxalic acid is added to the hot solution and boiled,yellow precipitate of ferrous oxalate is obtained.Part – B: Analysis of ferrous oxalate: (i) Preparation of standard sodium oxalate solution:- Weigh accurately (1.67 g) the givensodium oxalate crystals and transfer into a 250 cm 3 standard flask. Add 3-4 drops of concentratedH2SO 4 and dissolve in distilled water and make up the solution upto the mark and shake well foruniform concentration. Calculate the normality of the sodium oxalate solution prepared.(ii) Standardization of potassium permanganate solution:- Pipette out 25 cm 3 of preparedsodium oxalate solution into a clean 250 cm 3 conical flask. Add 1 test tube full dilute H 2SO 4 andheat nearly to boiling. Titrate this hot solution against KMnO 4 solution ( Add first 2 cm 3 ofKMnO 4 drop wise ) which is taken in a burette with constant shaking till a permanent pale pinkcoloured solution is obtained. Note down the burette reading. Repeat the titration for the

concordant values. Calculate the normality of KMnO 4 solution.(iii) Estimation of iron and oxalate:- 0. 5g of ferrous oxalate is weighed and transferred into250 cm 3 conical flask. 10 cm 3 of 10% dilute H 2SO 4 is added. The solution is heated about 60 0Cand titrated against potassium permanganate till a pale pink colour is obtained. Burette reading isnoted as ‘ x’ cm 3. Now 2g of zinc piece followed by 25 cm 3 of H 2SO 4 is added and boiled tillclear solution is formed. The hot solution is treated against standard KMnO 4 solution till the pinkcolour is obtained. The reading is noted as ‘ c’ cm 3. Repeat the titration for the concordant

burette reading. The difference of values of x and c we get value of ‘ y’ cm 3.

Result:

1) Percentage of iron present in 0.5g of ferrous oxalate sample is ------------ g2) Percentage of oxalate present in 0.5g ferrous oxalate sample is ------------ g




39

Scheme of Practical ExaminationVI Semester B.Sc., Chemistry Practical-7 (INORGANIC)

Max. Marks: 30 Time: 3 Hrs.I. Allocation of marks:Records 5 MarksProcedure writing PART - A 5 MarksMarks for performing experiment PART - B 20 Marks

II. Any one of the following experiments shall be given for procedure writing. The studentshould answer this question at the beginning of the Practical examination. Procedure writingshall include principle or chemical equations and calculations/ sample graph. Maximum timeallowed shall be 20 minutes.

1. Preparation of cupra mmonium sulphate and determination of λ max and CFSE.2. Preparation of sodiumtrioxalatoferrate(III) and estimation of iron.

3.

Preparation of ferrous oxalate and its analysis.III. Any one of the following experiments shall be set for the students to perform:Volumetric analysis Sl.

No.Experiment Standard solution (to

be prepared by thestudents)

Link solution (to be givento the students)

1 Estimation of iron in haematite(using diphenylamine as internalindicator)

Ferrous ammoniumsulphate (reduction

by SnCl 2)

Potassium dichromate orceric ammonium sulphate

2 Estimation of zinc Zinc sulphate EDTA3 Estimation of nickel Zinc sulphate EDTA4 Estimation of calcium in limestone Sodium oxalate Potassium permanganate

5 Estimation of copper in brass Potassiumdichromate

Sodium thiosulphate

Gravimetric analysis1. Estimation of nickel as nickel dimethyl glyoximate.2. Estimation of barium as barium sulphate.

Scheme of Practical Examination ValuationI. Assignment of marks for Practical Record:

Recording of 8 or more experiments 5 MarksRecording of 6-7 experiments 4 MarksRecording of 4 -5 experiments 3 MarksRecording below 4 experiments zero

Note: # 1 mark may be deducted in case of adverse remarks by the teacher in charge.# Record should be valued only if it has been certified by teacher in charge and Head of theDepartment.




40

II. Procedure writing: 5 Marks

Principle or equation: 1 Mark

Procedure: 2 Marks

Calculations: 2 Marks

III. Assignment of marks for the experiment: Performing the experiment: 16 Marks

Volumetric Analysis

Standardization of link solution: 7 Marks Estimation of the given solution: 9 Marks

Error (cm3

) + 0.2 + 0.3 + 0.4 + 0.5

Any other

Value

Marks

Standardization 7 6 5 4 2

Estimation 9 8 7 6 3

Calculation Calculation

Normality of the solution prepared 1 Mark

Normality of link solution 1 Mark

Normality of the solution to be estimated 1 Mark

Amount of the substance or percentage 1 Mark




Gravimetric Analysis

Experiment: 16 Marks Calculations: 4 Marks

Mass of the precipitate (mg) +20 +30 +40 +50 +60

Any other

Value

Marks 16 14 12 10 08 06

Note:

1. Any one experiment to be set either volumetric or gravimetric. A brief procedure must be

provided by the examiner.

2. Examiners have to conduct the experiments and a comparative assessment has to be made.

3. The number of trials in volumetric analysis should not exceed four. The concordant value

should be taken for valuation. If no concordant value is reported, the best value shall be taken

and only 80% of eligible marks shall be awarded.

4. For estimation of calcium, the best value of two determinations shall be considered for

comparative assessment.

5. In gravimetric analysis, one determination should be sufficient.

6. Wherever electronic balances are available, they can be utilized for weighing.

Documents

Vi Semester Manual -1