Experiment-1 ESTIMATION OF FERROUS IRON (Redox Titrations)
Aim: To estimate the amount of Ferrous iron in the whole of the given solution using a standard solution of Potassium Dichromate .
Apparatus: 100 ml standard flask, Burette, 250 ml Conical Flask, 20 ml Pipette, Funnel & Simple balance with Fractional weights .
Chemicals Required: Potassium dichromate (K 2Cr 2O7) Sulphuric acid (H2SO4) Syrupy phosphoric acid (H3PO4) Diphenylamine Ferrous iron solution & distilled water.
Dichromate in acid solution. The Principle: Ferrous Iron is oxidized to Ferric iron by Potassium Dichromate completion of oxidation reaction is marked by the appearance of Blue violet color of Diphenylamine, Diphenylamine, which is used as an internal indicator.
Chemical reactions:
K 2Cr 2O7 + 4H2SO4 2FeSO4 + H2SO4 + (O) K 2Cr 2O7 = 3(O) = 6Fe
K 2SO4 + Cr 2(SO4)3 + 4H2 + 3(O) Fe2(SO4)3 + H2O
Procedure: 1) Preparation of standard potassium dichromate: i) Weigh out accurately the given pure crystalline sample of potassium dichromate and transfer into 100 ml standard (volumetric) flask provided with a funnel.
ii) Dissolve the dichromate in a small quantity of distilled water, and make up to the mark. The contents in the flask are shaken well for uniform concentration.
iii) Calculate the normality of potassium dichromate.
2) Estimation of Iron: i) Make up given solution up to the mark with distilled water and shake the flask for uniform concentration.
ii) Rinse the pipette with the ferrous solution solution and pipette out 20ml into a clean conical flask add 20ml of the acid mixture (sulphuric acid and phosphoric acid), and four to five drop of diphenylamine indicator.
iii) Fill the burette with the prepared potassium dichromate solution after rinsing it, with the same.
iv) Titrate the solution in the conical flask against the standard potassium dichromate from the burette till the color changes to blue violet.
v) Repeat the titrations for concurrent titre values.
Result: Amount of Ferrous iron present in the whole of the given solution (100 ml) = _______ gm
__________________________ _____________________________________________ _____________________________________________________ __________________ Preparation of Standard (K 2Cr2O7) solution: W1 = Weight of bottle + substance (K 2Cr 2O7) = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance (K 2Cr 2O7) = (W1-W2) = ____________ gms. Normality of the K 2Cr 2O7solution = (W1-W2) X 10 / Equivalent Weight
N=
S.No
(W1-W2) X 10 / 49 =
Volume of the standard solution(V2)
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
V2 = 20 ml
Calculation: N1 = Normality of K 2Cr 2O7 solution =
Volume of consume (V1)
Final
N2 = Normality of Ferrous iron solution = ? V1 = Volume of K 2Cr 2O7 solution = V2 = Volume of Ferrous iron solution = 20 ml N1 V1= N2 V2 N2 = N1 V1 / V2 Normality of Ferrous iron solution = N2 = N1 V1/V2 Amount of Ferrous iron present in the whole o f the given solution (100 ml) = N2 X 55.85/10 = Result: Amount of Ferrous iron present in the whole of the given solution (100 ml) = _______ gm.
Experiment-2 ESTIMATION OF FERRIC IRON (Redox Titrations) Aim: To estimate the amount of Ferric iron in the who le of the given solution using a standard solution of Potassium Dichromate. Apparatus: 100 ml standard flask, Burette, Conical Flask, 20 ml Pipette, Simple balance with weights. Chemicals Required: K 2Cr 2O7, SnCl2, HgCl2, HCl, Ferric ion solution, H2SO4, Ortho phosphoric acid, Diphenylamine & distilled water. Principle: Ferric Iron is reduced to ferrous iron by stannous chloride in the present of Hydrochloric acid at a temperature of 70-900C.
The excess stannous chloride is removed by the addition of mercuric chloride. The ferrous iron formed is titrated with standard Potassium dichromate solution in the presence of Sulphuric acid and Phosphoric acid using diphenylamine as indicator. Chemical reactions:
Procedure:
2FeCl3 + SnCl2 SnCl2 + 2HgCl2 K 2Cr 2O7 + 4H2SO4 2FeSO4 + H2SO4 + (O) K 2Cr 2O7 = 3(O) = 6Fe
2FeCl2 + SnCl4 SnCl4 + Hg2Cl2 K 2SO4 + Cr 2(SO4)3 + 4H2O + 3(O) Fe2(SO4)3 + H2O
1) Preparation of standard potassium dichromate: i) Weigh out accurately the given pure crystalline sample of potassium dichromate and transfer into 100 ml standard (volumetric) flask provided with a funnel. ii) Dissolve the dichromate in a small quantity of distilled water, and make up to the mark. iii) The contents in the flask are shaken well for uniform concentration. iv) Calculate the normality of potassium dichromate. 2) Estimation of ferric iron: i) Make up the given ferric iron solution upto the mark of the 100ml standard flask with distilled water and shake well for uniform concentration. ii) Pipette out 20ml of the ferric solution into a clean conical flask and 10ml of conc. iii) HCl and heat the solution to boiling. The colour of the solution changes to clear yellow. iv) Add stannous chloride solution drop by drop into the hot iron solution from a burette till the yellow colour disappears. v) Cool the solution under a tap and add 10 ml of saturated solution of mercuric chloride in one portion silky white precipitate of mercurous chloride is obtained,(if the solution turns black, due to formation of finely divided mercury, discard the solution and take fresh solution of ferric iron and reduce) add 20 ml of the acid mixture and 3 to 4 drops of diphenylamine indicator and titrate against standard solution of potassium dichromate till the green colour changes to blue violet. vi) Repeat the titration for concurrent value and calculate the normality of iron solution. Result: Amount of Ferric iron present in the whole of the given solution (100 ml) = ______ gm. _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Preparation of Standard solution: W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2 ) = ____________ gms.
Normality of the solution (K 2Cr 2O7) = (W1-W2) X 10/Equivalent Weight= = (W1-W2) X 10/49=
S.No
Volume of the standard solution(V2)
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
Volume of consume (V1)
Final
V2 = 20 ml
N1 = Normality of K 2Cr 2O7 solution = N2 = Normality of Ferric iron solution =? V1 = Volume of K 2Cr 2O7 solution = V2 = Volume of Ferric iron solution = 20 ml N1 V1= N2 V2 N2 = N1 V1 / V2 Normality of Ferric iron solution = N2 = N1 V1/V2 Amount of Ferric iron present in the whole of the given solution (100 ml) = N2 X 55.85/10= Result: Amount of Ferric iron present in the whole of the given solution (100 ml) = ______gm.
Experiment-3 ESTIMATION OF COPPER (IODOMETRY) Aim: To estimate the amount of Copper present in the given solution using a standard solution of Potassium Dichromate and Hypo as the link solution. Apparatus: 100 ml standard flask, Funnel, Burette, Iodometric flask, Conical Flask, Pipette, Simple balance with weights Chemicals Required: K 2Cr 2O7, Hypo (Na2S2O3), KI, Conc.HCl, dil. Acetic acid, NaHCO3, H2SO4, CuSO4, Ammonia solution, Starch & distilled water. Principle:
Any cupric salt in neutral medium when treated with Potassium Iodide forms a white precipitate of cuprous iodide and iodine is set free quantitatively. The liberated Iodine is treated against Hypo using starch as the indicator.
Chemical reactions: CuSO4 + 2KI 2CuI2 I2 + 2Na2S2O3 +O2 2CuSO4 = I2 = Na2S2O3
CuI2 + K 2 SO4 Cu2I2 + I2 Na2S2O6 + 2NaI
Procedure: Preparation of standard potassium dichromate: i. Weigh out accurately the given pure crystalline crystalline sample of potassium dichromate and transfer into 100 ml standard (volumetric) flask provided with a funnel. ii. Dissolve the dichromate in a small quantity of distilled water, and make u p to the mark. iii. The contents in the flask are shaken well for uniform concentration. iv. Calculate the normality of potassium dichromate. 2. Standardization of sodium thiosulphate: i. Rinse the burette and fill it up with hypo solution without any air bubbles. ii. Note the burette reading. Take about 20 ml of 10%KI solution in a clean conical flask and add 2 grams of o f sodium bicarbonate followed by 5 ml of concentrate HCl gently rotate the flask for mixing the liquids. iii. Rinse the pipette with a little of potassium dichromate solution and then transfer 20 ml of the same to the conical flask. iv. Shake it well, stopper it, and keep it in dark place for 5 minutes. Titrate the liberate iodine by running down hypo from the burette with constant stirring. v. When the solution attains a pale yellow colour add 2 ml of freshly prepared starch solution. vi. The colour changes to blue. vii. Continue the titration drop-wise till the colour changes from blue to light green indicating the end point. viii) Repeat the titration for concurrent values. 1.
Estimation of copper: i. Make up the given solution of copper to 100 ml with distilled water and shake well for uniform concentration. ii. Pipette out 20 ml of this solution into a clean conical flask. iii. Add few drops of ammonia when bluish b luish white precipitate is obtained. iv. Redissolve the precipitate in dilute acetic acid. Now add 10 ml of 5% KI, when iodine is liberated giving a brown colour. v. Titrate this solution against standard hypo solution till light yellow colour is obtained. vi. Now add 2 ml of starch solution and continue the titration till blue colour changes to creamy white, which is the end point. vii. Repeat the titration for concurrent values and calculate the amount of copper. _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Preparation of Standard solution: 3.
W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2 ) = ____________ gms. Normality of the solution = (W1-W2) X 10/Equivalent Weight = = (W1-W2) X 10/49=
S.No
Volume of the standard K 2Cr 2O7 solution (V 1)
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
Volume of consume (V2)
Final
V1 =
V2 =
N1 = Normality of K 2Cr 2O7 solution = V1 = Volume of K 2Cr 2O7 solution = 20ml N2 = Normality of Hypo =? V2 = Volume of Hypo = N1 V1= N2 V2 N2 = N1 V1 / V2 N2 = Normality of Hypo =
S.No
Volume of the Copper solution (V 3)
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
Volume of consume (V4)
Final
V3 = 20ml
V4 =
N3 = Normality of the Copper solution =? V3 = Volume of the Copper solution = 20ml N4 = Normality of Hypo =? V4 = Volume of Hypo = N3 V3= N4 V4 Normality of the Copper solution = N3 = N4 V4 / V3 Amount of Copper present in the whole of the given solution (100 ml) = N3 X 63.54/10 who le of the given solution (100 ml) = ______ __ ____ gm. Result: Amount of Copper present in the whole
Experiment-4 ESTIMATION OF CALCIUM HARDNESS OF WATER (COMPLEXOMETRY) Aim: To estimate the Calcium hardness of the given solution using a standard solution of EDTA. Apparatus: 100 ml standard flask, Burette, 250 ml Conical Flask, 20 ml Pipette & Simple balance with weights. Chemicals Required: Ethylene di-amine tetra acetic acid (EDTA), Solochrome (EBT) Indicator, Ammonia Buffer solution, Hard-water & distilled water. Principle:
Hard water which contains calcium and magn esium ions forms a wine red colored complex with the indicator, Eriochrome Black-T. Ethylene diamine tetra acetic acid (EDTA) forms a colourless stable complex with free metal ion like Ca, Mg. i.e., Metal + Indicator Metal indicator complex (wine red colour) When EDTA is added from the burette, it extracts the metal ions from the metal ion-indicator complex thereby releasing the free indicator. (The stability of metal ion-indicator complex is less than that of the metal ion- EDTA co mplex, and hence EDTA extracts metal ion form the ionindicator complex.) EDTA + Metal indicator complex (wine red colour)
Metal ion-EDTA + Indicator (Blue)
The reactions take place at a pH = 10 and the buffer is made by ammonium chloride and ammonium solution. Procedure: 1.
Preparation of standard solution of EDTA: i. Weigh out accurately about 0.3722 gms of EDTA sample into a 100ml standard flask and dissolve in a minimum quantity of distilled water. ii. Make up the solution upto the mark with distilled water and shake the flask well for uniform concentration.
M1 = Molarity of the EDTA solution = Weight of EDTA transferred x 10 / 372.24 2.
Estimation of Calcium hardness of water:
i.
ii. iii. iv.
Make up the given solution of calcium upto the mark and shake the flask well for uniform concentration. Rinse the pipette with the calcium solution and pipette out 20 ml into a clean conical flask. Add 2 ml of buffer bu ffer followed by 1-2 ml of Eriochrome Black – T and titrate the solution till a clear blue colour persists. This marks the end point of the titration. Repeat the titrations for constant titer values and calculate the amount of calcium present in the whole of the given solution.
Result: The calcium hardness of the given water sample = _________ ppm. _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Preparation of Standard solution: W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2) = ____________ gms. Molarity of the solution = (W1-W2) X 10 / 372.24 =
S.No
Volume of the Copper solution (V 2)
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
V2 = 20ml
Calculations: M1 = Molarity of EDTA = V1 = volume of EDTA solution = M2 = Molarity of calium solution = ?
Volume of consume (V1)
Final
V1 =
V2 = Volume of Calcium solution = 20 ml M1V1 = M2V2 M2 = Molarity of calium solution = M1V1/V2 Calcium hardness of the given sample water = M2 X 100 X 1000 Calcium hardness of the given sample water = M2 X V1 X100 X 1000/V2
Result: The calcium hardness of the given water sample _________ ppm.
Experiment-5 ESTIMATION OF COPPER BY EDTA (COMPLEXOMETRY) Aim: To estimate the Copper in the given solution by preparing a standard solution of EDTA. Apparatus: 100 ml standard flask, Burette, 250 ml Conical Flask, 20 ml Pipette, Simple balance with weights, Chemicals Required: Ethylene di-amine tetra acetic acid (EDTA), Fast sulphone Black-F Indicator, Ammonia solution, Copper solution, Distilled water. Principle:
Fast sulphone Black-F indicator is specific in its reaction with copper in ammonia solution, it forms red complex with copper. In the titration of copper in ammonical solution the colour changes at the end point from pale blue to bright green depend upon the concentration of Cu++ ions. Procedure: Preparation of standard solution of EDTA: i. Weigh out accurately about 0.3722 gms of EDTA sample into a 100ml standard flask and dissolve in a minimum quantity of distilled water. ii. Make up the solution upto the mark with distilled water and shake the flask well for uniform concentration. 2. Estimation of Copper: 1.
i. ii. iii.
iv.
Makeup the given solution of copper upto the mark and shake the flask well for uniform concentration. Rinse the pipette with the copper solution and pipette out 20 ml of copper solution into a clean 250 ml conical flask. Add 20 ml of distilled water and 5 ml of ammonia solution and 5 drops of the fast sulphone black-F indicator solutions titrate with standard EDTA solution until the colour changes of from blue to a dark green. Repeat the titration to get the concurrent values.
Result: Amount of copper present in the given 100ml of solution =________ _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Preparation of Standard solution: W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2) = ____________ gms.
Molarity of the solution = (W1-W2) X 10/Molecular Weight =
S.No
Volume of the standard solution (V 2)
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
V2 = 20ml
Calculation: M1 = Molarity of EDTA = V1 = volume of EDTA solution = M2 = Molarity of copper solution = ? V2 = Volume of Copper solution = 20 ml
Volume of consume (V1)
Final
V1 =
M1V1 = M2V2 M2 = Molarity of copper solution = M1V1/V2 1 ml of 0.05 M EDTA = 3.177 mg of Cu2+ Amount of copper present in the given 100ml of solution = Titre value x Molarity of EDTA x 3.177 3 .177 x 1000/0.05 x 20 = Result: Amount of copper present in the given 100ml of solution =_______
Experiment-6 ESTIMATION OF FERROCYANIDE (PRECIPITATION TITRATIONS) Aim: To estimate the amount of Potassium Ferrocyanide in the given solution by preparing a standard solution of Zinc. Apparatus: 100 ml standard flask, Burette, 250 ml Conical Flask, 20 ml Pipette, 20 ml Measuring cylinder, Simple balance with weights. Chemicals Required: Zinc oxide (ZnO), Sulphuric acid (H2SO4), Potassium Ferrocyanide, Ammonium sulphate (NH4)2SO4, Biphenyl benzidine indicator, Distilled water. Principle:
Zinc ions in neutral or acid medium reacts with Potassium Ferrocyanide solution form sparingly soluble potassium zinc Ferro cyanide. 3Zn2+ + 2K 4 Fe(CN)6
K 2Zn3 Fe(CN)6 + 6K +
Biphenyl benzidine is used as indicator. At the end point the colour of the solution changes from Blue violet to pale green. Procedure: Preparation of Standard Zinc solution: i. Weigh out the given zinc oxide ox ide into a 100 ml standard flask, dissolve it in 10 ml of diluted sulphuric acid and make upto the mark with distilled water and shake the flask well for uniform concentration. 2. Standardisation of Potassium Ferrocyanide : i. Make up the given potassium po tassium Ferro-cynidesolution with distilled water and shake the flask well for uniform concentration. ii. Rinse the pipette zinc oxide solution and pipette out 20 ml of zinc solution into 250 ml conical flask; add 20 ml of distilled water, 20 ml of 7N H2SO4, and 8 grams of ammonium a mmonium sulphate and 3-4 drops of diphenyl benzidine indicator. iii. Titrate the solution slowly, with vigorous shaking against potassium ferro-cynide until the colour changes from blue violet to green. iv. Repeat the titration to get concurrent values. 1.
Result: Amount of Potassium Ferro-cyanide in the given solution = _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Preparation of Standard solution: W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2) = ____________ gms.
Molarity of the solution = (W1-W2) X 10/81.38 =
S.No
Volume of the standard solution (V 1)
1
20 ml
2
20 ml
3
20 ml V1 = 20ml
Bur ette Readi ng Initial
Volume of consume (V2)
Final
0 ml
V2 =
M1 = Molarity of Zinc oxide solution = V1 = volume of Zinc oxide solution = 20 ml M2 = Molarity of Potassium ferrocyanide solution = ? V2 = Volume of Potassium ferrocyanide solution = n1, n2 indicates number of molecules involved in the reaction n1= 3, n2= 2 Calculation:
M2 = Molarity of Potassium ferrocyanide solution = M1V1 n2/V2 n1 M2 = M1V1 n2/V2 n1 = M2 = Amount of Potassium ferrocyanide in the given solution = M2X 422.4/100
Result: Amount of Potassium ferro-cyanide in the given solution =________
Experiment-7 DETERMINATION OF PERCENTAGE PURITY OF PYROLUSITE (ANALYSIS OF MINERALS AND ORES) Aim: To estimate the amount of MnO2 present in the given sample and hence percentage purity of Pyrolusite. Apparatus: 100 ml standard flask, Burette, Conical Flask, 20 ml Pipette, Funnel,
Simple balance with weights, Heating equipment. Chemicals Required: Pyrolusite, 4N Sulphuric acid (H2SO4), Sodium oxalate solution, Potassium permanganate (KMnO4), Distilled water. Principle: The MnO2 present in the pyrolusite sample is reduced by a known excess of standard sodium oxalate in acid medium.
The unreacted sodium oxalate is titrated against a standard KMnO4, until pale pink coloured end point is obtained. MnO2 + H2SO4 + H2C2O4
2CO2 + 2H2O + MnSO4
Procedure: i.
ii. iii.
Weigh out accurately the given powdered pyrolusite sample into a clean dry conical flask and pipette out 40 ml of standard sodium oxalate solution and add 50 ml of 4N (H2SO4) sulphuric acid, put a small funnel into the mouth of the conical flask. Heat with small flame till particles are MnO2 disappear in the conical flask. Rinse the funnel with distilled water into the conical flask, titrate the hot solution, containing the unreacted sodium oxalate with standard KMnO4 solution till there is a pale pink colour.
Result: Percentage purity of the given sample of Pyrolusite =________ _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Preparation of Standard solution: W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2) = ____________ gms.
Normality of the solution = (W1-W2) X 10/Equivalent Weight = __________X 10/31.6. S.No
Volume of the standard solution
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
0 ml
Volume of consume (V)
Final
V =
Calculations:
Titer value = V = Blank = 1 ml of 1N KMnO4 = 1N Na2C2O2 = 0.04346 g of MnO2 Percentage of MnO2 = (Blank-titervalue) X Normality of KMnO4 X 0.04346 X 100/Weight of the sample
Note: Blank from the instructor i.e., 20 ml of oxalate equivalent to permanganate of certain normality.
Result: Percentage purity of the given sample of Pyrolusite =
Experiment-8 PERCENTAGE PURITY OF LIME-STONE (ANALYSIS OF MINERALS AND ORES) Aim: To determine percentage purity of the sample of Lime stone (estimation of Calcium). Apparatus: 500 ml Beaker, Stirrer, 100 ml standard flask, Burette, 250 ml Conical Flask,
Pipette, Funnel, Simple balance with weights, Heating equipment Distilled water & filter paper (No.40). Chemicals Required: Lime stone, Hydrochloric acid (HCl), Methyl red indicator, Sulphuric acid (H2SO4), 10% ammonium oxalate solution, Ammonium hydroxide, Potassium permanganate (KMnO4)& distilled water. Principle:
The given Lime stone sample is weighed out into a beaker and dissolved in HCl. The calcium present in the solution is precipitated as oxalate by the addition of ammonium oxalate in neutral medium and the precipitate is dissolved in dilute H2SO4 and the liberate oxalic acid is titrated with standard KMnO4 solution. CaC2O4+H2SO4 5 (H2C2O4) + 2KMnO4
CaSO4 + 3H2C2O4 2MnSO4+ 10CO2 + 8H2O
Procedure: i.
ii.
iii. iv. v.
vi. vii.
Weigh out accurately the given Lime stone sample into a 400 ml beaker, add 10 ml of distilled water, then add 10 ml of dilute Hydrochloric acid along the sides of the bea ker and completely dissolve the lime-stone sample. Add 4 to 5 drops of methyl red indicator, heat the solution to boiling add about 25 ml of 10% 1 0% solution of ammonium oxalate solution with constant stirring. To the hot solution add 1:1 Ammonium hydroxide drop wise with stirring until the solution is neutral (Red to Yellow). Allow the solution to stand for 30 minutes on water ba th. Test for complete precipitation and decant clear supernatant liquid through a Whatman No. 40 filter paper and quantitatively transfer the precipitate to the filter paper. Wash the precipitate on filter paper repeatedly until the washings are free from oxalate/chlorides. Transfer the precipitate present on the filter paper into a 400 ml beaker, add 25 to 30 ml dilute suphuric acid, warm the solution and titrate with standard permanganate solution to a pale pink colour end point.
Result: Amount of calcium present in the sample =
Percentage purity of the given sample of Limestone = %
___________________________ ___________________________________________ _______________________________________________________ _______________ _____ Preparation of Standard solution: W1 = Weight of bottle + substance = ____________ gms W2 = Weight of bottle = ____________ gms Weight of substance = (W1-W2) = ____________ gms. Normality of the solution = (W1-W2) X 10 / Equivalent Weight = __________X 10/31.6.
S.No
Volume of the standard solution
1
20 ml
2
20 ml
3
20 ml
Bur ette Readi ng Initial
Volume of consume (V)
Final
0 ml
V =
Calculations:
Titer value = V = 1 ml of KMnO4 = 0.200 g of Ca. Amount of calcium present in the sample = Titer value (V) X Normality KMnO4 X 0.2004 =
% Purity of Lime stone = Amount of Calcium X 100/Weight of the sample =
Result: Amount of calcium present in the sample = Percentage purity of the given sample of Limestone = %
Experiment-9 ESTIMATION OF MANGANESE IN STEEL (Colorimetric Estimation) Aim: To estimate the percentage of Manganese present in a sample of mild steel calorimetrically. Apparatus: 100 ml standard flask, 250 ml Conical Flask, 20 ml Pipette, 10 ml Measuring cylinder, Funnel, Simple balance with weights, Heating equipment Colori-meter & centrifuge apparatus. Chemicals Required: Steel sample, Nitric acid (HNO3), Syrupy phosphoric acid(H3PO4), Lead peroxide & distilled water. Principle:
The given steel sample is dissolved dissolved in nitric nitric acid. Manganese (II) (II) is oxidized to permanganic acid by heating with lead peroxide and conc. Nitric acid. The intensity of the permanganic acid is measured in the colorimeter and the amount of manganese is estimated. Procedure: 1.
Dissolution of the steel sample: i.
ii. iii. iv.
2.
Weight out about 0.5 grams (500 mg) of the given steel sample into a clean 250 ml conical flask and add about 30 ml of 1:3 nitric acid heat to boiling, till the sample goes into solution. Boil gently for about 10 to 15 minutes, to oxidize any carbon present, cool and transfer into a clean 100 ml standard flask. Wash the conical flask twice with about 10 ml portions of distilled water and transfer into the standard flask. Make up the solution upto the mark with distilled water and shake well for uniform concentration.
Development of Colour: i. Transfer 20 ml of the prepared solution into a clean conical flask add about 10ml of syrupy phosphoric acid and about 20 ml of 1:3 nitric acid and heat the solution to boiling. ii. Add two spatulas of lead peroxide and continue the boiling for about 5 minutes. iii. Take out the flask from the stand and allow it to cool and settle.
iv.
v.
vi.
Decant the supernatant liquid into a 100 ml standard flask, wash the precipitate twice with little distilled water and collect the supernatant liquid and the washings into the standard flask and make up the solution with distilled water and shake well uniform concentration. Transfer about 10 ml of the solution into a clean centrifuge tube and centrifuge the solution to separate out any lead peroxide particles. Measure the optical density in the colorimeter and calculate the amount of Manganese from the standard calibration curve.
Result: Percentage of Manganese present in the mild steel sample is = _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Weight of the sample: W1 = Weight of bottle + sample = ____________ ____ ________ gms W2 = Weight of bottle = ____________ gms Weight of sample = (W1-W2) = ____________ gms. = ____________ mgs Standard value for calibration curve
Amount of Manganese (in mg) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
X = Optical density of the solution = Y = Corresponding value of Mn from the curve =
O. D 0.035 0.065 0.100 0.130 0.155 0.190 0.220 0.245 0.260
Calculations:
Percentage of Manganese present in the steel sample = Y x 100 x 100/20 x (W1-W2) mg Result: Percentage of Manganese present in the mild steel sample is = _______.
Experiment-10 ESTIMATION OF FERRIC IRON IN CEMENT (Colorometric Estimation) Aim: To estimate the amount of Iron (Ferric) present in a sample of cement by calorimetrically using ammonium thiocyanate as a reagent. Apparatus: 250 ml beaker, Glass rod, Watch glass, 100 ml standard flask, Burette, 10 ml Pipette, Simple balance with weights Colori-meter, Heating equipment. Chemicals Required: Cement sample, Conc. Nitric acid (HNO3), Hydrochloric acid (HCl) Ammonium thio-cyanate & Distilled-water. Principle:
Ammonium thio-cyanate yields a blood red colour with ferric iron and the colour produced is stable in nitric acid medium. Its optical density is measured in a photo colorimeter and the concentration c oncentration of ferric iron is found from a standard calibration curve.
Procedure: 1.
Dissolution of the sample : i.
Weight out accurately about 0.1 gram of the cement sample into a clean 250 ml beaker add about 5 ml of water to moisten the sample.
ii. iii. iv.
2.
Place a glass rod and cover the beaker with a watch glass add about 5 ml conc. Hydrochloric acid (HCl) dropwise and heat the solution till the sample dissolved. Keep the beaker on a small flame and evaporate the solution to almost dryness to expel the excess acid.
Development of Colour: i. ii. iii. iv.
Pipette out 10 ml of the solution prepared above, into a 100 ml standard flask, add 1 ml of conc. Nitric acid (HNO3) from a burette and 5 ml of 40% ammonium thiocyanate from a burette. Make up the solution to 100 ml with distilled water and shake the flask well for uniform concentration. Find out the optical density of the solution using the photo colorimeter and the concentration of the ferric iron from the calibration curve.
ce ment sample = Result: Percentage of Ferric iron present in the cement _______________________________________________________ ___________________________ ___________________________________________ _______________ _____ Weight of the sample: W1 = Weight of bottle + sample = ____________ ____ ________ gms W2 = Weight of bottle = ____________ gms Weight of sample = (W1-W2) = ____________ gms. Standard value for calibration curve
Concentration in Milligrams 0.5 0.10 0.15 0.20 0.25 0.30 0.35 0.40
O. D 0.11 0.22 0.32 0.40 0.50 0.62 0.70 0.80
X = corresponding amount of from the calibration curve =
Calculation:
Percentage of Fe3+ present in the given cement sample = X x 10 x 100 / (W1 – W2) mg
ce ment sample = Result: Percentage of Ferric iron present in the cement
ENGINEERING CHEMISTRY LAB I B.TECH CIVIL ENGINEERING
Viva-voce questions Experiment-1 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. Which type of titration involved in this experiment? 8. Name the chemicals of in this experiment? exp eriment? 9. What is the molecular weight of potassium dichromate? 10. What is the molecular weight of ferrous ammonium sulphate? 11. Name the apparatus used this experiment?
Experiment-2 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. Which type of titration involved in this experiment? 8. Name the chemicals of in this experiment? exp eriment?
9. What is the molecular weight of potassium dichromate? 10. What is the molecular weight of ferric ammonium sulphate? 11. Name the apparatus used this experiment?
Experiment-3 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. What is the chemical formula of Hypo? 8. Which type of titration involved in this experiment? 9. Name the chemicals of in this experiment? exp eriment? 10. What is the molecular weight of potassium dichromate? 11. What is the molecular weight of Hypo? 12. Name the apparatus used this experiment?
Experiment-4 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. Which type of titration involved in this experiment? 8. Name the chemicals of in this experiment? exp eriment? 9. What is the molecular weight of EDTA? 10. Name the apparatus used this experiment?
Experiment-5 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. Which type of titration involved in this experiment? 8. Name the chemicals of in this experiment? exp eriment? 9. What is the molecular weight of EDTA? 10. Name the apparatus used this experiment?
Experiment-6 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. Which type of titration involved in this experiment? 8. Name the chemicals of in this experiment? exp eriment?
9. What is the molecular weight of zinc oxide? 10. Name the apparatus used this experiment?
Experiment-7 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. In this experiment do-not required any indicator, why? 8. Name the chemicals of in this experiment? exp eriment? 9. 1 ml of 1N KMnO4 is equal to how much amount of MnO2? 10. What is the molecular weight of MnO2? 11. Name the apparatus used this experiment?
Experiment-8 1. Define normality? 2. Define molarity? 3. How to prepare standard solution? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator used in this experiment? 7. 1 ml of KMnO4 is equal to how many grams of calcium? 8. Name the chemicals of in this experiment? exp eriment? 9. What is the molecular weight of potassium permanganate? 10. Name the apparatus used this experiment?
Experiment-9 1. Define normality? 2. Define molarity? 3. Name the chemicals of in this experiment? exp eriment? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator/reagent used in this experiment? 7. Which type of estimation involved in this exp eriment? 8. Define concentration of the solution? 9. Name the apparatus used this experiment? exp eriment?
Experiment-10 1. Define normality? 2. Define molarity 3. Name the chemicals of in this experiment? exp eriment? 4. To explain the principle of this experiment. 5. To explain the difference between molarity & normality/ 6. Which indicator/reagent used in this experiment? 7. Which type of estimation involved in this exp eriment? 8. Define concentration of the solution? 9. Name the apparatus used this experiment? exp eriment?
