log Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 01

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1 Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 01 Name: Redox Titration (Estimation of Iron Using Permanganometry Theory: In a chemical reaction, if one substance is oxidized the other is reduced. In other ords, oxidation and reduction occurs simultaneously. Oxidation is defined as the process of one or more electrons and reduction is the gain of electron or electrons by atoms or ions. The reagents undergoing reduction is called oxidizing agent (oxidant), the reagent hich undergoes oxidation is called reducing agent (reductant). In a redox titration, a reducing agent is titrated against an oxidizing agent or vice-versa. In this titration, potassium permanganate is the commonly used oxidizing agent hich is titrated against a reducing agent like ferrous ammonium sulfate. Potassium permanganate oxidizes ferrous ion into ferric ion in acid medium in cold for its higher standard reduction potential and is itself reduced to colorless manganous ion. But ith decrease in H + conc. i.e. increase in ph of the medium, the potential falls and the oxidizing poer decreases. MnO H + +5e - Mn +2 +4H 2 O E 0 = 1.51V 5Fe +2 5Fe +3 +5e - E 0 = 0.77V MnO Fe +2 +8H + Mn +2 +5Fe +3 +4H 2 O Cl 2 + 2e 2Cl - E 0 = 1.36V Permanganate also oxidises Cl - present in the medium to Cl 2. So excess MnO 4 - is consumed. To prevent this the titration is carried out in prsence of Zimmermann- Reinhardt (Z.R)solution consisting of MnSO 4, H 3 PO 4 and H 2 SO 4. Function of MnSO 4 : It supplies excess of Mn +2 ; as a result the formal potential of MnO 4 - /Mn +2 system falls belo 1.36V ; consequently MnO 4 - can no longer oxidise Cl - to Cl 2. E = log Function of H 3 PO 4 : It removes yello Fe +3 by forming colourless soluble complex ion, [Fe(HPO4)] + ;as a result (i) the standard reduction potential of Fe +3 / Fe +2 system decreases and the formal potential falls belo 0.77V to permit quantitative oxidation of Fe +2 by MnO 4, (ii) sharp detection of the end point becomes possible. Function of H 2 SO 4 : It maintains the proper acidity of the solution and thereby prevents the precipitation of Manganese phosphate in the Z.R. solution. Apparatus:

2 1. Burette 2. Pipette 3. Conical flask 4. Volumetric flask 5. Measuring cylinder 6. Beakers Materials Required: 1. Dilute sulfuric acid 2. Ferrous ammonium sulfate solution [ (NH 4 ) 2 SO 4. FeSO 4. 6H 2 O ] 3. Given KMnO 4 solution 4. Zimmermann Reinhardt solution ( MnSO 4 + conc. H 2 SO 4 + H 3 PO 4 ) 5. Distilled ater Procedures: (1) Preparation of standard oxalic acid solution Equivalent eight of oxalic acid is 63. Hence in order to prepare 250 ml of (N/10) solution, gm oxalic acid is required. Weight out gm of AR quality oxalic acid into a clean 250 ml volumetric flask. Wash the entire quantity of solid into the flask by careful addition of distilled ater. Hold the flask firmly and shake carefully. When the entire solid has dissolved, makeup the volume to the mark. Let the eight of oxalic acid taken = gm of oxalic acid = (N/10) Table 1: Weighing of oxalic acid Initial eight(gm) Final eight(gm) Weight taken(gm) Weight to be taken(gm) W 1 W 2 W 1 -W 2 = (2) Determination of strength of given KMnO 4 solution Take 5 ml of oxalic acid solution in a conical flask. Add 30 ml of 2(N) H 2 SO 4.Heat to about 80 0 C. Run in the permanganate solution, ith constant stirring and see that the temperature of the solution may not fall belo 60 0 C during titration. Stop addition of KMnO 4 solution hen just one drop imparts pink colour to the hole mass of the solution. Note that the pink colour after lasting for 30 seconds may disappear again. Note the volume of KMno 4 solution added. Repeat the titration tice at least. Table 2: Determination of strength of KMnO 4 solution

3 No. of observation oxalic acid (ml) Burette reading of KMnO4 solution (ml) Initial Final KMnO 4 (ml) of oxalic acid of KMnO 4 (2) Standardization of Ferrous ammonium sulfate against KMnO 4 solution: Take 5 ml of ferrous ammonium sulfate solution in a conical flask. Add about to 2.5 ml of Zimmermann Reinhardt mixture. Dilute to 50 ml ith distilled ater. Run the permanganate solution from the burette till a faint pink colour develops through the hole mass of the solution Table 3: Standardization of ferrous ammonium sulfate No. of observation ferrous ammonium sulfate solution (ml) Burette reading of KMnO4 solution(ml) Initial Final KMnO 4 (ml) of KMnO 4 Iron present per litre(gm) Calculation:

4 Let the exact strength of KMnO4 solution as determined by experiment = S (N) The volume of KMnO 4 solution required to oxidize 5 ml 0f ferrous iron solution = V ml Since 1000 ml of 1(N) KMnO4 solution = 56 gm of iron 1 ml of 1(N) KMnO4 solution =0.056 gm of iron V ml of S (N) KMnO4 solution = (0.056 S V) gm of iron 5 ml of ferrous iron solution contain (0.056 S V) gm of iron 1000 ml of ferrous iron solution contain (0.056 S V 200) gm of iron Precautions: Titration is carried out at room temperature. All the apparatus should be ashed ith distilled ater before use. Rinse the burette ith a solution of KMnO 4 to be taken in the burette. Rinse the pipette ith a solution to be taken in the conical flask. Wash the conical flask ith distilled after every titration.

5 Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 02 Name: Complexometric Titration (Estimation of Calcium and Magnesium Hardness separately using EDTA Titration) Theory: Complexometry involves the estimation of metal ions titrimetrically through complex formation ith a strong multidentate chelating ligand. Ligands having more than one co-ordinate centres are knon as chelating ligands. They give extra stability to a metal complex due to chelate effect-the stability increases ith the number of points. They give extra stability to a metal complex due to chelate effect-the stability increases ith the number of points of attachments of the ligand to a metal ion. In this titration, Ethylene diamine tetra-acetic acid(edta) is used as a chelating ligand. The total hardness of ater is due to dissolved calcium salts and magnesium salts and expressed as part of CaCO 3 equivalent per million part of ater(ppm). The total hardness is conveniently determined by resin, i. e.,disodium hydro ethylene diamine tetra acetate dehydrate Na 2 H 2 C 10 H 12 O 8 N 2,2H 2 O(m.t.=372.25)generally formulated as Na 2 H 2 Y,2H 2 O, using Erichrome black T indicator(ebt). HOOCH 2 C + Na OOCH 2 C N CH 2 CH 2 N EDTA Salt CH 2 COO Na + CH 2 COOH Beteen ph 7 to 11, Erichrome black T is blue colour. Addition of metallic salt produces in this stage a brilliant change in color from blue to ine red.

6 EBT(Blue) M M = Ca or Mg NO 2 SO 3 - Na+ N= N O O M EBT Metal complex (Wine red) When the ine red complex is treated ith the disodium salt of EDTA, the complex is formed rapidly; the ine red becomes blue, due to the formation of indicator itself, along ith hich is colorless According to the equation. M In + Na(HEDTA) = Na 2 (MEDTA) + In H 2 Colorless Blue The hardness of ater due to dissolved calcium salts is conveniently determined by using also dihydrate salt of disodium hydro ethylene diamine tetra acetate generally formulated as Na2H2Y,2H2O ith murexide as an another metal indicator ( its original color is purple or red violet). Murexide, ammonium salt of purpuric acid is another metal indicator hich complex ith only Ca +2 ions present in the hard ater and the color of the solution becomes pink. O NH NH O O N O NH N O NH4 + O M M= Ca O NH NH O O N Ca + O O NH N O Purple Pink When the pink complex is treated ith the disodium salt of EDTA, the M-EDTA complex is formed rapidly ; so the pink color becomes purple due to the formation of indicator itself hich is purple in color.

7 M In + Na(HEDTA) = Na 2 (MEDTA) + In H 2 Colorless Purple Chemicals Required: 0.01(M) EDTA solution Buffer of ph = 10 (Mixture of NH 4 Cl and NH 4 OH ) EBT indicator 2(N) NaOH solution Murexide indicator Apparatus: Burette Pipette Conical flask Beaker Procedure: 1. Determination of Total hardness of ater by EDTA solution: Take 25 ml of the given ater sample in a clean conical flask. To this add 1 ml buffer solution of ph = 10 and then add 2 drops of EBT indicator. Then titrate against EDTA solution from burette until the color changes from ine red to blue ith 1 drop of EDTA solution. Table 1: Determination of Total Hardness of ater by EDTA solution No.of observation ater sample taken(ml) Burette reading of EDTA Initial(ml) Final(ml) EDTA(ml) Total hardness in ppm

8 2. Determination of Calcium hardness of ater by EDTA solution: Take 25 ml of sample ater in a conical flask. To this add 1 ml of 2(N) NaOH solution and then add 1 drop of murexide indictor. Then titrate against EDTA solution from burette until the color changes from pink to purple ith 1 drop of EDTA solution. Table 2: Determination of calcium hardness of ater by EDTA solution: No.of observation ater sample taken(ml) Burette reading of EDTA Initial(ml) Final(ml) EDTA(ml) Calcium hardness in ppm Calculation: Let the burette reading of EDTA = V ml 1000 ml of 1(M) EDTA = 1000 ml of 1(N) CaCO 3 = 100 gm of CaCO 3 1 ml of 1(M) EDTA =10-1 gm of CaCO3 V ml of 0.01(M) EDTA = 10-1 V 0.01 gm of CaCO 3 = V 10-3 gm of CaCO 3 Hence, 25 ml sample ater contain V 10-3 gm of CaCO 3 Therefore, V ml sample ater contain gm of CaCO 3 25 Precautions: Use distilled ater for ashing and rinsing of glass apparatus. Prepare EDTA solution in double distilled ater. Add same amount of indicator in each time. Maintain ph=10 during the titration by adding buffer. Correctly observe the end point.

9 Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 03 Name: Determination of percentage composition of sugar solution from viscosity Theory: Due to internal friction hen a fluid passes through one another, it experiences a resistance to its flo hich is knon as viscosity. The coefficient of viscosity is a measure of the

10 resistance and defined as the tangential force per unit area required to maintain unit difference of velocity beteen to layers unit distance apart. Its unit in CGS system is dyne.sec/cm 2. When a homogeneous fluid of volume v flos through a capillary tube of length l, radius r, in time t, under a driving force p, the co-efficient of viscosity is given according to Poisseuille s formula by 4 Pr t 8lv The experimental determination of viscosity is rather different. If 1 and 2 are the viscosity of to different liquids of density 1 and 2 respectively hich are successively alloed to fall through the same length h of capillary e.g. beteen the marks of an Ostald viscometer, the pressures are given by h 1 g and h 2 g and thus and 1 2 are given by 1= and 2 = P = Pressure difference beteen to ends. 1 1t 1 1t1, or t2 1t2 here x is the unknon concentration of supplied sugar solution. Apparatus: Viscometer (Ostald) Stop atch Stand ith clamp Pipettes Beakers

11 Specific gravity bottle Materials: Supplied sugar solution Distilled ater Procedure: The eight of dry specific gravity bottle, filled ith ater and ith supplied solution as taken. At first 5%, 10%, 15% and unknon sugar solution ere prepared by proper dilution. The density of the solution as determined. The viscometer as cleaned thoroughly a clamped vertically. Then a fixed amount of sugar solution as taken in it by sucking up and alloed to fall freely beteen the to marks and time as noted and repeated for three times. For 5%, 10%, 15% and unknon solution the same as repeated. Experimental Data: o Measurement of relative density of a solution Room temperature= C Density of ater at that temperature = gm/ cc Viscosity of ater at that temperature = Poise Wt. of dry and clean sp. Gravity bottle (gm) Wt. of sp. Gravity bottle ith ater (gm) Wt. of ater (gm) Wt. of sp. Gravity bottle ith solutions (gm) Wt. of solutions (gm) W 1 W 2 W 2 - W 1 = W W 3 W 3 -W 1 = W s 2. Density of sugar solution at different concentrations Concentration 5% 10% 15% Unknon solution Density (gm/cc)

12 3. Calculation of relative density: Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity usually means relative density ith respect to ater. It is unitless. Density = v m, here m = mass of liquid V = volume of liquid s Therefore relative density of solution = here s = density of sugar solution = m v m v As v is same for both liquid, therefore s = 4. Determination of Viscosity co-efficient s here ms m = density of ater m s = mass or eight of sugar solution m = mass or eight of ater v = volume of specific gravity bottle Substance No. of observation Time required (sec.) Mean time (sec) Density (gm/cc) Viscosity (Poise) Pure ater % solution % solution % solution 1 Unknon solution Calculation of viscosity of sugar solution:

13 s = st s t Therefore, s = t s t s here s = viscosity of sugar solution = viscosity of ater = density of sugar solution s = density of ater s t = time required for sugar solution t = time required for ater Precautions: The viscometer must be cleaned and rinsed. The viscometer should be clamp in a vertical position and its height must remain constant each time hen it is clamped. Exactly same volume of the to liquids should be used. The viscometer should not be disturbed during measurement of time of flo. Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 04 Name: Determination of Partition Co-efficient of Acetic Acid beteen Water and n-butanol Theory: The Nerst distribution la states that at constant temperature, hen different quantities of a solute are alloed to distribute beteen to immiscible solvents I contact ith each other, then at equilibrium the ratio of the concentration of the solute in to solvent layers is constant. When a solute is shaken in to immiscible liquids, then the solute is found to be distributed beteen the liquids in a definite manner, if the solute is soluble in each of the solvent. According C1 to distribution la, the distribution co-efficient at a particular temperature is given by K C 2 here C 1 and C 2 represents the concentration of solute in solvent 1 and 2 respectively, hen in solution phase solute molecules are in same state of association. No, if ater and n-butanol are taken as the pair of to immiscible solvents and acetic acid as the solute then as acetic acid retains its normal molecular eight in both the solvents, so the expression for partition co-efficient ill be

14 K = Apparatus: Stoppered bottles Volumetric flask Conical flask Burette Pipette Materials Required: Standard oxalic acid NaOH solution Acetic acid N-Butanol Distilled ater Phenolphthalein indicator Procedure: 1. A standard oxalic acid solution of (N/10) as prepared and NaOH solution as standardized against standard oxalic acid solution using phenolphthalein indicator. 2. In bottle 1, 20 ml acetic acid, 490 ml ater and 490 ml n-butanol as added. Similarly in bottle 2, 40 ml acetic acid, 480 ml ater and 480 ml n-butanol as added. 3. Stoppered bottles ere shaken for one hour and alloed to stand till the to liquid layers separated. 4. Definite volume of aqueous layer and organic layer from each of the to bottles ere taken out and standardized against NaOH solution Using Phenolphthalein as indicator. Experimental Results: Table 1: Composition of materials in each bottle Bottle 1 Bottle 2 20 ml acetic acid 40 ml acetic acid 490 ml ater 480 ml ater 490 ml n-butanol 480 ml n-butanol Table 2: Preparation of standard oxalic acid solution

15 Initial eight(gm) Final eight(gm) Weight taken(gm) Weight to be taken(gm) (N/10) W 1 W 2 W 1 -W 2 = Table 3: Standardization of NaOH solution by standard oxalic acid solution No. of observation oxalic acid (ml) Burette reading Initial(ml) Final(ml) NaOH (ml) of oxalic acid of NaOH solution Table 4: Standardization acetic acid in aqueous layer and n-butanol layer by NaOH solution Bottle No 1 2 Layer taken Organic layer Aqueous layer Organic layer Aqueous layer layer(ml) Burette reading of NaOH Initial(ml) Final(ml) required NaOH solution(ml) of acetic acid in layer Table 5: Determination of partition co-efficient Bottle No partition co-efficient Mean 1

16 2 Partition co-efficient of acetic acid = Calculation: V 1 S 1 = V 2 S 2 here V 1 = volume of NaOH S 1 = strength of NaOH V 2 = volume of acetic acid in layer S 2 = strength of acetic acid in layer Therefore, partition co-efficient, K= Precaution: During ithdraing aliquot one layer must not be contaminated ith the other. Pipette hich is used during the experiment must be cleaned. Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 05 Name: Conductometric Titration for determination of the strength of a given HCl solution by titration against a standard NaOH solution. Theory: The monobasic acid HCl being a strong electrolyte undergoes complete ionization and produces a large number of cations and anions in solution. Moreover ionic conductance of H + ions being highest (I 0 H+ = 350). Thus the initial conductance of a solution ill be very high. When this acid is gradually titrated against a base NaOH, being added from burette, the folloing reaction ill occur. H + + Cl - + Na + + OH - Na + + Cl - + H 2 O The salt, a strong electrolyte remains in the solution in completely ionized form, hile ater 9 being a very eak electrolyte ( 10 and in presence of H + ions its ionization is still smaller) remains partially ionized.

17 Thereby H+ ions are gradually replaced by equivalent amount of Na + ions hich have relatively much loer ionic conductance than that of H + ions. Thus the conductance of resulting solution ill decrease steeply. This trend ill continue until all the H + ions are replaced by Na + ions i.e. equivalent point is reached. At equivalent point only NaCl is present. Beyond equivalent point hen further amount of alkali is added Na + and OH - of excess alkali remain in the solution unutilized. Consequently the conductance of the solution increases due to the presence of nely added Na + and OH - ions (I o OH - = 200). The point of intersection of curve representing the variation of conductance ith the volume of alkali added, corresponding to the minimum conductance and consequently equivalence point. The volume of alkali added corresponding to the equivalent point represents the volume of alkali required for neutralization of acid. Instruments and apparatus: Conductivity meter Conductivity cell Beaker Burette Pipette Volumetric flask Conical flask Funnel Materials: Standard oxalic acid N NaOH solution 2 N HCl solution 10 N 10

18 Phenolphthalein indicator Procedure: N 1. Prepare 100 ml of standard oxalic acid order 10. N 2. Prepare 250 ml of an approximately NaOH solution and standardize it against oxalic 2 acid solution using phenolphthalein as indicator. N 3. Prepare 250 ml of an approximately HCl solution Rinse the conductivity cell ith de-ionized ater. 5. Pipette out 25 ml of HCl solution into the conductivity cell and add ater if necessary, so that both the electrodes are completely immersed ithin the solution. Join the cell ith the conductive bridge and measure the conductivity very carefully. 6. Add NaOH solution from a burette dropise. 7. Measure the conductance of the solution after addition of 10 drops of NaOH and mildly shaking the beaker. Repeat the process until you have at least six points beyond the end points. 8. Dra a curve by plotting the conductance against the drops of alkali added, find the end point and calculate the strength of the HCl solution. Results: Table 1: Weighing of oxalic acid Initial eight(gm) Final eight(gm) Weight taken(gm) Weight to be taken(gm) (N/10) W 1 W 2 W 1 -W 2 = Table2: Standardization of NaOH solution by standard oxalic acid No. of observation oxalic acid (ml) Burette reading of NaOH Initial(ml) Final(ml) NaOH (ml) of oxalic acid of NaOH Table 3: Conductometric Titration of HCl solution against NaOH solution. No of observation HCl taken (ml) Drops of NaOH added Conductance

19 Calculations: Let the number of drops of alkali required to neutralized 25 ml of HCl solution = x Therefore, 20 drops = 1 ml x x drops = ml 20 V 1 S 1 = V 2 S 2 here, V 1 = HCl S 1 = of HCl V 2 = NaOH S 2 = of NaOH VS 2 2 Then, S1 V 1 Precautions: Conductivity cell must be thoroughly ashed ith de-ionized ater. Ensure that there are no air bubbles in the burette. During titration, the beaker should be constantly sirled. For each titration, use same number of drops of NaOH solution.

20 Haldia Institute of Technology Engineering Chemistry Laboratory(CH 191 &CH 291) Experiment No.: 06 Name: ph-metric titration for determination of strength of a given HCl solution against a standard NaOH solution Theory: All ph meters have provision for standardizing the glass electrode in a buffer solution of knon ph.this is necessary because different electrodes have different asymmetry potentials. Once the adjustment has been made so that the meter Registers correctly knon the ph of the buffer solution, the instrument gives the ph other solution ithout any calculation. Measurements of ph are also employed to monitor the course of acid-base titrations. The ph values of the solution at different stages of acid-base neutralization are determined and are plotted against volume of acid/alkali added. On adding abase to an acid, the ph rises sloly in 1 the initial stages ph log (ph range is used for only dilute solution, not for concentrated H solution) and then it changes rapidly at the end point. Then it flattens out. The end point of the titration can be detected here the ph changes most rapidly. Hoever the shape of the inflexion point (i.e. here the ph changes abruptly) and symmetry of the curve on its to sides depends upon the ionisability of the acid and the base used and on the basicity of the acid and the acidity of the base.

21 Apparatus: ph meter ith glass electrode and standard calomel electrode. Beaker Burette Pipette Materials: Buffer solution of ph 4 and 9 N Standard oxalic acid 10 HCl solution NaOH solution Phenolphthalein indicator Procedure: 1. Wash the electrodes ith distilled ater and standardize the ph meter by using buffer solution of ph =4 and ph=9, no the selector sitch is put to a ph range of N 2. Prepare 100 ml of standard oxalic acid order Prepare 250 ml of an approximately NaOH solution and standardize it against oxalic acid solution using phenolphthalein as indicator. N 4. Prepare 250 ml of an approximately HCl solution Clean the electrodes by distilled ater and ipe them ith tissue paper. 6. Take 25 ml HCl solution in a 100 ml beaker and immerse the electrodes. 7. Add NaOH solution from the burette dropise. Note the corresponding value from the meter. Near the end point add very small amount of NaOH as possible because change in ph ill be very much appreciable because hen the acid is neutralized, further addition of such a small amount raises the ph to about 9 or 10.

22 8. Put back the selector to zero position after ph measurement and before removing the electrodes from solution 9. Plot a graph beteen ph and drops of NaOH added. From this graph, determine the volume of NaOH required for the complete neutralization of HCl. Experimental Data: Initial eight(gm) Table 1: Weighing of oxalic acid Final eight(gm) Weight taken(gm) Weight to be taken(gm) (N/10) W 1 W 2 W 1 -W 2 = Table2: Standardization of NaOH solution by standard oxalic acid No. of observation oxalic acid (ml) Burette reading 0f NaOH Initial(ml) Final(ml) NaOH (ml) of oxalic acid of NaOH Table 3: ph-metric titration of HCl solution against NaOH solution. No of observation HCl taken (ml) Drops of NaOH added ph 25 Calculation:

23 Let the number of drops of alkali required to neutralized 25 ml of HCl solution = x Therefore, 20 drops = 1 ml x x drops = ml 20 V 1 S 1 = V 2 S 2 here, V 1 = HCl S 1 = of HCl V 2 = NaOH S 2 = of NaOH VS 2 2 Then, S1 V Precautions: 1 Electrodes must be immersed properly in the solution and sufficient time to be alloed for the electrodes to assume the temperature of the solution. For ph-metric titration, solution should be stirred mechanically from time to time Leave the selector in zero position hen not in use. Primary knoledge about Chemistry practical: Standard solution: A solution of knon strength i.e. a solution hich contains a knon eight of a solute in a definite volume of solvent is called a standard solution. The strength(concentration) of a standard solution is usually expressed in Normality(N), Molarity(M) or Formality(F). To types of standard solutions are used. 1. Primary standard solution: Substances used for preparing such a standard solution should be (a) available in pure crystalline form (b) inert to atmosphere (not hygroscopic, not oxidized by air, no reaction ith CO 2 ) (c) of high equivalent eight, so that the eighing error is negligible (d) dried easily at C (e) of ready solubility of solvents like ater and the solution should be stable and its reaction should be instantaneous. Na 2 CO 3, H 2 C 2 O 4.2H 2 O, Na 2 C 2 O 4 ( sodium oxalate), K 2 Cr 2 O 7. NaCl, KCl, ZnCl 2 are used as primary standard solution. 2. Secondary standard solution: Water soluble impure (crystalline) substances of high equivalent eight and of instantaneous reactivity ith others, but strength of the solution of hich changes ith time, are used to be prepare secondary standard solution. HCl, H 2 SO 4, KOH, NaOH, KMnO 4, EDTA are commonly used as secondary standard solution. Gram-Equivalent eight: Gram-Equivalent eights of different substances are determined using the folloing formulas: Gram-Equivalent eight of Acid =

24 Gram-Equivalent eight of Base = Gram-Equivalent eight of Salt = Gram-Equivalent eight of oxidant = Gram-Equivalent eight of reducdant = Normality: Normality of the solution is the no. of gram-equivalent of the solute present in 1000 ml or 1 lt of the solution. Normality of solution is temperature dependent because although mass of solute is temperature independent, the volume of the solution depends on temperature. Molarity: The molarity of the solution is the gram-molecule of solute dissolved in 1 litre of the solution. Molarity of the solution is temperature dependent because although the mass of the solute is independent of temperature, the volume of the solution changes ith temperature. Formality: The formality of the solution is the no. of gram-formula eight of the solute present in 1 liter of the solution. The highly electrolyte compounds like NaCl, KCl, CaCl2 etc. hen dissolved in ater, ionize to form cations and anions. As in the aqueous solutions of ionic compound, there is no existence of any molecule or molecular entity, so in these cases, in expressing the strength of the solution, the unit of formality, is used instead of molarity. Molality: Molality denotes the no. of gram-molecule or mole of the solute dissolved 1000gm of the solvent. Acid-base indicator: Organic eak acids or bases, hich can indicate the end point of an acid-base titration by change of their on colour, are called acid-base indicator. They sho different colors in acid and alkaline medium. Ex: Phenolphthalein colorless in acid but pink in alkali. Buffer: A buffer solution means a solution, the ph of hich does not practically change on addition of small amounts of acid or alkalies.

25 The buffer solution generally consists of a mixture of eak acid and one of its salt in solution (e.g. acetic acid and sodium acetate) or a mixture of eak base and one of its salt solution (e.g. ammonium hydroxide and ammonium chloride) Haldia Institute of Technology Engineering Chemistry Laboratory (CH 191 &CH 291) Expt. No Name of Experiment 1 Redox Titration (Estimation of Iron Using Permanganometry) 2 To determine Calcium and Magnesium hardness of a given ater sample separately.

26 3 Viscosity of solutions (Determination of percentage composition of sugar solution from viscosity) 4 Heterogeneous equilibrium (Determination of Partition Co-efficient of Acetic Acid beteen Water and n-butanol) 5 Conductometric Titration for determination of the strength of a given HCl solution by titration against a standard NaOH solution. 6 ph-metric titration for determination of the strength of a given HCl solution against a standard NaOH solution