Quantitative Determination of Total Hardness In Drinking Water Essay

AbstractThis experiment is about the determination of peeing system asperity through the put on of involvedometric EDTA titration. Determination of piss validity is essential to ensure out the most suitable water rigor under feature circumstances. This was conducted for the purpose of applying the concept of complexometric titration victimisation an efficient chelating agent, EDTA. Sample mineral water was analyzed utilize standard EDTA with EBT as indi nookyt, and calcium ions posit in the dissolver were calculated to determine the clayeyness of the water strain. At the depot of the experiment, the results indicated that the mineral pattern water has large amounts of calcium and atomic number 12 ionsan signification of a hard water sample.INTRODUCTIONWater hardness is a measure of the amount of calcium and magnesium present in sample water. These calcium and magnesium ions have the capacity to replace sodium or potassium ions and form sparingly soluble products or precipitates. Water hardness is involved in various aspects of industrial and biochemical processes. Large amounts of ppm CaCO3 in water can form precipitates when interacted with soap and form rings cognise as scum in some(prenominal) utensils and appliances. The formation of these scum in electrical appliances degrades its efficiency and pass on eventu whollyy reduce its life span. In addition, these can casing impairments on fabric as well, and damage water treatment plants and piping systems at a water hardness of ccc ppm CaCO3.Calcium is necessary for aquatic animals such(prenominal) as fish. It serves animportant post in bone formation, blood clotting, and metabolic processes of the fish and prevents the loss of important salts in the body which helps in the functioning of its vital organs such as the heart. Small amounts of calcium in water can be life-threatening to aquatic organisms like the fish. Thus, determination of water hardness is important. adept method of determining water hardness is through complexometric titration. In this process, a ligand is involved in the said titration.Metal ion opposes with a particular ligand forming a complex and the equivalence point is determined by an indicator. Theligand workoutd in the experiment is Ethylenediaminetetraacetic back breaker (EDTA) with Eriochrome Black T indicator. EDTA is an efficient chelating agent and has an tycoon to bind with metal ions. Because of this, EDTA is also used in food preservation, an anti-coagulant in blood, and, when EDTA is combined with Fe(II), can even be used as an efficacious absorbent of harmful NO (nitric oxide). The purpose of this experiment is to determine the hardness of water through complexometric titration.METHODOLOGYBefore the actual experiment, solutions of ergocalciferol mL of 0.1000 M stock EDTA solution, 250 mL of 0.0100 M standard EDTA solution, 250 mL of 0.050 M standard CaCO3 solution, 50 mL of 0.0050 M working standard CaCO3 solution, and 250 mL of 1.0 M NH3-NH4+ soften solution were fain quantitatively. In this experiment, the titrant used was Ethylenediaminetetraacetic Acid (EDTA), a polydentate with six bonding sites. Polydentates aid in obtaining sharper endpoints since they react more only with cations. Likewise, reaction with polydentates only involves a single mistreat process compared to utilise monodentates as titrants which involves at least two negotiate species. Among polydentates, EDTA was chosen as the titrant since it is versatile and forms most sufficiently persistent chelates because of its several complexing sites which gives rise to a cage-like structure isolating the cations from solvent molecules.For the set of 500 mL of 0.1000 M stock EDTA solution, 18.6 g of Na2H2EDTA2H2O was weighed to the nearest 0.1 mg and was transferred into a 400 mL beaker. 200 mL of di quietened waterand 1.0 g MgCl26H2O crystals were added into the beaker and compound until the crystals were dissolved. MgCl26H2O was added to obtain a sharper endpoint since CaIn- complex ion is less stable and endpoint will come earlier than actual. The solution was heated for instant(prenominal) dissolution and NaOH pellets were added to the turbid solution to produce salt EDTA making the pH of the solution higher and increasing the solubility of the EDTA. Into a 500 mL volumetrical flaskful, the solution was transferred and was diluted to mark with distilled water. The solution was stored in a dry and clean reagent bottle. The 250 mL of 0.0100 M standard EDTA solution was hustling by getting 25 mL from 0.1000 M stock EDTA solution and diluting it to mark with distilled water in a 250 mL volumetric flask. For the preparation of 250 mL of 0.050 M standard CaCO3 solution, 1.2510 g of pure CaCO3 was weighed to the nearest 0.1mg into a 250 mL beaker and 20 mL distilled water was added.Drops of 6 M HCl were added until the CaCO3 was completely dissolved. The beaker was coered utilize a watch glass and was put everyplace a hot plate. The solution was evaporated until an amount of 10 mL was left. later cooling the solution, the washings were collected by rinsing the watch glass into the beaker using distilled water. 20 mL more distilled water was added into the solution and it was transferred into a 250-mL volumetric flask. The solution was diluted to mark and was stored in a plastic polyethylene bottle since glass bottle can l from each one and ions from it will back up the solution. The 50 mL of 0.0050 M working standard CaCO3 solution was prepared by dilution of 5 mL 0.050 M standard CaCO3 into a 50-mL volumetric flask. For NH3-NH4+ buffer solution of pH 10, 2.06 g of NH4Cl was dissolved in 14.3 mL of concentrated ammonia and was diluted to mark in a 250-mL volumetric flask. Buffer solution was used since buffers are resistant to pH motleys13.Maintaining the pH is important in preventing interference of other species during titration since different chelates form at a particular pH.14 For the standardization of 0.01 M EDTA Solution, 10 mL each of 0.0050 M working standard CaCO3 solution was transferred into each of the three 250-mL Erlenmeyer flask using a pipette. Then, into each flask, 75 mL of distilled water was added followed by 3 mL of the NH3-NH4+ buffer solution and 2-3 drops of Eriochrome Black T (EBT) indicator. Although use of EBT indicator is unsatisfactory in calcium, it is ideal to use in magnesium titration15, and since MgCl2 was put earlier, the number of calcium ions can be determineusing EBT indicator16. one and only(a) at a time, the solutions were titrated with the 0.010 M standard EDTA solution. Water sample was analyzed by measuring 50 mL of commercial mineral water Viva into each of the three 250-mL Erlenmeyer flask. Then, into each flask, 75 mL of distilled water was added followed by 3 mL of the NH3-NH4+ buffer solution and 2-3 drops of EBT indicator. cardinal at a time, the solutions were titrated with the 0.010 M standard EDTA solution. RESULTS AND DISCUSSIONComplexometric titration was used in the experiment since the reaction between the aqueous solutions of the analyte (CaCO3 solution, water sample) and titrant (EDTA) forms a complex. Which involves a coordination center composed of Ca2+ and Mg2+ and the chelating agent EDTA. EDTA, a weak vitriolic, commonly forms 11 stochiometric ratio when it reacts to form soluble complexes with metal ions, this means that a single endpoint would be observed. Most of the time EDTA reacts with metals regardless of their charges. These would all correlate to a sharp endpoint in titration and a gleam calculation in stoichiometry. Titration with EDTA is affected by several factors such as the existence of complex forming ions and of organic solvents that affects the stability of the complex, the metal ion components, and the pH wherein the titration was performed. The pH range for optimal indications using EBT indicator and for better results in titration using EDTA m ethod is from 8-10.Lower pH would form a colorless complex with EDTA while a high pH makes it hard to distinguish using the metal indicator In the experiment the pH was kept eternal at 10, this was possible with the presence of the buffer solution of NH3 NH4Cl. It has a buffer capacity that satisfies the optimal pH range. Buffer solutions resist pH swop that might be caused by other cations and the weak acid titrant, EDTA. Also, the indicator EBT would behave as it should be if there are no fluctuations in the pH. The specific pH was essential because at the pH of 10 EDTA would deprotonate however enough to bind with the metals involved. If too much buffer was added to the solution, the titration would yield uncollectible endpoints. For example the pH was at 12, the solution would be too staple that it might form precipitates with magnesium and calcium which in turn would cause different results. The endpoint of the solution in the first trial was blue devil so we opt not to pu t KCN in the solution. KCN bonds with ironso that iron would not affect the color change of the indicator. If iron is present in the sample it would affect the color endpoint and turn to regal instead of blue. Chemical equations that express the reaction in the titration can be shown in figure 1.Figure 1. Chemical equations involved in the titration.In the sample analysis of Viva mineral water, it contained 54mgCa/L and 14mgMg/L. After reason for the conglomeration hardness of the sample using ppm CaCO3 it was found out that the claimed total hardness was 192.6 ppm CaCO3 while the computed average ppm CaCO3 from the experiment was 139.5 ppm CaCO3this means that the calculated evaluate from the experiment is less than the calculated total hardness of Viva mineral water according to the indicated value in the label except still in the range of hard according to the water hardness cuticle in table 1. Table 1 Water Hardness ordered seriesThe unit ppm CaCO3 was used because water is mostly composed of calcium and magnesium ions. Both of these ions can be expressed in terms of CaCO3 One possible source of error is the human error from differentiating color change of the indicator EBT. The solution might have turned violet but not observed making the titrant endpoint wrong because of the presence of iron. other(a) possible sources of error are excess buffer solution that will increase pH, calibration error of pH meter, wrong volume reading, and over titration.SUMMARY AND CONCLUSIONThe Complex solutions were formed by titration with the chelating agent EDTA. With the use of complexometric titration the total hardness of water sample was determined. It was found out that the water hardness of Viva mineral water is classified as hard in terms of calcium and magnesium ions content that was expressed in terms of ppm CaCO3. The claimed total hardness of Viva Company is larger than the data-based value meaning it has less metal ion content than expected. The results of the experiment can be improved with the addition of KCN. 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