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determination of magnesium by edta titration calculations

to the EDTA titration method for the determination of total hardness, based on your past experience with the ETDA method (e.g., in CH 321.) h`. A variety of methods are available for locating the end point, including indicators and sensors that respond to a change in the solution conditions. PDF Determination of Mg by Titration with EDTA - Truman State University Now that we know something about EDTAs chemical properties, we are ready to evaluate its usefulness as a titrant. startxref Why is a small amount of the Mg2+EDTA complex added to the buffer? In addition to its properties as a ligand, EDTA is also a weak acid. 21 0 obj <> endobj Determination of Total Hardness by Titration with Standardized EDTA Determine the total hardness (Ca2+ and Mg2+) by using a volumetric pipet to pipet 25 mL of the unknown solution into a 250 mL Erlenmeyer flask. Complexometric determination of calcium - Titration and titrimetric methods PDF EDTA Titration of CalciumII and MagnesiumII - University of Delaware \[\textrm{MIn}^{n-}+\textrm Y^{4-}\rightarrow\textrm{MY}^{2-}+\textrm{In}^{m-}\]. Determination of Total Hardness of Water The objective of Table B of the experiment is to determine the total hardness of the given water samples: well water, tap water, and seawater. The titration uses, \[\mathrm{\dfrac{0.05831\;mol\;EDTA}{L}\times 0.02614\;L\;EDTA=1.524\times10^{-3}\;mol\;EDTA}\]. Water hardness is determined by the total concentration of magnesium and calcium. Titration is a method to determine the unknown concentration of a specific substance (analyte) dissolved in a sample of known concentration. 0000008376 00000 n which means the sample contains 1.524103 mol Ni. In this section we demonstrate a simple method for sketching a complexation titration curve. PDF Experiment2 Analysis*of*magnesium* \[\begin{align} One consequence of this is that the conditional formation constant for the metalindicator complex depends on the titrands pH. If desired, calcium could then be estimated by subtracting the magnesium titration (d) from the titration for calcium plus magnesium (a). The reaction between Mg2+ ions and EDTA can be represented like this. Repeat the titrations to obtain concordant values. startxref PDF Titration of Chloride - YSI The equivalence point of a complexation titration occurs when we react stoichiometrically equivalent amounts of titrand and titrant. The end point is determined using p-dimethylaminobenzalrhodamine as an indicator, with the solution turning from a yellow to a salmon color in the presence of excess Ag+. The experimental approach is essentially identical to that described earlier for an acidbase titration, to which you may refer. Obtain a small volume of your unknown and make a 10x dilution of the unknown. To prevent an interference the pH is adjusted to 1213, precipitating Mg2+ as Mg(OH)2. 1 Answer anor277 . The charged species in the eluent will displace those which were in the sample and these will flow to the detector. Add 10 mL of ammonia buffer, 50 mL of distilled water and 1 mL of Eriochrome Black T indicator Figure 9.31 Examples of spectrophotometric titration curves: (a) only the titrand absorbs; (b) only the titrant absorbs; (c) only the product of the titration reaction absorbs; (d) both the titrand and the titrant absorb; (e) both the titration reactions product and the titrant absorb; (f) only the indicator absorbs. Aim: Determine the total hardness of given water samples. The molarity of EDTA in the titrant is, \[\mathrm{\dfrac{4.068\times10^{-4}\;mol\;EDTA}{0.04263\;L\;EDTA} = 9.543\times10^{-3}\;M\;EDTA}\]. If the metalindicator complex is too strong, the change in color occurs after the equivalence point. The stoichiometry between EDTA and each metal ion is 1:1. 0000008621 00000 n teacher harriet voice shawne jackson; least stressful physician assistant specialties; grandma's marathon elevation gain; describe key elements of partnership working with external organisations; The excess EDTA is then titrated with 0.01113 M Mg2+, requiring 4.23 mL to reach the end point. Hardness is determined by titrating with EDTA at a buffered pH of 10. In addition, EDTA must compete with NH3 for the Cd2+. ! &=\dfrac{\textrm{(0.0100 M)(30.0 mL)} - (5.00\times10^{-3}\textrm{ M})(\textrm{50.0 mL})}{\textrm{50.0 mL + 30.0 mL}}\\ Note that after the equivalence point, the titrands solution is a metalligand complexation buffer, with pCd determined by CEDTA and [CdY2]. Titrate with EDTA solution till the color changes to blue. 5CJ OJ QJ ^J aJ #h`. Use the standard EDTA solution to titrate the hard water. PDF EDTA Titrations 2: Analysis of Calcium in a Supplement Tablet; Analysis Some!students! After transferring a 50.00-mL portion of this solution to a 250-mL Erlenmeyer flask, the pH was adjusted by adding 5 mL of a pH 10 NH3NH4Cl buffer containing a small amount of Mg2+EDTA. 6ADIDnu1cGM?froF%a,;on_Qw!"eEA#z@$\Xx0f 80BUGc77 b`Y]TkEZt0Yu}5A\vm5Fvh5A/VbgvZd Answered: Calculate the % Copper in the alloy | bartleby OJ QJ UmH nH u h CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ hs CJ OJ QJ ^J aJ R T V Z v x | qcU? 0000041216 00000 n 3 22. (% w / w) = Volume. When the titration is complete, raising the pH to 9 allows for the titration of Ca2+. Given the Mg2+: EDTA ratio of 1 : 1, calculate the concentration of your EDTA solution. \end{align}\]. Magnesium. Indicator. where Kf is a pH-dependent conditional formation constant. Lab 6 Report - Experiment 6: Determination of Magnesium by To calculate magnesium solution concentration use EBAS - stoichiometry calculator. The reaction of Mg2+ with EDTA may be expressed as: Mg2+ + H2Y2- = MgY-2 + 2H+ The structure of EDTA and the magnesium-EDTA complex (without the hydrogen atoms) is shown below: The endpoint of the titration is determined by the . A second 50.00-mL aliquot was treated with hexamethylenetetramine to mask the Cr. Complexometric Determination of Magnesium using EDTA EDTA Procedure Ethylenediaminetetraacetic Acid Procedure Preparing a Standard EDTA Solution Reactions 1.Weighing by difference 0.9g of EDTA 2.Quantitatively transfer it to a 250 mL volumetric flask 3.Add a 2-3mL of amonia buffer (pH 10) See the final side comment in the previous section for an explanation of why we are ignoring the effect of NH3 on the concentration of Cd2+. (PDF) Titrimetric Determination of Calcium Content of - ResearchGate 0000014114 00000 n For a titration using EDTA, the stoichiometry is always 1:1. In the later case, Ag+ or Hg2+ are suitable titrants. PDF ESTIMATION OF HARDNESS OF WATER BY EDTA METHOD - University of Babylon The same unknown which was titrated will be analyzed by IC. The specific form of EDTA in reaction 9.9 is the predominate species only at pH levels greater than 10.17. Practical analytical applications of complexation titrimetry were slow to develop because many metals and ligands form a series of metalligand complexes. A 0.7176-g sample of the alloy was dissolved in HNO3 and diluted to 250 mL in a volumetric flask. The titrations end point is signaled by the indicator calmagite. Another common method is the determination by . Elution of the compounds of interest is then done using a weekly acidic solution. The value of Cd2+ depends on the concentration of NH3. 0000002676 00000 n To illustrate the formation of a metalEDTA complex, lets consider the reaction between Cd2+ and EDTA, \[\mathrm{Cd^{2+}}(aq)+\mathrm{Y^{4-}}(aq)\rightleftharpoons \mathrm{CdY^{2-}}(aq)\tag{9.9}\], where Y4 is a shorthand notation for the fully deprotonated form of EDTA shown in Figure 9.26a. <<36346646DDCF9348ABBBE0F376F142E7>]/Prev 138126/XRefStm 1156>> From Table 9.10 and Table 9.11 we find that Y4 is 0.35 at a pH of 10, and that Cd2+ is 0.0881 when the concentration of NH3 is 0.0100 M. Using these values, the conditional formation constant is, \[K_\textrm f''=K_\textrm f \times \alpha_\mathrm{Y^{4-}}\times\alpha_\mathrm{Cd^{2+}}=(2.9\times10^{16})(0.37)(0.0881)=9.5\times10^{14}\], Because Kf is so large, we can treat the titration reaction, \[\textrm{Cd}^{2+}(aq)+\textrm Y^{4-}(aq)\rightarrow \textrm{CdY}^{2-}(aq)\]. Dilute 20ml of the sample in Erlenmeyer flask to 40ml by adding 20ml of distilled water. Determination of Mg by Titration with EDTA INTRODUCTION hb``c``ie`a`p l@q.I7!$1)wP*Sy-+]Ku4y^TQP h Q2qq 8LJb2rO.dqukR Cp/N8XbS0X_.fhhbCKLg4o\4i uB The actual number of coordination sites depends on the size of the metal ion, however, all metalEDTA complexes have a 1:1 stoichiometry. Add a pinch of Eriochrome BlackT ground with sodium chloride (100mg of indicator plus 20g of analytical grade NaCl). In the process of titration, both the volumetric addition of titra Acid-base titrations (video) | Khan Academy Titration . Determination of Calcium and Magnesium in Water . 0 1.The colour change at the end point (blue to purple) in the Titration I is due to [Mark X in the correct box.] EDTA Titration: Calcium in Calcium Supplements Student Handout Purpose To determine the amount of calcium in a calcium supplement tablet by EDTA titration. The other three methods consisted of direct titrations (d) of mangesium with EDTA to the EBT endpoint after calcium had been removed. Otherwise, the calcium will precipitate and either you'll have no endpoint or a weak endpoint. 243 26 0000000676 00000 n Complexometric Titration Experiment - Principle, Procedure and Observation First, we calculate the concentration of CdY2. Titanium dioxide is used in many cosmetic products. Calmagite is used as an indicator. Transfer a 10.00-mL aliquot of sample to a titration flask, adjust the pH with 1-M NaOH until the pH is about 10 (pH paper or meter) and add . Therefore the total hardness of water can be determination by edta titration method. Architektw 1405-270 MarkiPoland, free trial version of the stoichiometry calculator. 0000024212 00000 n Sketch titration curves for the titration of 50.0 mL of 5.00103 M Cd2+ with 0.0100 M EDTA (a) at a pH of 10 and (b) at a pH of 7. For each of the three titrations, therefore, we can easily equate the moles of EDTA to the moles of metal ions that are titrated. PDF Determination of water hardness from common water sources using flame Adding a small amount of Mg2+EDTA to the titrand gives a sharper end point. At a pH of 3 EDTA reacts only with Ni2+. Solutions of EDTA are prepared from its soluble disodium salt, Na2H2Y2H2O and standardized by titrating against a solution made from the primary standard CaCO3. \[C_\textrm{EDTA}=[\mathrm{H_6Y^{2+}}]+[\mathrm{H_5Y^+}]+[\mathrm{H_4Y}]+[\mathrm{H_3Y^-}]+[\mathrm{H_2Y^{2-}}]+[\mathrm{HY^{3-}}]+[\mathrm{Y^{4-}}]\]. 0000002034 00000 n It is unfit for drinking, bathing, washing and it also forms scales in &=\dfrac{(5.00\times10^{-3}\textrm{ M})(\textrm{50.0 mL}) - (\textrm{0.0100 M})(\textrm{5.0 mL})}{\textrm{50.0 mL + 5.0 mL}}=3.64\times10^{-3}\textrm{ M} Because not all the unreacted Cd2+ is freesome is complexed with NH3we must account for the presence of NH3. Estimation of magnesium ions in the given sample: 20 mL of the given sample of solution containing magnesium ions is pipetted into a 250 Erlenmeyer flask, the solution is diluted to 100 mL, warmed to 40 degrees C, 2 mL of a buffer solution of pH 10 is added followed by 4 drops of Eriochrome black T solution. Prepare a standard solution of magnesium sulfate and titrate it against the given EDTA solution using Eriochrome Black T as the indicator. 0000002997 00000 n We can solve for the equilibrium concentration of CCd using Kf and then calculate [Cd2+] using Cd2+. xref At the equivalence point we know that moles EDTA = moles Cd2 + MEDTA VEDTA = MCd VCd Substituting in known values, we find that it requires Veq = VEDTA = MCdVCd MEDTA = (5.00 10 3 M)(50.0 mL) 0.0100 M = 25.0 mL From the data you will determine the calcium and magnesium concentrations as well as total hardness. For removal of calcium, three precipitation procedures were compared. The total concentrations of Cd2+, CCd, and the total concentration of EDTA, CEDTA, are equal. Figure 9.29 Illustrations showing the steps in sketching an approximate titration curve for the titration of 50.0 mL of 5.00 103 M Cd2+ with 0.0100 M EDTA in the presence of 0.0100 M NH3: (a) locating the equivalence point volume; (b) plotting two points before the equivalence point; (c) plotting two points after the equivalence point; (d) preliminary approximation of titration curve using straight-lines; (e) final approximation of titration curve using a smooth curve; (f) comparison of approximate titration curve (solid black line) and exact titration curve (dashed red line). Table 2 Determination of Total Hardness of Water Trials Volume of Sample (mL) Nt. A 50.00-mL aliquot of the sample, treated with pyrophosphate to mask the Fe and Cr, required 26.14 mL of 0.05831 M EDTA to reach the murexide end point. A similar calculation should convince you that pCd = logKf when the volume of EDTA is 2Veq. Table 9.14 provides examples of metallochromic indicators and the metal ions and pH conditions for which they are useful. H|W$WL-_ |`J+l$gFI&m}}oaQfl%/|}8vP)DV|{*{H [1)3udN{L8IC 6V ;2q!ZqRSs9& yqQi.l{TtnMIrW:r9u$ +G>I"vVu/|;G k-`Jl_Yv]:Ip,Ab*}xqd e9:3x{HT8| KR[@@ZKRS1llq=AE![3 !pb Report the molar concentration of EDTA in the titrant. mole( of( EDTA4-perliter,and&VEDTA( is( the( volume( of EDTA 4- (aq)inunitsofliter neededtoreachtheendpoint.If( you followed instructions, V Mg =0.025Land( C EDTA =( The solution is warmed to 40 degrees C and titrated against EDTA taken in the burette. If the sample does not contain any Mg2+ as a source of hardness, then the titrations end point is poorly defined, leading to inaccurate and imprecise results. ! The first method is calculation based method and the second method is titration method using EDTA. Complexation Titration is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. Although each method is unique, the following description of the determination of the hardness of water provides an instructive example of a typical procedure. Add 12 drops of indicator and titrate with a standard solution of EDTA until the red-to-blue end point is reached (Figure 9.32). where VEDTA and VCu are, respectively, the volumes of EDTA and Cu. EDTA can form four or six coordination bonds with a metal ion. Before the equivalence point, Cd2+ is present in excess and pCd is determined by the concentration of unreacted Cd2+. 4 Sample Calculations (Cont.) Repeat the titration twice. (not!all!of . EDTA Titration for Determination of calcium and magnesium Calcium and Magnesium ion concentration determination with EDTA titration 56,512 views Dec 12, 2016 451 Dislike Share Save Missy G. 150 subscribers CHEM 249 Extra credit by Heydi Dutan and. Although most divalent and trivalent metal ions contribute to hardness, the most important are Ca2+ and Mg2+. Protocol B: Determination of Aluminum Content Alone Pipet a 10.00 ml aliquot of the antacid sample solution into a 125 ml. Currently, titration methods are the most common protocol for the determination of water hardness, but investigation of instrumental techniques can improve efficiency. As we add EDTA it reacts first with free metal ions, and then displaces the indicator from MInn. The solution was then made alkaline by ammonium hydroxide. What problems might you expect at a higher pH or a lower pH? Note that the titration curves y-axis is not the actual absorbance, A, but a corrected absorbance, Acorr, \[A_\textrm{corr}=A\times\dfrac{V_\textrm{EDTA}+V_\textrm{Cu}}{V_\textrm{Cu}}\]. The description here is based on Method 2340C as published in Standard Methods for the Examination of Water and Wastewater, 20th Ed., American Public Health Association: Washington, D. C., 1998. (Note that in this example, the analyte is the titrant. The concentration of Cl in a 100.0-mL sample of water from a freshwater aquifer was tested for the encroachment of sea water by titrating with 0.0516 M Hg(NO3)2. ^.FF OUJc}}J4 z JT'e!u3&. Report the concentration of Cl, in mg/L, in the aquifer. PDF Experiment 5 EDTA Titration: Calcium in Calcium Supplements PDF Determination of Calcium, Magnesium, and Sodium by Atomic Spectrophotometry endstream endobj 244 0 obj <>/Metadata 80 0 R/Pages 79 0 R/StructTreeRoot 82 0 R/Type/Catalog/ViewerPreferences<>>> endobj 245 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]>>/Rotate 0/StructParents 0/TrimBox[0.0 0.0 595.276 841.89]/Type/Page>> endobj 246 0 obj <> endobj 247 0 obj <>stream Table 9.10 provides values of Y4 for selected pH levels. 13.1) react with EDTA in . A buffer solution is prepared for maintaining the pH of about 10. Method C, the EDTA titration method, measures the calcium and magnesium ions and may be applied with appro-priate modication to any kind of water. h% CJ OJ QJ ^J aJ mHsH hk h, CJ OJ QJ ^J aJ h% CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ hs CJ OJ QJ ^J aJ h, CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ +hk hk 5CJ OJ QJ ^J aJ mHsH(h% 5CJ H*OJ QJ ^J aJ mHsH pZK9( hk h, CJ OJ QJ ^J aJ #h, h% 5CJ OJ QJ ^J aJ hs 5CJ OJ QJ ^J aJ +h, h% 5CJ OJ QJ ^J aJ mHsH.h, h, 5CJ H*OJ QJ ^J aJ mHsH .h B = mg CaCO3 equivalent to 1 ml EDTA Titrant. Calcium is determined at pH 12 where magnesium is quantitatively precipitated as the hydroxide and will not react with EDTA. Add 1 mL of ammonia buffer to bring the pH to 100.1. ! 2. In this method buffer solution is used for attain suitable condition i.e pH level above 9 for the titration. 1. EDTA is a versatile titrant that can be used to analyze virtually all metal ions. For example, after adding 5.0 mL of EDTA, the total concentration of Cd2+ is, \[\begin{align} The solid lines are equivalent to a step on a conventional ladder diagram, indicating conditions where two (or three) species are equal in concentration. the reason for adding Mg-EDTA complex as part of the NH 4 Cl - NH 4 OH system explained in terms of requirement of sufficient inactive Mg2+ ions to provide a sharp colour change at the endpoint. The reason we can use pH to provide selectivity is shown in Figure 9.34a. hs 5>*CJ OJ QJ ^J aJ mHsH 1h Most metallochromic indicators also are weak acids. An analysis done on a series of samples with known concentrations is utilized to build a calibration curve. For the titration of Mg2+, one must buffer the solution to a pH of 10 so that complex formation will be quantitative. PDF HARDNESS (2340)/EDTA Titrimetric Method 2-37 2340 HARDNESS* 2340 A of which 1.524103 mol are used to titrate Ni. Calcium can be precipitated as carbonate or oxalate, although presence of oxalates may make end point detection difficult. 3. CJ OJ QJ ^J aJ hLS CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ h- CJ OJ QJ ^J aJ t v 0 6 F H J L N ` b B C k l m n o r #hH hH >*CJ OJ QJ ^J aJ hH CJ OJ QJ ^J aJ hk hH CJ OJ QJ ^J aJ h% CJ OJ QJ ^J aJ hLS h% CJ OJ QJ ^J aJ hLS CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ hp CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ $ 1 4  |n||||]]||n| h, h% CJ OJ QJ ^J aJ hLS CJ OJ QJ ^J aJ hp CJ OJ QJ ^J aJ h, h% CJ OJ QJ ^J aJ hk hk CJ OJ QJ ^J aJ h% CJ OJ QJ ^J aJ #h hH CJ H*OJ QJ ^J aJ hH CJ OJ QJ ^J aJ #hH hH >*CJ OJ QJ ^J aJ &h hH >*CJ H*OJ QJ ^J aJ !o | } If MInn and Inm have different colors, then the change in color signals the end point. is large, its equilibrium position lies far to the right. Compare your sketches to the calculated titration curves from Practice Exercise 9.12. What is the principle of EDTA titration? - Studybuff A red to blue end point is possible if we maintain the titrands pH in the range 8.511. Standard magnesium solution, 0.05 M. Dissolve 1.216 g of high purity mag- nesium (Belmont 99.8%) in 200 ml of 20% hydrochloric acid and dilute to 11. 268 0 obj <>stream 0000001481 00000 n 0000001814 00000 n In an EDTA titration of natural water samples, the two metals are determined together. Determination of Calcium and Magnesium in Milk by E.D.T.A. Titration At a pH of 3, however, the conditional formation constant of 1.23 is so small that very little Ca2+ reacts with the EDTA. \end{align}\], To calculate the concentration of free Cd2+ we use equation 9.13, \[[\mathrm{Cd^{2+}}] = \alpha_\mathrm{Cd^{2+}} \times C_\textrm{Cd} = (0.0881)(3.64\times10^{-4}\textrm{ M})=3.21\times10^{-4}\textrm{ M}\], \[\textrm{pCd}=-\log[\mathrm{Cd^{2+}}]=-\log(3.21\times10^{-4}) = 3.49\]. In an acid-base titration, the titrant is a strong base or a strong acid, and the analyte is an acid or a base, respectively. The quantitative relationship between the titrand and the titrant is determined by the stoichiometry of the titration reaction. Add 2 mL of a buffer solution of pH 10. 0000001156 00000 n trailer a mineral analysis is performed, hardness by calculation can be reported. Complexation Titration: Determination of Total Hardness of Water Calculate the number of grams of pure calcium carbonate required to prepare a 100.0 mL standard calcium solution that would require ~35 mL of 0.01 M EDTA for titration of a 10.00 mL aliquot: g CaCO 3 = M EDTA x 0.035L x 1 mol CaCO 3/1 mol EDTA x MM CaCO 3 x 100.0mL/10.00mL 3. The concentration of Ca2+ ions is usually expressed as ppm CaCO 3 in the water sample. If at least one species in a complexation titration absorbs electromagnetic radiation, we can identify the end point by monitoring the titrands absorbance at a carefully selected wavelength. The scale of operations, accuracy, precision, sensitivity, time, and cost of a complexation titration are similar to those described earlier for acidbase titrations. Most indicators for complexation titrations are organic dyesknown as metallochromic indicatorsthat form stable complexes with metal ions. To do so we need to know the shape of a complexometric EDTA titration curve. 0000023545 00000 n %Srr~81@ n0/Mm`:5 A)r=AKVvY Ri9~Uvhug BAp$eK,v$R!36e8"@` lab report 6 determination of water hardness Calcium can be determined by EDTA titration in solution of 0.1 M sodium hydroxide (pH 12-13) against murexide. Thus one simply needs to determine the area under the curve of the unknown and use the calibration curve to find the unknown concentration. DOC Experiment 5: EDTA Determination of Calcium and Magnesium The red arrows indicate the end points for each titration curve. To determine the concentration of each metal separately, we need to do an additional measurement that is selective for one of the two metals. In the determination of water hardness, ethylene-diaminetetraacetic acid (EDTA) is used as the titrant that complexes Ca2+ and Mg2+ ions. The ladder diagram defines pMg values where MgIn and HIn are predominate species. When the reaction between the analyte and titrant is complete, you can observe a change in the color of the solution or pH changes. Even if a suitable indicator does not exist, it is often possible to complete an EDTA titration by introducing a small amount of a secondary metalEDTA complex, if the secondary metal ion forms a stronger complex with the indicator and a weaker complex with EDTA than the analyte. h% 5>*CJ OJ QJ ^J aJ mHsH +h, h, 5CJ OJ QJ ^J aJ mHsH { ~ " : kWI8 h, h% CJ OJ QJ ^J aJ hp CJ OJ QJ ^J aJ &h, h% 5CJ OJ QJ \^J aJ &hk hLS 5CJ OJ QJ \^J aJ &hLS h% 5CJ OJ QJ \^J aJ hlx% 5CJ OJ QJ \^J aJ hs CJ OJ QJ ^J aJ &h, h, 6CJ OJ QJ ]^J aJ )hs h% 6CJ H*OJ QJ ]^J aJ hs 6CJ OJ QJ ]^J aJ &h, h% 6CJ OJ QJ ]^J aJ : $ ( * , .

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determination of magnesium by edta titration calculations

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