{"id":371,"date":"2019-04-15T09:18:06","date_gmt":"2019-04-15T09:18:06","guid":{"rendered":"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/?post_type=chapter&#038;p=371"},"modified":"2019-04-15T10:06:24","modified_gmt":"2019-04-15T10:06:24","slug":"precipitation-argentometric-titrations","status":"publish","type":"chapter","link":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/chapter\/precipitation-argentometric-titrations\/","title":{"rendered":"Precipitation (Argentometric) Titrations"},"content":{"raw":"\r\n<div><span style=\"float: right\"><a href=\"https:\/\/youtu.be\/pYNPbUxqJWE\" target=\"_blank\" rel=\"noopener\"><img src=\"http:\/\/epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/2018\/11\/download.png\" alt=\"epgp books\" width=\"75px\" height=\"75px;\" \/><\/a>\r\n<\/span><\/div>\r\n\r\n<div>\r\n\r\n&nbsp;\r\n\r\n1. What are precipitation reactions?\r\n\r\n2. What are solubility product and ionic product?\r\n\r\n3. What are the factors effecting solubility?\r\n\r\n4. What are argentometric titrations?\r\n\r\n5. How is the end point of precipitation titration?\r\n\r\n6. What are the applications of precipitation titration?\r\n\r\n<\/div>\r\n<div>\r\n\r\n&nbsp;\r\n<p style=\"text-align: justify\"><strong>1.\u00a0<\/strong><strong>Precipitation Titration: <\/strong>Precipitation titrations involve the stoichiometric reaction of standard precipitating agent with analyte. Precipitation titrations involving the use of silver ion as precipitating agent are classified as argentometric titrations<strong>.<\/strong><\/p>\r\n&nbsp;\r\n\r\n<strong>1\u00a0<\/strong><strong>Basic Requirements: <\/strong>The precipitate formed should have a definite stoichiometric.\r\n\r\n\u2022 The equilibrium between the precipitate and its ions in solution much be attained rapidly.\r\n\r\n\u2022 The precipitate must be of low solubility in the solution i.e., low solubility product.\r\n\r\n\u2022\u00a0 Suitable method for the detection of stoichiometric end-point of the titration.\r\n\r\n&nbsp;\r\n\r\n<strong>2\u00a0<\/strong><strong>Solubility Product:<\/strong>\r\n\r\nWhat happens when a sparingly soluble salt is put into a solvent?\r\n\r\n<img class=\"aligncenter size-full wp-image-375\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2.png\" alt=\"\" width=\"595\" height=\"200\" \/>\r\n<p style=\"text-align: center\"><strong>Figure 1: Stages of dissolution of salt<\/strong><\/p>\r\nAn equilibrium exists between a partially soluble substance and its solution\r\n<table class=\"aligncenter\" style=\"width: 60%\" border=\"1\">\r\n<tbody>\r\n<tr>\r\n<td>For Example<\/td>\r\n<td><\/td>\r\n<\/tr>\r\n<tr>\r\n<td>BaSO<sub>4<\/sub> (s)<strong>\u21cc<\/strong><\/td>\r\n<td>Ba<sup>2+<\/sup> (aq) + SO<sub>4<\/sub><sup>2-<\/sup> (aq)<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nK\u00a0 = [Ba<sup>2+<\/sup> (aq)][SO4<sup>2-<\/sup> (aq)] \/ [BaSO<sub>4<\/sub>(s)] K = K<em>sp<\/em>, the solubility-product constant, as [BaSO<sub>4<\/sub> (s)] = unity\r\n\r\n<span style=\"font-size: 1em;text-align: initial\">K<\/span><em style=\"font-size: 1em;text-align: initial\">sp<\/em><span style=\"font-size: 1em;text-align: initial\"> = [Ba<sup>2+<\/sup>(aq)][SO<sub>4<\/sub><sup>2-<\/sup>(aq)]<\/span>\r\n\r\n<\/div>\r\n<div>\r\n<p style=\"text-align: justify\">Thus, Solubility Product (K<em>sp<\/em>) is defined as equilibrium constant for the equilibrium between an ionic solid and its saturated solution.<\/p>\r\n&nbsp;\r\n<p style=\"text-align: justify\"><strong>2.1<\/strong>\u00a0<em>General Expression for Solubility Product:<\/em><\/p>\r\n<p style=\"text-align: justify\">AaBb(s) aAb+ (aq) + bBa- (aq)<\/p>\r\n<p style=\"text-align: justify\">K<em>sp<\/em> = <strong>[A<\/strong><strong>b+<\/strong><strong>]<\/strong><strong>a<\/strong> <strong>[B<\/strong><strong>a-<\/strong><strong>]<\/strong><strong>b<\/strong><\/p>\r\n<p style=\"text-align: justify\">Example: PbI2 (s)\u00a0 Pb2+ + 2 I-K<em>sp<\/em> = [Pb2+] [I-]2<\/p>\r\n<p style=\"text-align: justify\">Higher Ksp indicates high molar solubility; whereas lower Ksp indicates low molar solubility of the salt e.g. AgCl has lower solubility than NaCl.<\/p>\r\n&nbsp;\r\n<p style=\"text-align: justify\"><strong>3\u00a0<\/strong><strong>Conditions for Precipitation:<\/strong><\/p>\r\n\r\n<ul>\r\n \t<li style=\"text-align: justify\">\u00a0Precipitation is reverse of the dissolution phenomenon<\/li>\r\n<\/ul>\r\n&nbsp;\r\n<p style=\"text-align: justify\"><strong>3.1 Ionic Product: <\/strong>ionic product is the term given for the product of the concentration of cation and anion raised to the power of their respective stoichiometry in the salt.<\/p>\r\n\r\n<ul>\r\n \t<li style=\"text-align: justify\">Ionic product is the evaluation of the strength of ions under non-equilibrium condition. e.g. Ionic Product of BaCl2 would be given by Q<em>sp<\/em> = [Ba2+(aq)][Cl-(aq)]2<\/li>\r\n \t<li><em>Q<\/em>sp =<em> K<\/em>sp \u00e8 saturated solution, but no precipitate<\/li>\r\n \t<li>Qsp &gt; Ksp \u00e8 saturated solution, with precipitate<\/li>\r\n \t<li><em style=\"text-align: initial;font-size: 1em\">Q<\/em><span style=\"text-align: initial;font-size: 1em\">sp &lt;<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">sp \u00e8 unsaturated solution,<\/span><\/li>\r\n<\/ul>\r\n&nbsp;\r\n\r\n<strong>3.2<\/strong>\u00a0<strong>Factors Affecting Solubility \/ Precipitation<\/strong>\r\n\r\n\u2022\u00a0 Temperature\r\n\r\n\u2022\u00a0 Common ion effect\r\n\r\n\u2022\u00a0 Salt effect\r\n\r\n\u2022\u00a0 pH of solution\r\n\r\n\u2022\u00a0 Formation of complex ion\r\n\r\n<strong>3.2.1<\/strong>\u00a0\u00a0\u00a0\u00a0 <strong>Common Ion Effect<\/strong>\r\n\r\n\u2022\u00a0 Consider the following solubility equilibrium:\r\n\r\n<span style=\"font-size: 1em;text-align: initial\">AgCl(s) <\/span><strong style=\"font-size: 1em;text-align: initial\">\u21cc<\/strong><span style=\"font-size: 1em;text-align: initial\"> Ag+(aq) + Cl-(aq); <\/span><em style=\"font-size: 1em;text-align: initial\">K<\/em><span style=\"font-size: 1em;text-align: initial\">sp = 1.6 x 10-10<\/span>\r\n\r\n<\/div>\r\n<div>\r\n\r\n\u2022\u00a0 The solubility of AgCl is 1.3 x 10-5 mol\/L at 25oC.\r\n<p style=\"text-align: justify\">\u2022\u00a0 If NaCl is added, equilibrium shifts left due to increase in [Cl<sup>-<\/sup>] and more AgCl will precipitate out. For example, if [Cl-] = 1.0 x 10-2 M,<\/p>\r\n<p style=\"text-align: justify\">\u2022\u00a0 Solubility of AgCl = (1.6 x 10-10)\/(1.0 x 10-2)=\u00a0 1.6 x 10-8 mol\/L<\/p>\r\n&nbsp;\r\n\r\n<strong>3.2.2\u00a0\u00a0\u00a0 Effect of pH on Solubility<\/strong>\r\n<ul>\r\n \t<li>Consider the following equilibrium: Ag3PO4(s) <strong>\u21cc<\/strong> 3Ag+(aq) + PO43-(aq);<\/li>\r\n \t<li>\u00a0If HNO3 is added, the following reaction occurs: H3O+(aq) + PO43-(aq) <strong>\u21cc<\/strong> HPO42-(aq) + H2O<\/li>\r\n \t<li><span style=\"text-align: initial;font-size: 1em\">Consider the following equilibrium: Mg(OH)2(s) <\/span><strong style=\"text-align: initial;font-size: 1em\">\u21cc<\/strong><span style=\"text-align: initial;font-size: 1em\"> Mg2+(aq) + 2 OH-(aq);<\/span><\/li>\r\n \t<li>\u00a0Increasing the pH means increasing [OH-] and equilibrium will shift to the left, causing some of Mg(OH)2 to precipitate out.<\/li>\r\n<\/ul>\r\n<strong>3.2.3\u00a0\u00a0\u00a0 Formation of Complex Ions on Solubility<\/strong>\r\n<ul>\r\n \t<li>Many transition metals ions have strong affinity for ligands to form complex ions.<\/li>\r\n \t<li>Ligands are molecules, such as H2O, NH3 and CO, or anions, such as F-, CN- and S2O32-.<\/li>\r\n \t<li>Complexes are soluble \u2013 thus, the formation of complex ions increases solubility of slightly soluble ionic compounds.<\/li>\r\n \t<li>Consider the following equilibria:<\/li>\r\n \t<li>Combining the two equations yields:AgCl(s) + 2NH<sub>3<\/sub>(aq) <strong style=\"text-align: initial;font-size: 1em\">\u21cc<\/strong><span style=\"text-align: initial;font-size: 1em\"> Ag(NH<sub>3<\/sub>)<sup>2+<\/sup>(aq) + Cl-(aq);\u00a0<\/span><em style=\"text-align: initial;font-size: 1em\">K<\/em><span style=\"text-align: initial;font-size: 1em\">net =<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">sp x<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">f = (1.6 x 10<sup>-10<\/sup>) x (1.7 x 10<sup>7<\/sup>)<\/span>=\u00a0 <strong style=\"text-align: initial;font-size: 1em\">2.7 x 10<\/strong><strong style=\"text-align: initial;font-size: 1em\">-3<\/strong><\/li>\r\n \t<li><em style=\"text-align: initial;font-size: 1em\">K<\/em><span style=\"text-align: initial;font-size: 1em\">net &gt;<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">sp implies that AgCl is more soluble in aqueous NH<sub>3<\/sub> than in water.<\/span><\/li>\r\n \t<li>Consider the following case: 20.0 mL of 0.025 M Pb(NO3)2 is added to 30.0 mL of 0.10 M NaCl. Predict if precipitate of PbCl2 will form. (<em style=\"text-align: initial;font-size: 1em\">Ksp<\/em><span style=\"text-align: initial;font-size: 1em\"> for PbCl2 = 1.6 x 10-5)<\/span><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n\r\nCalculation:\r\n\r\n[Pb<sup>2+<\/sup>] = (20.0 mL x 0.025 M)\/(50.0 mL) = 0.010 M\r\n\r\n[Cl<sup>-<\/sup>] = (30.0 mL x 0.10 M)\/(50.0 mL) = 0.060 M\r\n\r\n<em>Q<\/em>sp = [Pb<sup>2+<\/sup>][Cl<sup>-<\/sup>]<sup>2<\/sup> = (0.010 M)(0.060 M)2<em>\u00a0 <\/em>= 3.6 x 10-5\r\n\r\n<strong><em>Q<\/em><\/strong><strong>sp<\/strong> <strong>&gt;<em> K<\/em><\/strong><strong>sp<\/strong><strong><em>\u00a0 <\/em><\/strong><strong>\u00e8<\/strong> <strong>precipitate of PbCl<\/strong><strong>2<\/strong> <strong>will form.<\/strong>\r\n<p style=\"text-align: justify\"><strong>4\u00a0<\/strong><strong>Argentometric Titration: <\/strong>Argentometric titration is carried out by addition of standardized AgNO3 solution to the analyte solution.Upon increasing the concentration of AgNO3 in the titre to an extent that the ionic product of Ag+ and Cl- exceeds the solubility product, a suspension is formed. This increase in the titrant leads to depletion of titre and increase in the \u2013log10 [Cl-]. The titration curve is normally broken down in three regions for the purposes of calculation and a function for pCl is determined for each region:<\/p>\r\n<strong>4.1 <\/strong>Pre-equivalence region\r\n\r\n<strong>4.2 <\/strong>Equivalence point\r\n\r\n<strong>4.3 <\/strong>Post-equivalence region\r\n\r\n<\/div>\r\n<div>\r\n\r\n<img class=\"aligncenter size-full wp-image-376\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1.png\" alt=\"\" width=\"351\" height=\"348\" \/>\r\n<p style=\"text-align: center\"><strong>Figure 2:<\/strong>\u00a0\u00a0\u00a0\u00a0 <strong>The precipitation titration response curve for argentometric titration of chloride ions\u00a0<\/strong><strong>Argentometric Titration:<\/strong><\/p>\r\n&nbsp;\r\n\r\n<img class=\"aligncenter size-full wp-image-377\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2.png\" alt=\"\" width=\"517\" height=\"303\" \/><strong>Table 1: The progress of argentometric titration for chloride ions Calculation at S. No. 2: 10.00 mL Titrant Added (Pre-equivalence Region)<\/strong>\r\n\r\nmmol Cl<sup>-<\/sup> started = 25.00 mL 0.100 M = 2.50 mmol\r\n\r\n<\/div>\r\n<div>\r\n<div><\/div>\r\n<img class=\"aligncenter wp-image-378\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3.png\" alt=\"\" width=\"616\" height=\"190\" \/>\r\n\r\n&nbsp;\r\n\r\n<strong>5\u00a0\u00a0<\/strong><strong>Precipitation Titration: End Point Detection: <\/strong>End point determination in a precipitation titration could be done by four methods\r\n\r\n\u2013\u00a0 Mohr\u2019s Method\r\n\r\n\u2013\u00a0 Volhards Method\r\n\r\n\u2013\u00a0 Fajan\u2019s Method\r\n\r\n\u2013\u00a0 Conductivity Method\r\n\r\n<strong>End Point Indication:<\/strong>\r\n<p style=\"text-align: justify\">Two types of indicators are used to determine the end point in precipitation titrations. One type of indicators are those which form colored compounds when excess amount of titrant is added. Adsorption indicators are the indicators which are adsorbed on the precipitates at equivalence point with change in color on adsorption.<\/p>\r\n<p style=\"text-align: justify\"><em>End point detection with indicators that forms colored compounds with excess titrants<\/em><\/p>\r\n<strong>5.1<\/strong>\u00a0<strong>Mohr\u2019s Method:<\/strong>\r\n<p style=\"text-align: justify\"><em>Direct precipitation titration <\/em>e.g. determination of chloride using silver nitrate in presence of chromate as indicator.<\/p>\r\n<strong>NaCl + AgNO<sub>3<\/sub> <\/strong><strong>\u21c6<\/strong><strong> AgCl (s) + Na<\/strong><strong>+<\/strong><strong> (aq.) + NO<sup>3<\/sup><\/strong><sup><strong>-<\/strong><\/sup><strong> (aq) Ksp = 1.82 x 10<\/strong><strong>-10<\/strong>\r\n\r\n<img class=\"aligncenter size-full wp-image-379\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4.png\" alt=\"\" width=\"524\" height=\"146\" \/>\r\n\r\n<\/div>\r\n<img class=\"aligncenter size-full wp-image-380\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5.png\" alt=\"\" width=\"382\" height=\"78\" \/>\r\n<div>\r\n<p style=\"text-align: justify\">Chromate does not precipitate until Cl- ions have been completely consumed by Ag+ ions owing to solubility product and concentration of chromate in solution. The pH of the solution plays an important role with chromate under acidic conditions undergo a change to dichromate, whereas as pH above 10 silver precipitates as AgOH.<\/p>\r\n<img class=\"aligncenter size-full wp-image-381\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6.png\" alt=\"\" width=\"534\" height=\"159\" \/>\r\n<p style=\"text-align: justify\"><strong>5.2 Volhard\u2019s Method: <\/strong>Indirect Argentometric titration method for halides utilizes the reaction of thiocyanate with Ag+ ions to form precipitate. These titrations are performed in dilute nitric acid as all the silver halides are sparingly soluble in acidic solution. A measured amount of AgNO3 solutions is added to the sample<\/p>\r\n<img class=\"aligncenter size-full wp-image-382\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7.png\" alt=\"\" width=\"517\" height=\"58\" \/>Excess of silver ions determined by back titration with thiocyanate ions in presence of Fe(III) ions as indicator\r\n\r\n<img class=\"aligncenter size-full wp-image-383\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8.png\" alt=\"\" width=\"450\" height=\"131\" \/>\r\n<p style=\"text-align: justify\">For titrations where AgX (I, Br) is less soluble than AgSCN there is no need to remove precipitates before back titration. For AgCl which is more soluble than AgSCN, the AgCl slowly dissolves and is replaced by AgSCN before the reaction of Fe+3 in solution. For this, more amount of titre is required\u00a0<span style=\"font-size: 1em;text-align: initial\">resulting into erroneous result. These errors can be removed by addition of masking agent such as dibutylphthalate.<\/span><\/p>\r\n\r\n<\/div>\r\n<div>\r\n\r\n<em>Adsorption indicators:<\/em>\r\n\r\n<strong>5.3<\/strong>\u00a0<strong>FAJAN\u2019s METHOD:<\/strong>\r\n<p style=\"text-align: justify\">The adsorption indicators are usually anionic dyes which get attached to the positively charged particles that are produced during the titration. The method exploits the surface charge on the colloidal precipitates formed. The dye is adsorbed on the surface of colloid based on the charge on the surface e.g. argentometric titration for estimation of chloride ions.<\/p>\r\n\r\n<ul>\r\n \t<li style=\"text-align: justify\">During the pre-equivalence stage, Cl- ions are more and the crystals of AgCl which ppt. have negative surface charge due the excess of chloride ions.<\/li>\r\n \t<li style=\"text-align: justify\">Upon further titration with Ag+ in the post equivalence stage, the crystals of AgCl have positive charge due to excess of Ag+ ions.<\/li>\r\n \t<li style=\"text-align: justify\">The dye is not adsorbed in the pre equivalence stage thus the solution has yellow color and precipitates are white. However in the post equivalence point the positively colloidal precipitates adsorbs fluoroscein with characteristics red color imparted to the precipitates.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n\r\n<img class=\"aligncenter size-full wp-image-384\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9.png\" alt=\"\" width=\"648\" height=\"459\" \/>\r\n<p style=\"text-align: center\"><strong>Figure 3: Depicting the mechanism of action of Fajan\u2019s indicator for argentometric titrations of chloride ions<\/strong><\/p>\r\n<p style=\"text-align: justify\"><strong>5.4 Conductometric Argentometric Titration: <\/strong>As precipitation reactions involve the removal of ions from solution as salt precipitation leads to lowering of the conductivity of the titre initially.<\/p>\r\n\r\n<ul>\r\n \t<li style=\"text-align: justify\">In pre equivalence stage, chloride gets precipitated as AgCl and the conductivity of the sample decreases<\/li>\r\n \t<li style=\"text-align: justify\">At equivalence point, the chloride ions conductivity of the solution is minimum and is replaced by the bulky nitrate ions.<\/li>\r\n \t<li style=\"text-align: justify\">In post equivalence stage, excess of AgNO3 in solution increases the conductivity of the sample again.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n\r\n<img class=\"aligncenter size-full wp-image-385\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10.png\" alt=\"\" width=\"353\" height=\"341\" \/>\r\n<p style=\"text-align: center\"><strong>Figure 4: The conductometric behavior of argentometric titration of chloride ions<\/strong><\/p>\r\n<strong>6<\/strong>\u00a0\u00a0<strong>Application of Precipitation Titration:<\/strong>\r\n<p style=\"text-align: justify\"><em><strong>6.1 Determination of chloride<\/strong> (mg\/L) in water and wastewater samples at low TDS. <\/em>To a 100 ml water sample to be analyzed in the titre flask, add 5-6 drops of chromate indicator solution. Titrate with 0.0141 N silver nitrate solution to reddish brown end point. Note down the volume of titrant used.<\/p>\r\n<img class=\"aligncenter size-full wp-image-386\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11.png\" alt=\"\" width=\"402\" height=\"107\" \/>\r\n<p style=\"text-align: justify\"><em><strong>6.2 Determination of cyanide<\/strong> (mg\/L) in wastewater from acrylonitrile polymer production unit wastewater. <\/em>CN- containing wastewater is mixed with KI under slightly basic conditions and argentometric titration performed.<\/p>\r\n\u2013 Initially, silver complexes to give silver cyanide complexes Ag+ + CN- \u00e0 Ag(CN)2-\r\n\r\n<\/div>\r\n<div>\r\n\r\n\u2013\u00a0 Excess Ag+ ions react with Iodide forming precipitate\r\n\r\n<em><strong>6.3 Determination of sulphate<\/strong> in water and wastewater, upon precipitation as BaSO<\/em><em>4<\/em><em> using conductometric titration<\/em>\r\n\r\n\u2013 Sulphate ions in a water\/wastewater could be determined by a conductometric titration with BaCl2 solution.\r\n\r\n\u2013 In pre equivalence stage, the sulphate gets precipitated and the conductivity of the sample decreases\r\n\r\n\u2013\u00a0 At equivalence point, the sulphate ions conductivity of the solution is minimum.\r\n\r\n\u2013 In post equivalence stage, excess of BaCl2 in solution increases the conductivity of the sample\r\n\r\n<img class=\"aligncenter size-full wp-image-387\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12.png\" alt=\"\" width=\"361\" height=\"338\" \/>\r\n<p style=\"text-align: center\"><strong>Figure 5: The conductometric behavior of argentometric titration for estimation of suphate in water<\/strong><\/p>\r\n\r\n<table>\r\n<tbody>\r\n<tr>\r\n<td><strong>you can view video on Precipitation(Argentometric) Titrations<\/strong><\/td>\r\n<td><a href=\"https:\/\/youtu.be\/m1mYT2NgTrY\" target=\"_blank\" rel=\"noopener\"><img class=\"alignnone wp-image-120\" src=\"http:\/\/epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/2018\/11\/download.png\" alt=\"\" width=\"36\" height=\"36\" \/><\/a><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n\r\n<strong style=\"font-size: 1em\">Bibliography<\/strong>\r\n\r\n<\/div>\r\n<ol>\r\n \t<li>G. Marr and B.W. Rocket, \u2018Practical Inorganic Chemistry\u2019, University Science Books, <strong>1999.<\/strong><\/li>\r\n \t<li>G. Pass and H. Sutcliffe, \u2018Practical Inorganic Chemistry\u2019, Chapman and Hall, London, <strong>1968<\/strong>.<\/li>\r\n \t<li>Vogel's Textbook of Quantitative Chemical Analysis, Arthur Israel Vogel, Prentice Hall, 2000.<\/li>\r\n \t<li style=\"text-align: justify\">J. Mendham, R. C. Denney, J. D. Barnes, M. Thomas, \u2018Vogel\u2019s Textbook of Quantitative Analysis\u2019, Pearson Education, <strong>2006.<\/strong><\/li>\r\n<\/ol>","rendered":"<div><span style=\"float: right\"><a href=\"https:\/\/youtu.be\/pYNPbUxqJWE\" target=\"_blank\" rel=\"noopener\"><img decoding=\"async\" src=\"http:\/\/epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/2018\/11\/download.png\" alt=\"epgp books\" width=\"75px\" height=\"75px;\" \/><\/a><br \/>\n<\/span><\/div>\n<div>\n<p>&nbsp;<\/p>\n<p>1. What are precipitation reactions?<\/p>\n<p>2. What are solubility product and ionic product?<\/p>\n<p>3. What are the factors effecting solubility?<\/p>\n<p>4. What are argentometric titrations?<\/p>\n<p>5. How is the end point of precipitation titration?<\/p>\n<p>6. What are the applications of precipitation titration?<\/p>\n<\/div>\n<div>\n<p>&nbsp;<\/p>\n<p style=\"text-align: justify\"><strong>1.\u00a0<\/strong><strong>Precipitation Titration: <\/strong>Precipitation titrations involve the stoichiometric reaction of standard precipitating agent with analyte. Precipitation titrations involving the use of silver ion as precipitating agent are classified as argentometric titrations<strong>.<\/strong><\/p>\n<p>&nbsp;<\/p>\n<p><strong>1\u00a0<\/strong><strong>Basic Requirements: <\/strong>The precipitate formed should have a definite stoichiometric.<\/p>\n<p>\u2022 The equilibrium between the precipitate and its ions in solution much be attained rapidly.<\/p>\n<p>\u2022 The precipitate must be of low solubility in the solution i.e., low solubility product.<\/p>\n<p>\u2022\u00a0 Suitable method for the detection of stoichiometric end-point of the titration.<\/p>\n<p>&nbsp;<\/p>\n<p><strong>2\u00a0<\/strong><strong>Solubility Product:<\/strong><\/p>\n<p>What happens when a sparingly soluble salt is put into a solvent?<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-375\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2.png\" alt=\"\" width=\"595\" height=\"200\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2.png 595w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-300x101.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-65x22.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-225x76.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-350x118.png 350w\" sizes=\"auto, (max-width: 595px) 100vw, 595px\" \/><\/p>\n<p style=\"text-align: center\"><strong>Figure 1: Stages of dissolution of salt<\/strong><\/p>\n<p>An equilibrium exists between a partially soluble substance and its solution<\/p>\n<table class=\"aligncenter\" style=\"width: 60%\">\n<tbody>\n<tr>\n<td>For Example<\/td>\n<td><\/td>\n<\/tr>\n<tr>\n<td>BaSO<sub>4<\/sub> (s)<strong>\u21cc<\/strong><\/td>\n<td>Ba<sup>2+<\/sup> (aq) + SO<sub>4<\/sub><sup>2-<\/sup> (aq)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>K\u00a0 = [Ba<sup>2+<\/sup> (aq)][SO4<sup>2-<\/sup> (aq)] \/ [BaSO<sub>4<\/sub>(s)] K = K<em>sp<\/em>, the solubility-product constant, as [BaSO<sub>4<\/sub> (s)] = unity<\/p>\n<p><span style=\"font-size: 1em;text-align: initial\">K<\/span><em style=\"font-size: 1em;text-align: initial\">sp<\/em><span style=\"font-size: 1em;text-align: initial\"> = [Ba<sup>2+<\/sup>(aq)][SO<sub>4<\/sub><sup>2-<\/sup>(aq)]<\/span><\/p>\n<\/div>\n<div>\n<p style=\"text-align: justify\">Thus, Solubility Product (K<em>sp<\/em>) is defined as equilibrium constant for the equilibrium between an ionic solid and its saturated solution.<\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: justify\"><strong>2.1<\/strong>\u00a0<em>General Expression for Solubility Product:<\/em><\/p>\n<p style=\"text-align: justify\">AaBb(s) aAb+ (aq) + bBa- (aq)<\/p>\n<p style=\"text-align: justify\">K<em>sp<\/em> = <strong>[A<\/strong><strong>b+<\/strong><strong>]<\/strong><strong>a<\/strong> <strong>[B<\/strong><strong>a-<\/strong><strong>]<\/strong><strong>b<\/strong><\/p>\n<p style=\"text-align: justify\">Example: PbI2 (s)\u00a0 Pb2+ + 2 I-K<em>sp<\/em> = [Pb2+] [I-]2<\/p>\n<p style=\"text-align: justify\">Higher Ksp indicates high molar solubility; whereas lower Ksp indicates low molar solubility of the salt e.g. AgCl has lower solubility than NaCl.<\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: justify\"><strong>3\u00a0<\/strong><strong>Conditions for Precipitation:<\/strong><\/p>\n<ul>\n<li style=\"text-align: justify\">\u00a0Precipitation is reverse of the dissolution phenomenon<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p style=\"text-align: justify\"><strong>3.1 Ionic Product: <\/strong>ionic product is the term given for the product of the concentration of cation and anion raised to the power of their respective stoichiometry in the salt.<\/p>\n<ul>\n<li style=\"text-align: justify\">Ionic product is the evaluation of the strength of ions under non-equilibrium condition. e.g. Ionic Product of BaCl2 would be given by Q<em>sp<\/em> = [Ba2+(aq)][Cl-(aq)]2<\/li>\n<li><em>Q<\/em>sp =<em> K<\/em>sp \u00e8 saturated solution, but no precipitate<\/li>\n<li>Qsp &gt; Ksp \u00e8 saturated solution, with precipitate<\/li>\n<li><em style=\"text-align: initial;font-size: 1em\">Q<\/em><span style=\"text-align: initial;font-size: 1em\">sp &lt;<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">sp \u00e8 unsaturated solution,<\/span><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p><strong>3.2<\/strong>\u00a0<strong>Factors Affecting Solubility \/ Precipitation<\/strong><\/p>\n<p>\u2022\u00a0 Temperature<\/p>\n<p>\u2022\u00a0 Common ion effect<\/p>\n<p>\u2022\u00a0 Salt effect<\/p>\n<p>\u2022\u00a0 pH of solution<\/p>\n<p>\u2022\u00a0 Formation of complex ion<\/p>\n<p><strong>3.2.1<\/strong>\u00a0\u00a0\u00a0\u00a0 <strong>Common Ion Effect<\/strong><\/p>\n<p>\u2022\u00a0 Consider the following solubility equilibrium:<\/p>\n<p><span style=\"font-size: 1em;text-align: initial\">AgCl(s) <\/span><strong style=\"font-size: 1em;text-align: initial\">\u21cc<\/strong><span style=\"font-size: 1em;text-align: initial\"> Ag+(aq) + Cl-(aq); <\/span><em style=\"font-size: 1em;text-align: initial\">K<\/em><span style=\"font-size: 1em;text-align: initial\">sp = 1.6 x 10-10<\/span><\/p>\n<\/div>\n<div>\n<p>\u2022\u00a0 The solubility of AgCl is 1.3 x 10-5 mol\/L at 25oC.<\/p>\n<p style=\"text-align: justify\">\u2022\u00a0 If NaCl is added, equilibrium shifts left due to increase in [Cl<sup>&#8211;<\/sup>] and more AgCl will precipitate out. For example, if [Cl-] = 1.0 x 10-2 M,<\/p>\n<p style=\"text-align: justify\">\u2022\u00a0 Solubility of AgCl = (1.6 x 10-10)\/(1.0 x 10-2)=\u00a0 1.6 x 10-8 mol\/L<\/p>\n<p>&nbsp;<\/p>\n<p><strong>3.2.2\u00a0\u00a0\u00a0 Effect of pH on Solubility<\/strong><\/p>\n<ul>\n<li>Consider the following equilibrium: Ag3PO4(s) <strong>\u21cc<\/strong> 3Ag+(aq) + PO43-(aq);<\/li>\n<li>\u00a0If HNO3 is added, the following reaction occurs: H3O+(aq) + PO43-(aq) <strong>\u21cc<\/strong> HPO42-(aq) + H2O<\/li>\n<li><span style=\"text-align: initial;font-size: 1em\">Consider the following equilibrium: Mg(OH)2(s) <\/span><strong style=\"text-align: initial;font-size: 1em\">\u21cc<\/strong><span style=\"text-align: initial;font-size: 1em\"> Mg2+(aq) + 2 OH-(aq);<\/span><\/li>\n<li>\u00a0Increasing the pH means increasing [OH-] and equilibrium will shift to the left, causing some of Mg(OH)2 to precipitate out.<\/li>\n<\/ul>\n<p><strong>3.2.3\u00a0\u00a0\u00a0 Formation of Complex Ions on Solubility<\/strong><\/p>\n<ul>\n<li>Many transition metals ions have strong affinity for ligands to form complex ions.<\/li>\n<li>Ligands are molecules, such as H2O, NH3 and CO, or anions, such as F-, CN- and S2O32-.<\/li>\n<li>Complexes are soluble \u2013 thus, the formation of complex ions increases solubility of slightly soluble ionic compounds.<\/li>\n<li>Consider the following equilibria:<\/li>\n<li>Combining the two equations yields:AgCl(s) + 2NH<sub>3<\/sub>(aq) <strong style=\"text-align: initial;font-size: 1em\">\u21cc<\/strong><span style=\"text-align: initial;font-size: 1em\"> Ag(NH<sub>3<\/sub>)<sup>2+<\/sup>(aq) + Cl-(aq);\u00a0<\/span><em style=\"text-align: initial;font-size: 1em\">K<\/em><span style=\"text-align: initial;font-size: 1em\">net =<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">sp x<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">f = (1.6 x 10<sup>-10<\/sup>) x (1.7 x 10<sup>7<\/sup>)<\/span>=\u00a0 <strong style=\"text-align: initial;font-size: 1em\">2.7 x 10<\/strong><strong style=\"text-align: initial;font-size: 1em\">-3<\/strong><\/li>\n<li><em style=\"text-align: initial;font-size: 1em\">K<\/em><span style=\"text-align: initial;font-size: 1em\">net &gt;<\/span><em style=\"text-align: initial;font-size: 1em\"> K<\/em><span style=\"text-align: initial;font-size: 1em\">sp implies that AgCl is more soluble in aqueous NH<sub>3<\/sub> than in water.<\/span><\/li>\n<li>Consider the following case: 20.0 mL of 0.025 M Pb(NO3)2 is added to 30.0 mL of 0.10 M NaCl. Predict if precipitate of PbCl2 will form. (<em style=\"text-align: initial;font-size: 1em\">Ksp<\/em><span style=\"text-align: initial;font-size: 1em\"> for PbCl2 = 1.6 x 10-5)<\/span><\/li>\n<\/ul>\n<\/div>\n<div>\n<p>Calculation:<\/p>\n<p>[Pb<sup>2+<\/sup>] = (20.0 mL x 0.025 M)\/(50.0 mL) = 0.010 M<\/p>\n<p>[Cl<sup>&#8211;<\/sup>] = (30.0 mL x 0.10 M)\/(50.0 mL) = 0.060 M<\/p>\n<p><em>Q<\/em>sp = [Pb<sup>2+<\/sup>][Cl<sup>&#8211;<\/sup>]<sup>2<\/sup> = (0.010 M)(0.060 M)2<em>\u00a0 <\/em>= 3.6 x 10-5<\/p>\n<p><strong><em>Q<\/em><\/strong><strong>sp<\/strong> <strong>&gt;<em> K<\/em><\/strong><strong>sp<\/strong><strong><em>\u00a0 <\/em><\/strong><strong>\u00e8<\/strong> <strong>precipitate of PbCl<\/strong><strong>2<\/strong> <strong>will form.<\/strong><\/p>\n<p style=\"text-align: justify\"><strong>4\u00a0<\/strong><strong>Argentometric Titration: <\/strong>Argentometric titration is carried out by addition of standardized AgNO3 solution to the analyte solution.Upon increasing the concentration of AgNO3 in the titre to an extent that the ionic product of Ag+ and Cl- exceeds the solubility product, a suspension is formed. This increase in the titrant leads to depletion of titre and increase in the \u2013log10 [Cl-]. The titration curve is normally broken down in three regions for the purposes of calculation and a function for pCl is determined for each region:<\/p>\n<p><strong>4.1 <\/strong>Pre-equivalence region<\/p>\n<p><strong>4.2 <\/strong>Equivalence point<\/p>\n<p><strong>4.3 <\/strong>Post-equivalence region<\/p>\n<\/div>\n<div>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-376\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1.png\" alt=\"\" width=\"351\" height=\"348\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1.png 351w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1-150x150.png 150w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1-300x297.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1-65x64.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1-225x223.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-1-350x347.png 350w\" sizes=\"auto, (max-width: 351px) 100vw, 351px\" \/><\/p>\n<p style=\"text-align: center\"><strong>Figure 2:<\/strong>\u00a0\u00a0\u00a0\u00a0 <strong>The precipitation titration response curve for argentometric titration of chloride ions\u00a0<\/strong><strong>Argentometric Titration:<\/strong><\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-377\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2.png\" alt=\"\" width=\"517\" height=\"303\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2.png 517w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2-300x176.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2-65x38.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2-225x132.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-2-350x205.png 350w\" sizes=\"auto, (max-width: 517px) 100vw, 517px\" \/><strong>Table 1: The progress of argentometric titration for chloride ions Calculation at S. No. 2: 10.00 mL Titrant Added (Pre-equivalence Region)<\/strong><\/p>\n<p>mmol Cl<sup>&#8211;<\/sup> started = 25.00 mL 0.100 M = 2.50 mmol<\/p>\n<\/div>\n<div>\n<div><\/div>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-378\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3.png\" alt=\"\" width=\"616\" height=\"190\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3.png 548w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3-300x93.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3-65x20.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3-225x69.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-3-350x108.png 350w\" sizes=\"auto, (max-width: 616px) 100vw, 616px\" \/><\/p>\n<p>&nbsp;<\/p>\n<p><strong>5\u00a0\u00a0<\/strong><strong>Precipitation Titration: End Point Detection: <\/strong>End point determination in a precipitation titration could be done by four methods<\/p>\n<p>\u2013\u00a0 Mohr\u2019s Method<\/p>\n<p>\u2013\u00a0 Volhards Method<\/p>\n<p>\u2013\u00a0 Fajan\u2019s Method<\/p>\n<p>\u2013\u00a0 Conductivity Method<\/p>\n<p><strong>End Point Indication:<\/strong><\/p>\n<p style=\"text-align: justify\">Two types of indicators are used to determine the end point in precipitation titrations. One type of indicators are those which form colored compounds when excess amount of titrant is added. Adsorption indicators are the indicators which are adsorbed on the precipitates at equivalence point with change in color on adsorption.<\/p>\n<p style=\"text-align: justify\"><em>End point detection with indicators that forms colored compounds with excess titrants<\/em><\/p>\n<p><strong>5.1<\/strong>\u00a0<strong>Mohr\u2019s Method:<\/strong><\/p>\n<p style=\"text-align: justify\"><em>Direct precipitation titration <\/em>e.g. determination of chloride using silver nitrate in presence of chromate as indicator.<\/p>\n<p><strong>NaCl + AgNO<sub>3<\/sub> <\/strong><strong>\u21c6<\/strong><strong> AgCl (s) + Na<\/strong><strong>+<\/strong><strong> (aq.) + NO<sup>3<\/sup><\/strong><sup><strong>&#8211;<\/strong><\/sup><strong> (aq) Ksp = 1.82 x 10<\/strong><strong>-10<\/strong><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-379\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4.png\" alt=\"\" width=\"524\" height=\"146\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4.png 524w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4-300x84.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4-65x18.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4-225x63.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-4-350x98.png 350w\" sizes=\"auto, (max-width: 524px) 100vw, 524px\" \/><\/p>\n<\/div>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-380\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5.png\" alt=\"\" width=\"382\" height=\"78\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5.png 382w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5-300x61.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5-65x13.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5-225x46.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-5-350x71.png 350w\" sizes=\"auto, (max-width: 382px) 100vw, 382px\" \/><\/p>\n<div>\n<p style=\"text-align: justify\">Chromate does not precipitate until Cl- ions have been completely consumed by Ag+ ions owing to solubility product and concentration of chromate in solution. The pH of the solution plays an important role with chromate under acidic conditions undergo a change to dichromate, whereas as pH above 10 silver precipitates as AgOH.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-381\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6.png\" alt=\"\" width=\"534\" height=\"159\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6.png 534w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6-300x89.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6-65x19.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6-225x67.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-6-350x104.png 350w\" sizes=\"auto, (max-width: 534px) 100vw, 534px\" \/><\/p>\n<p style=\"text-align: justify\"><strong>5.2 Volhard\u2019s Method: <\/strong>Indirect Argentometric titration method for halides utilizes the reaction of thiocyanate with Ag+ ions to form precipitate. These titrations are performed in dilute nitric acid as all the silver halides are sparingly soluble in acidic solution. A measured amount of AgNO3 solutions is added to the sample<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-382\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7.png\" alt=\"\" width=\"517\" height=\"58\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7.png 517w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7-300x34.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7-65x7.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7-225x25.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-7-350x39.png 350w\" sizes=\"auto, (max-width: 517px) 100vw, 517px\" \/>Excess of silver ions determined by back titration with thiocyanate ions in presence of Fe(III) ions as indicator<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-383\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8.png\" alt=\"\" width=\"450\" height=\"131\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8.png 450w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8-300x87.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8-65x19.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8-225x66.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-8-350x102.png 350w\" sizes=\"auto, (max-width: 450px) 100vw, 450px\" \/><\/p>\n<p style=\"text-align: justify\">For titrations where AgX (I, Br) is less soluble than AgSCN there is no need to remove precipitates before back titration. For AgCl which is more soluble than AgSCN, the AgCl slowly dissolves and is replaced by AgSCN before the reaction of Fe+3 in solution. For this, more amount of titre is required\u00a0<span style=\"font-size: 1em;text-align: initial\">resulting into erroneous result. These errors can be removed by addition of masking agent such as dibutylphthalate.<\/span><\/p>\n<\/div>\n<div>\n<p><em>Adsorption indicators:<\/em><\/p>\n<p><strong>5.3<\/strong>\u00a0<strong>FAJAN\u2019s METHOD:<\/strong><\/p>\n<p style=\"text-align: justify\">The adsorption indicators are usually anionic dyes which get attached to the positively charged particles that are produced during the titration. The method exploits the surface charge on the colloidal precipitates formed. The dye is adsorbed on the surface of colloid based on the charge on the surface e.g. argentometric titration for estimation of chloride ions.<\/p>\n<ul>\n<li style=\"text-align: justify\">During the pre-equivalence stage, Cl- ions are more and the crystals of AgCl which ppt. have negative surface charge due the excess of chloride ions.<\/li>\n<li style=\"text-align: justify\">Upon further titration with Ag+ in the post equivalence stage, the crystals of AgCl have positive charge due to excess of Ag+ ions.<\/li>\n<li style=\"text-align: justify\">The dye is not adsorbed in the pre equivalence stage thus the solution has yellow color and precipitates are white. However in the post equivalence point the positively colloidal precipitates adsorbs fluoroscein with characteristics red color imparted to the precipitates.<\/li>\n<\/ul>\n<\/div>\n<div>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-384\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9.png\" alt=\"\" width=\"648\" height=\"459\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9.png 648w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9-300x213.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9-65x46.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9-225x159.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-9-350x248.png 350w\" sizes=\"auto, (max-width: 648px) 100vw, 648px\" \/><\/p>\n<p style=\"text-align: center\"><strong>Figure 3: Depicting the mechanism of action of Fajan\u2019s indicator for argentometric titrations of chloride ions<\/strong><\/p>\n<p style=\"text-align: justify\"><strong>5.4 Conductometric Argentometric Titration: <\/strong>As precipitation reactions involve the removal of ions from solution as salt precipitation leads to lowering of the conductivity of the titre initially.<\/p>\n<ul>\n<li style=\"text-align: justify\">In pre equivalence stage, chloride gets precipitated as AgCl and the conductivity of the sample decreases<\/li>\n<li style=\"text-align: justify\">At equivalence point, the chloride ions conductivity of the solution is minimum and is replaced by the bulky nitrate ions.<\/li>\n<li style=\"text-align: justify\">In post equivalence stage, excess of AgNO3 in solution increases the conductivity of the sample again.<\/li>\n<\/ul>\n<\/div>\n<div>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-385\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10.png\" alt=\"\" width=\"353\" height=\"341\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10.png 353w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10-300x290.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10-65x63.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10-225x217.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-10-350x338.png 350w\" sizes=\"auto, (max-width: 353px) 100vw, 353px\" \/><\/p>\n<p style=\"text-align: center\"><strong>Figure 4: The conductometric behavior of argentometric titration of chloride ions<\/strong><\/p>\n<p><strong>6<\/strong>\u00a0\u00a0<strong>Application of Precipitation Titration:<\/strong><\/p>\n<p style=\"text-align: justify\"><em><strong>6.1 Determination of chloride<\/strong> (mg\/L) in water and wastewater samples at low TDS. <\/em>To a 100 ml water sample to be analyzed in the titre flask, add 5-6 drops of chromate indicator solution. Titrate with 0.0141 N silver nitrate solution to reddish brown end point. Note down the volume of titrant used.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-386\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11.png\" alt=\"\" width=\"402\" height=\"107\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11.png 402w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11-300x80.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11-65x17.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11-225x60.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-11-350x93.png 350w\" sizes=\"auto, (max-width: 402px) 100vw, 402px\" \/><\/p>\n<p style=\"text-align: justify\"><em><strong>6.2 Determination of cyanide<\/strong> (mg\/L) in wastewater from acrylonitrile polymer production unit wastewater. <\/em>CN- containing wastewater is mixed with KI under slightly basic conditions and argentometric titration performed.<\/p>\n<p>\u2013 Initially, silver complexes to give silver cyanide complexes Ag+ + CN- \u00e0 Ag(CN)2-<\/p>\n<\/div>\n<div>\n<p>\u2013\u00a0 Excess Ag+ ions react with Iodide forming precipitate<\/p>\n<p><em><strong>6.3 Determination of sulphate<\/strong> in water and wastewater, upon precipitation as BaSO<\/em><em>4<\/em><em> using conductometric titration<\/em><\/p>\n<p>\u2013 Sulphate ions in a water\/wastewater could be determined by a conductometric titration with BaCl2 solution.<\/p>\n<p>\u2013 In pre equivalence stage, the sulphate gets precipitated and the conductivity of the sample decreases<\/p>\n<p>\u2013\u00a0 At equivalence point, the sulphate ions conductivity of the solution is minimum.<\/p>\n<p>\u2013 In post equivalence stage, excess of BaCl2 in solution increases the conductivity of the sample<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-387\" src=\"http:\/\/esp02.epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12.png\" alt=\"\" width=\"361\" height=\"338\" srcset=\"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12.png 361w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12-300x281.png 300w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12-65x61.png 65w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12-225x211.png 225w, https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-content\/uploads\/sites\/163\/2019\/04\/2-12-350x328.png 350w\" sizes=\"auto, (max-width: 361px) 100vw, 361px\" \/><\/p>\n<p style=\"text-align: center\"><strong>Figure 5: The conductometric behavior of argentometric titration for estimation of suphate in water<\/strong><\/p>\n<table>\n<tbody>\n<tr>\n<td><strong>you can view video on Precipitation(Argentometric) Titrations<\/strong><\/td>\n<td><a href=\"https:\/\/youtu.be\/m1mYT2NgTrY\" target=\"_blank\" rel=\"noopener\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-120\" src=\"http:\/\/epgpbooks.inflibnet.ac.in\/wp-content\/uploads\/2018\/11\/download.png\" alt=\"\" width=\"36\" height=\"36\" \/><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong style=\"font-size: 1em\">Bibliography<\/strong><\/p>\n<\/div>\n<ol>\n<li>G. Marr and B.W. Rocket, \u2018Practical Inorganic Chemistry\u2019, University Science Books, <strong>1999.<\/strong><\/li>\n<li>G. Pass and H. Sutcliffe, \u2018Practical Inorganic Chemistry\u2019, Chapman and Hall, London, <strong>1968<\/strong>.<\/li>\n<li>Vogel&#8217;s Textbook of Quantitative Chemical Analysis, Arthur Israel Vogel, Prentice Hall, 2000.<\/li>\n<li style=\"text-align: justify\">J. Mendham, R. C. Denney, J. D. Barnes, M. Thomas, \u2018Vogel\u2019s Textbook of Quantitative Analysis\u2019, Pearson Education, <strong>2006.<\/strong><\/li>\n<\/ol>\n","protected":false},"author":3,"menu_order":27,"template":"","meta":{"_acf_changed":false,"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-371","chapter","type-chapter","status-publish","hentry"],"part":3,"_links":{"self":[{"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/chapters\/371","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/wp\/v2\/users\/3"}],"version-history":[{"count":5,"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/chapters\/371\/revisions"}],"predecessor-version":[{"id":389,"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/chapters\/371\/revisions\/389"}],"part":[{"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/parts\/3"}],"metadata":[{"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/chapters\/371\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/wp\/v2\/media?parent=371"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/pressbooks\/v2\/chapter-type?post=371"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/wp\/v2\/contributor?post=371"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/ebooks.inflibnet.ac.in\/esp02\/wp-json\/wp\/v2\/license?post=371"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}