{"id":1443,"date":"2018-04-11T22:51:57","date_gmt":"2018-04-12T02:51:57","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/chapter\/4-5-quantitative-chemical-analysis\/"},"modified":"2018-06-23T00:00:00","modified_gmt":"2018-06-23T04:00:00","slug":"4-5-quantitative-chemical-analysis","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/chapter\/4-5-quantitative-chemical-analysis\/","title":{"raw":"7.5 Quantitative Chemical Analysis","rendered":"7.5 Quantitative Chemical Analysis"},"content":{"raw":"<div class=\"bcc-box bcc-highlight\">\r\n<h3>Learning Objectives<\/h3>\r\nBy the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Describe the fundamental aspects of titrations and gravimetric analysis.<\/li>\r\n \t<li>Perform stoichiometric calculations using typical titration and gravimetric data.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<p id=\"fs-idp138930544\">In the 18th century, the strength (actually the concentration) of vinegar samples was determined by noting the amount of potassium carbonate, K<sub>2<\/sub>CO<sub>3<\/sub>, which had to be added, a little at a time, before bubbling ceased. The greater the weight of potassium carbonate added to reach the point where the bubbling ended, the more concentrated the vinegar.<\/p>\r\n<p id=\"fs-idm17525264\">We now know that the effervescence that occurred during this process was due to reaction with acetic acid, CH<sub>3<\/sub>CO<sub>2<\/sub>H, the compound primarily responsible for the odor and taste of vinegar. Acetic acid reacts with potassium carbonate according to the following equation:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idm1518128\" style=\"text-align: center\">$latex 2\\text{CH}_3 \\text{CO}_2 \\text{H}(aq) + \\text{K}_2\\text{CO}_3(s) \\longrightarrow \\text{KCH}_3 \\text{CO}_3(aq) + \\text{CO}_2(g) + \\text{H}_2 \\text{O}(l)$<\/div>\r\n<p id=\"fs-idp89786672\">The bubbling was due to the production of CO<sub>2<\/sub>.<\/p>\r\n<p id=\"fs-idp55621088\">The test of vinegar with potassium carbonate is one type of <strong>quantitative analysis<\/strong>\u2014the determination of the amount or concentration of a substance in a sample. In the analysis of vinegar, the concentration of the solute (acetic acid) was determined from the amount of reactant that combined with the solute present in a known volume of the solution. In other types of chemical analyses, the amount of a substance present in a sample is determined by measuring the amount of product that results.<\/p>\r\n\r\n<section id=\"fs-idp85215712\">\r\n<h2>Titration<\/h2>\r\n<p id=\"fs-idp43277952\">The described approach to measuring vinegar strength was an early version of the analytical technique known as <strong>titration analysis<\/strong>. A typical titration analysis involves the use of a <strong>buret<\/strong> (<a href=\"#CNX_Chem_04_05_titration\" class=\"autogenerated-content\">Figure 1<\/a>) to make incremental additions of a solution containing a known concentration of some substance (the <strong>titrant<\/strong>) to a sample solution containing the substance whose concentration is to be measured (the <strong>analyte<\/strong>). The titrant and analyte undergo a chemical reaction of known stoichiometry, and so measuring the volume of titrant solution required for complete reaction with the analyte (the <strong>equivalence point<\/strong> of the titration) allows calculation of the analyte concentration. The equivalence point of a titration may be detected visually if a distinct change in the appearance of the sample solution accompanies the completion of the reaction. The halt of bubble formation in the classic vinegar analysis is one such example, though, more commonly, special dyes called <strong>indicators<\/strong> are added to the sample solutions to impart a change in color at or very near the equivalence point of the titration. Equivalence points may also be detected by measuring some solution property that changes in a predictable way during the course of the titration. Regardless of the approach taken to detect a titration\u2019s equivalence point, the volume of titrant actually measured is called the <strong>end point<\/strong>. Properly designed titration methods typically ensure that the difference between the equivalence and end points is negligible. Though any type of chemical reaction may serve as the basis for a titration analysis, the three described in this chapter (precipitation, acid-base, and redox) are most common. Additional details regarding titration analysis are provided in the chapter on acid-base equilibria.<\/p>\r\n\r\n<figure id=\"CNX_Chem_04_05_titration\"><figcaption>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"527\"]<a href=\"https:\/\/opentextbc.ca\/chemistry\/wp-content\/uploads\/sites\/150\/2016\/05\/CNX_Chem_04_05_titration.jpg\"><img src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_titration-2.jpg\" alt=\"Two pictures are shown. In a, a person is shown pouring a liquid from a small beaker into a buret. The person is wearing goggles and gloves as she transfers the solution into the buret. In b, a close up view of the markings on the side of the buret is shown. The markings for 10, 15, and 20 are clearly shown with horizontal rings printed on the buret. Between each of these whole number markings, half markings are also clearly shown with horizontal line segment markings.\" width=\"527\" height=\"405\" class=\"\" \/><\/a> <strong>Figure 1.<\/strong> (a) A student fills a buret in preparation for a titration analysis. (b) A typical buret permits volume measurements to the nearest 0.1 mL. (credit a: modification of work by Mark Blaser and Matt Evans; credit b: modification of work by Mark Blaser and Matt Evans)[\/caption]\r\n\r\n<\/figcaption><\/figure>\r\n<div class=\"textbox shaded\" id=\"fs-idp80717680\">\r\n<h3>Example 1<\/h3>\r\n<p id=\"fs-idp32280496\">The end point in a titration of a 50.00-mL sample of aqueous HCl was reached by addition of 35.23 mL of 0.250 M NaOH titrant. The titration reaction is:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idp79702544\">\r\n<p style=\"text-align: center\">$latex \\text{HCl}(aq) + \\text{NaOH}(aq) \\longrightarrow \\text{NaCl}(aq) + \\text{H}_2\\text{O}(l)$<\/p>\r\n\r\n<\/div>\r\n<p id=\"fs-idp86323376\">What is the molarity of the HCl?<\/p>\r\n&nbsp;\r\n<p id=\"fs-idm12137328\"><strong>Solution<\/strong><\/p>\r\nAs for all reaction stoichiometry calculations, the key issue is the relation between the molar amounts of the chemical species of interest as depicted in the balanced chemical equation. The approach outlined in previous modules of this chapter is followed, with additional considerations required, since the amounts of reactants provided and requested are expressed as solution concentrations.\r\n<p id=\"fs-idp64054640\">For this exercise, the calculation will follow the following outlined steps:<\/p>\r\n<img src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_map7_img-2.jpg\" alt=\"This figure shows four rectangles. The first is shaded lavender and is labeled, \u201cVolume of N a O H.\u201d This rectangle is followed by an arrow pointing right which is labeled, \u201cMolar concentration,\u201d to a second rectangle. This second rectangle is shaded pink and is labeled, \u201cMoles of N a O H.\u201d This rectangle is followed by an arrow pointing right which is labeled, \u201cStoichiometric factor,\u201d to a third rectangle which is shaded pink and is labeled, \u201cMoles of H C l.\u201d This rectangle is followed by an arrow labeled, \u201cSolution volume,\u201d which points right to a fourth rectangle. This fourth rectangle is shaded lavender and is labeled, \u201cConcentration of H C l.\u201d\" width=\"533\" height=\"237\" class=\"aligncenter\" \/>\r\n<p id=\"fs-idp137498176\">The molar amount of HCl is calculated to be:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idp60191360\" style=\"text-align: center\">$latex 35.23 \\;\\rule[0.5ex]{4.5em}{0.1ex}\\hspace{-4.5em}\\text{mL NaOH} \\times \\frac{1 \\;\\rule[0.25ex]{0.5em}{0.1ex}\\hspace{-0.5em}\\text{L}}{1000 \\rule[0.25ex]{1.25em}{0.1ex}\\hspace{-1.25em}\\;\\text{mL}} \\times \\frac{0.250 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol NaOH}}{1 \\;\\rule[0.25ex]{0.5em}{0.1ex}\\hspace{-0.5em}\\text{L}} \\times \\frac{1 \\;\\text{mol HCl}}{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol NaOH}} = \\underline{8.80}75 \\times 10^{-3} \\;\\text{mol HCl with 3 sig figs}$<\/div>\r\n<p id=\"fs-idp18819536\">Using the provided volume of HCl solution and the definition of molarity, the HCl concentration is:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idp180416144\" style=\"text-align: center\">$latex \\begin{array}{r @{{}={}} l} M &amp; \\frac{\\text{mol HCl}}{\\text{L solution}} \\\\[1em] M &amp; \\frac{\\underline{8.80}75 \\times 10^{-3} \\;\\text{mol HCl}}{50.00 \\;\\text{mL} \\times \\frac{1 \\;\\text{L}}{1000 \\;\\text{mL}}} \\\\[1em] M &amp; 0.176 \\;M \\end{array}$<\/div>\r\n<p id=\"fs-idp24080800\">Note: For these types of titration calculations, it is convenient to recognize that solution molarity is also equal to the number of <em>milli<\/em>moles of solute per <em>milli<\/em>liter of solution:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idm39309120\" style=\"text-align: center\">$latex M = \\frac{\\text{mol solute}}{\\text{L solution}} \\times \\frac{\\frac{10^3 \\;\\text{mmol}}{\\text{mol}}}{\\frac{10^3 \\;\\text{mL}}{\\text{L}}} = \\frac{\\text{mmol solute}}{\\text{mL solution}}$<\/div>\r\n<p id=\"fs-idm35999792\">Using this version of the molarity unit will shorten the calculation by eliminating two conversion factors:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idm27436528\">\r\n<p style=\"text-align: center\">$latex \\frac{35.23 \\;\\text{mL NaOH} \\times \\;\\frac{0.250 \\;\\text{mmol NaOH}}{\\text{mL NaOH}} \\times \\frac{1 \\;\\text{mmol HCl}}{1 \\;\\text{mmol NaOH}}}{50.00 \\;\\text{mL solution}} = 0.176 \\;M \\;\\text{HCl}$<\/p>\r\n\r\n<\/div>\r\n&nbsp;\r\n<p id=\"fs-idm12966032\"><em><strong>Test Yourself<\/strong><\/em>\r\nA 20.00-mL sample of aqueous oxalic acid, H<sub>2<\/sub>C<sub>2<\/sub>O<sub>4<\/sub>, was titrated with a 0.09113-<em>M<\/em> solution of potassium permanganate.<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idm30080224\" style=\"text-align: center\">$latex {2\\text{MnO}_4}^{-}(aq) + 5\\text{H}_2 \\text{C}_2 \\text{O}_4(aq) + 6\\text{H}^{+}(aq) \\longrightarrow 10\\text{CO}_2(g) + 2\\text{Mn}^{2+}(aq) + 8\\text{H}_2 \\text{O}(l)$<\/div>\r\n<p id=\"fs-idm46826912\">A volume of 23.24 mL was required to reach the end point. What is the oxalic acid molarity?<\/p>\r\n&nbsp;\r\n\r\n<em><strong>Answer<\/strong><\/em>\r\n\r\n0.2648 M\r\n\r\n<\/div>\r\n<\/section><section id=\"fs-idp68434144\">\r\n<h2>Gravimetric Analysis<\/h2>\r\n<p id=\"fs-idp27521328\">A <strong>gravimetric analysis<\/strong> is one in which a sample is subjected to some treatment that causes a change in the physical state of the analyte that permits its separation from the other components of the sample. Mass measurements of the sample, the isolated analyte, or some other component of the analysis system, used along with the known stoichiometry of the compounds involved, permit calculation of the analyte concentration. Gravimetric methods were the first techniques used for quantitative chemical analysis, and they remain important tools in the modern chemistry laboratory.<\/p>\r\nThe required change of state in a gravimetric analysis may be achieved by various physical and chemical processes. For example, the moisture (water) content of a sample is routinely determined by measuring the mass of a sample before and after it is subjected to a controlled heating process that evaporates the water. Also common are gravimetric techniques in which the analyte is subjected to a precipitation reaction of the sort described earlier in this chapter. The precipitate is typically isolated from the reaction mixture by filtration, carefully dried, and then weighed (<a href=\"#CNX_Chem_04_05_Filter\" class=\"autogenerated-content\">Figure 2<\/a>). The mass of the precipitate may then be used, along with relevant stoichiometric relationships, to calculate analyte concentration.\r\n\r\n<\/section><section id=\"fs-idp68434144\">\r\n<figure id=\"CNX_Chem_04_05_Filter\">\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"217\"]<a href=\"https:\/\/opentextbc.ca\/chemistry\/wp-content\/uploads\/sites\/150\/2016\/05\/CNX_Chem_04_05_filter.jpg\"><img src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_filter-2.jpg\" alt=\"A photo is shown of a flask and funnel used for filtration. The flask contains a slightly opaque liquid filtrate with a slight yellow tint. A funnel, which contains a bright yellow and orange material, sits atop the flask. The flask is held in place by a clamp and is connected to a vacuum line. The connection between the funnel and flask is sealed with a rubber bung or gasket.\" width=\"217\" height=\"351\" class=\"\" \/><\/a> <strong>Figure 2.<\/strong> Precipitate may be removed from a reaction mixture by filtration.[\/caption]<\/figure>\r\n<\/section><section id=\"fs-idp68434144\">\r\n<div class=\"textbox shaded\" id=\"fs-idp69077568\">\r\n<h3>Example 2<\/h3>\r\nA 0.4550-g solid mixture containing MgSO<sub>4<\/sub> is dissolved in water and treated with an excess of Ba(NO<sub>3<\/sub>)<sub>2<\/sub>, resulting in the precipitation of 0.6168 g of BaSO<sub>4<\/sub>.\r\n<div class=\"equation\" id=\"fs-idm25559056\" style=\"text-align: center\">$latex \\text{MgSO}_4(aq) + \\text{Ba(NO}_3)_2(aq) \\longrightarrow \\text{BaSO}_4(s) + \\text{Mg(NO}_3)_2(aq)$<\/div>\r\n<p id=\"fs-idp114808768\">What is the concentration (percent) of MgSO<sub>4<\/sub> in the mixture?<\/p>\r\n&nbsp;\r\n<p id=\"fs-idp87548576\"><strong>Solution<\/strong><\/p>\r\nThe plan for this calculation is similar to others used in stoichiometric calculations, the central step being the connection between the moles of BaSO<sub>4<\/sub> and MgSO<sub>4<\/sub> through their stoichiometric factor. Once the mass of MgSO<sub>4<\/sub> is computed, it may be used along with the mass of the sample mixture to calculate the requested percentage concentration.\r\n\r\n<img src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_map8_img-2.jpg\" alt=\"This figure shows five rectangles. The first is shaded yellow and is labeled \u201cMass of B a S O subscript 4.\u201d This rectangle is followed by an arrow pointing right to a second rectangle. The arrow is labeled, \u201cMolar mass.\u201d The second rectangle is shaded pink and is labeled, \u201cMoles of B a S O subscript 4.\u201d This rectangle is followed by an arrow pointing right to a third rectangle. The arrow is labeled, \u201cStoichiometric factor.\u201d This third rectangle is shaded pink and is labeled, \u201cMoles of M g S O subscript 4.\u201d This rectangle is followed by an arrow labeled, \u201cMolar mass,\u201d which points downward to a fourth rectangle. This fourth rectangle is shaded yellow and is labeled, \u201cMass of M g S O subscript 4.\u201d This rectangle is followed by an arrow labeled, \u201cSample mass,\u201d which points left to a fifth rectangle. This fifth rectangle is shaded lavender and is labeled, \u201cPercent M g S O subscript 4.\" width=\"529\" height=\"250\" class=\"aligncenter\" \/>\r\n<p id=\"fs-idp195163008\">The mass of MgSO<sub>4<\/sub> that would yield the provided precipitate mass is<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idp54876688\">\r\n<p style=\"text-align: center\">$latex 0.6168 \\;\\rule[0.5ex]{3.75em}{0.1ex}\\hspace{-3.75em}\\text{g BaSO}_4 \\times \\frac{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol BaSO}_4}{233.391 \\;\\rule[0.25ex]{2.75em}{0.1ex}\\hspace{-2.75em}\\text{g BaSO}_4} \\times \\frac{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol MgSO}_4}{1\\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol BaSO}_4} \\times \\frac{120.369 \\;\\text{g MgSO}_4}{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol MgSO}_4} = 0.\\underline{3181}08 \\;\\text{g MgSO}_4 \\text{with 4 sig figs}$<\/p>\r\n\r\n<\/div>\r\n<p id=\"fs-idm75196944\">The concentration of MgSO<sub>4<\/sub> in the sample mixture is then calculated to be<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idp13640592\" style=\"text-align: center\">\r\n\r\n$latex \\text{percent MgSO}_4 = \\frac{\\text{mass MgSO}_4}{\\text{mass sample}} \\times 100\\% $\r\n$latex \\frac{\\underline{0.3181}08 \\;\\text{g}}{0.4550 \\;\\text{g}} \\times 100\\% = 69.91\\% $\r\n\r\n<\/div>\r\n&nbsp;\r\n<p id=\"fs-idp29238016\"><em><strong>Test Yourself<\/strong><\/em>\r\nWhat is the percent of chloride ion in a sample if 1.1324 g of the sample produces 1.0881 g of AgCl when treated with excess Ag<sup>+<\/sup>?<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idm30894128\" style=\"text-align: center\">$latex \\text{Ag}^{+}(aq) + \\text{Cl}^{-}(aq) \\longrightarrow \\text{AgCl}(s)$<\/div>\r\n<div><\/div>\r\n<div><em><strong>Answer<\/strong><\/em><\/div>\r\n<div>23.76%<\/div>\r\n<\/div>\r\n<p id=\"fs-idp91356704\">The elemental composition of hydrocarbons and related compounds may be determined via a gravimetric method known as <strong>combustion analysis<\/strong>. In a combustion analysis, a weighed sample of the compound is heated to a high temperature under a stream of oxygen gas, resulting in its complete combustion to yield gaseous products of known identities. The complete combustion of hydrocarbons, for example, will yield carbon dioxide and water as the only products. The gaseous combustion products are swept through separate, preweighed collection devices containing compounds that selectively absorb each product (<a href=\"#CNX_Chem_04_05_combustion\" class=\"autogenerated-content\">Figure 3<\/a>). The mass increase of each device corresponds to the mass of the absorbed product and may be used in an appropriate stoichiometric calculation to derive the mass of the relevant element.<\/p>\r\n\r\n<figure id=\"CNX_Chem_04_05_combustion\"><figcaption>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1300\"]<a href=\"https:\/\/opentextbc.ca\/chemistry\/wp-content\/uploads\/sites\/150\/2016\/05\/CNX_Chem_04_05_combustion.jpg\"><img src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_combustion-2.jpg\" alt=\"This diagram shows an arrow pointing from O subscript 2 into a tube that leads into a vessel containing a red material, labeled \u201cSample.\u201d This vessel is inside a blue container with a red inner lining which is labeled \u201cFurnace.\u201d An arrow points from the tube to the right into the vessel above the red sample material. An arrow leads out of this vessel through a tube into a second vessel outside the furnace. An line points from this tube to a label above the diagram that reads \u201cC O subscript 2, H subscript 2 O, O subscript 2, and other gases.\u201d Many small green spheres are visible in the second vessel which is labeled below, \u201cH subscript 2 O absorber such as M g ( C l O subscript 4 ) subscript 2.\u201d An arrow points to the right through the vessel, and another arrow points right heading out of the vessel through a tube into a third vessel. The third vessel contains many small blue spheres. It is labeled \u201cC O subscript 2 absorber such as N a O H.\u201d An arrow points right through this vessel, and a final arrow points out of a tube at the right end of the vessel. Outside the end of this tube at the end of the arrow is the label, \u201cO subscript 2 and other gases.\u201d\" width=\"1300\" height=\"321\" \/><\/a> <strong>Figure 3.<\/strong> This schematic diagram illustrates the basic components of a combustion analysis device for determining the carbon and hydrogen content of a sample.[\/caption]\r\n\r\n<\/figcaption><\/figure>\r\n<div class=\"textbox shaded\" id=\"fs-idp72915680\">\r\n<h3>Example 3<\/h3>\r\n<p id=\"fs-idp125853872\">Polyethylene is a hydrocarbon polymer used to produce food-storage bags and many other flexible plastic items. A combustion analysis of a 0.00126-g sample of polyethylene yields 0.00394 g of CO<sub>2<\/sub> and 0.00161 g of H<sub>2<\/sub>O. What is the empirical formula of polyethylene?<\/p>\r\n&nbsp;\r\n<p id=\"fs-idp59256480\"><strong>Solution<\/strong>\r\nThe primary assumption in this exercise is that all the carbon in the sample combusted is converted to carbon dioxide, and all the hydrogen in the sample is converted to water:<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idp26802128\" style=\"text-align: center\">$latex \\text{C}_\\text{x} \\text{H}_\\text{y}(s) + \\text{excess O}_2(g) \\longrightarrow x\\text{CO}_2(g) + \\frac{y}{2}\\text{H}_2\\text{O}(g)$<\/div>\r\n<p id=\"fs-idp83118528\">Note that a balanced equation is not necessary for the task at hand. To derive the empirical formula of the compound, only the subscripts <em>x<\/em> and <em>y<\/em> are needed.<\/p>\r\n<p id=\"fs-idm26289056\">First, calculate the molar amounts of carbon and hydrogen in the sample, using the provided masses of the carbon dioxide and water, respectively. With these molar amounts, the empirical formula for the compound may be written as described in the previous chapter of this text. An outline of this approach is given in the following flow chart:<\/p>\r\n<img src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_combmap_img-2.jpg\" alt=\"This figure shows two flowcharts. The first row is a single flow chart. In this row, a rectangle at the left is shaded yellow and is labeled, \u201cMass of C O subscript 2.\u201d This rectangle is followed by an arrow pointing right to a second rectangle. The arrow is labeled, \u201cMolar mass.\u201d The second rectangle is shaded pink and is labeled, \u201cMoles of C O subscript 2.\u201d This rectangle is followed by an arrow pointing right to a third rectangle. The arrow is labeled, \u201cStoichiometric factor.\u201d The third rectangle is shaded pink and is labeled, \u201cMoles of C.\u201d This rectangle is followed by an arrow labeled \u201cMolar mass\u201d which points right to a fourth rectangle. The fourth rectangle is shaded yellow and is labeled \u201cMass of C.\u201d Below, is a second flowchart. It begins with a yellow shaded rectangle on the left which is labeled, \u201cMass of H subscript 2 O.\u201d This rectangle is followed by an arrow labeled, \u201cMolar mass,\u201d which points right to a second rectangle. The second rectangle is shaded pink and is labeled, \u201cMoles of H subscript 2 O.\u201d This rectangle is followed by an arrow pointing right to a third rectangle. The arrow is labeled, \u201cStoichiometric factor.\u201d The third rectangle is shaded pink and is labeled \u201cMoles of H.\u201d This rectangle is followed to the right by an arrow labeled, \u201cMolar mass,\u201d which points to a fourth rectangle. The fourth rectangle is shaded yellow and is labeled \u201cMass of H.\u201d An arrow labeled, \u201cSample mass\u201d points down beneath this rectangle to a green shaded rectangle. This rectangle is labeled, \u201cPercent composition.\u201d An arrow extends beneath the pink rectangle labeled, \u201cMoles of H,\u201d to a green shaded rectangle labeled, \u201cC to H mole ratio.\u201d Beneath this rectangle, an arrow extends to a second green shaded rectangle which is labeled, \u201cEmpirical formula.\u201d\" width=\"572\" height=\"431\" class=\"aligncenter\" \/>\r\n<div class=\"equation\" id=\"fs-idp216199216\" style=\"text-align: center\">$latex \\begin{array} {r @{{}={}} l} \\text{mol C} &amp; 0.00394 \\;\\text{g CO}_2 \\times \\frac{1 \\;\\text{mol CO}_2}{44.010 \\;\\text{g\/mol}} \\times \\frac{1 \\;\\text{mol C}}{1 \\;\\text{mol CO}_2} = \\underline{8.95}3 \\times 10^{-5} \\;\\text{mol C with 3 sig figs} \\\\[1em] \\text{mol H} &amp; 0.00161 \\;\\text{g H}_2 \\text{O} \\times \\frac{1 \\;\\text{mol H}_2 \\text{O}}{18.0153 \\;\\text{g\/mol}} \\times \\frac{2 \\;\\text{mol H}}{1 \\;\\text{mol H}_2 \\text{O}} = \\underline{1.78}74 \\times 10^{-4} \\;\\text{mol H with 3 sig figs} \\end{array}$<\/div>\r\n<p id=\"fs-idp27785296\">The empirical formula for the compound is then derived by identifying the smallest whole-number multiples for these molar amounts. The H-to-C molar ratio is<\/p>\r\n\r\n<div class=\"equation\" id=\"fs-idm23849536\" style=\"text-align: center\">$latex \\frac{\\text{mol H}}{\\text{mol C}} = \\frac{\\underline{1.78}74 \\times 10^{-4}\\;\\text{mol H}}{\\underline{8.95}3 \\times 10^{-5}\\;\\text{mol C}} = \\frac{2 \\;\\text{mol H}}{1 \\;\\text{mol C}}$<\/div>\r\n<p id=\"fs-idp87456800\">and the empirical formula for polyethylene is CH<sub>2<\/sub>.<\/p>\r\n&nbsp;\r\n<p id=\"fs-idp3642976\"><em><strong>Test Yourself<\/strong><\/em>\r\nA 0.00215-g sample of polystyrene, a polymer composed of carbon and hydrogen, produced 0.00726 g of CO<sub>2<\/sub> and 0.00148 g of H<sub>2<\/sub>O in a combustion analysis. What is the empirical formula for polystyrene?<\/p>\r\n&nbsp;\r\n\r\n<em><strong>Answer<\/strong><\/em>\r\n\r\nCH\r\n\r\n<\/div>\r\n<\/section><section id=\"fs-idp138667680\" class=\"summary\">\r\n<h2>Key Concepts and Summary<\/h2>\r\n<p id=\"fs-idp61279744\">The stoichiometry of chemical reactions may serve as the basis for quantitative chemical analysis methods. Titrations involve measuring the volume of a titrant solution required to completely react with a sample solution. This volume is then used to calculate the concentration of analyte in the sample using the stoichiometry of the titration reaction. Gravimetric analysis involves separating the analyte from the sample by a physical or chemical process, determining its mass, and then calculating its concentration in the sample based on the stoichiometry of the relevant process. Combustion analysis is a gravimetric method used to determine the elemental composition of a compound by collecting and weighing the gaseous products of its combustion.<\/p>\r\n\r\n<\/section><section id=\"fs-idp47287072\" class=\"exercises\">\r\n<div class=\"bcc-box bcc-info\">\r\n<h3>Exercises<\/h3>\r\n1. Titration of a 20.0-mL sample of acid rain required 1.7 mL of 0.0811 <em>M<\/em> NaOH to reach the end point. If we assume that the acidity of the rain is due to the presence of sulfuric acid, what was the concentration of sulfuric acid in this sample of rain?\r\n\r\n2. In a common medical laboratory determination of the concentration of free chloride ion in blood serum, a serum sample is titrated with a Hg(NO<sub>3<\/sub>)<sub>2<\/sub> solution.\r\n$latex 2\\text{Cl}^{-}(aq) + \\text{Hg(NO}_3)_2(aq) \\longrightarrow {2\\text{NO}_3}^{-}(aq) + \\text{HgCl}_2(s)$\r\n<p id=\"fs-idm1068656\">What is the Cl<sup>\u2212<\/sup> concentration in a 0.25-mL sample of normal serum that requires 1.46 mL of 8.25 \u00d7 10<sup>\u22124<\/sup><em>M<\/em> Hg(NO<sub>3<\/sub>)<sub>2<\/sub>(<em>aq<\/em>) to reach the end point?<\/p>\r\n3. A sample of gallium bromide, GaBr<sub>2<\/sub>, weighing 0.165 g was dissolved in water and treated with silver nitrate, AgNO<sub>3<\/sub>, resulting in the precipitation of 0.299 g AgBr. Use these data to compute the %Ga (by mass) GaBr<sub>2<\/sub>.\r\n\r\n4. A 0.025-g sample of a compound composed of boron and hydrogen, with a molecular mass of ~28 amu, burns spontaneously when exposed to air, producing 0.063 g of B<sub>2<\/sub>O<sub>3<\/sub>. What are the empirical and molecular formulas of the compound?\r\n\r\n5. What volume of 0.600 <em>M<\/em> HCl is required to react completely with 2.50 g of sodium hydrogen carbonate?\r\n$latex \\text{NaHCO}_3(aq) + \\text{HCl}(aq) \\longrightarrow \\text{NaCl}(aq) + \\text{CO}_2(g) + \\text{H}_2 \\text{O}(l)$\r\n\r\n6. What volume of a 0.3300-<em>M<\/em> solution of sodium hydroxide would be required to titrate 15.00 mL of 0.1500 <em>M<\/em> oxalic acid?\r\n$latex \\text{C}_2 \\text{O}_4 \\text{H}_2(aq) + 2\\text{NaOH}(aq) \\longrightarrow \\text{Na}_2 \\text{C}_2 \\text{O}_4(aq) + 2\\text{H}_2 \\text{O}(l)$\r\n\r\n7. A sample of solid calcium hydroxide, Ca(OH)<sub>2<\/sub>, is allowed to stand in water until a saturated solution is formed. A titration of 75.00 mL of this solution with 5.00 \u00d7 10<sup>\u22122<\/sup><em>M<\/em> HCl requires 36.6 mL of the acid to reach the end point.\r\n$latex \\text{Ca(OH)}_2(aq) + 2\\text{HCl}(aq) \\longrightarrow \\text{CaCl}_2(aq) + 2\\text{H}_2 \\text{O}(l) $\r\n<p id=\"fs-idm404608\">What is the molarity?<\/p>\r\n8. How many milliliters of a 0.1500-<em>M<\/em> solution of KOH will be required to titrate 40.00 mL of a 0.0656-<em>M<\/em> solution of H<sub>3<\/sub>PO<sub>4<\/sub>?\r\n$latex \\text{H}_3\\text{PO}_4(aq) + 2\\text{KOH}(aq) \\longrightarrow \\text{K}_2 \\text{HPO}_4(aq) + 2\\text{H}_2 \\text{O}(l)$\r\n\r\n9. The reaction of WCl<sub>6<\/sub> with Al at ~400 \u00b0C gives black crystals of a compound containing only tungsten and chlorine. A sample of this compound, when reduced with hydrogen, gives 0.2232 g of tungsten metal and hydrogen chloride, which is absorbed in water. Titration of the hydrochloric acid thus produced requires 46.2 mL of 0.1051 <em>M<\/em> NaOH to reach the end point. What is the empirical formula of the black tungsten chloride?\r\n\r\n&nbsp;\r\n\r\n<strong>Answers<\/strong>\r\n<p id=\"fs-idp29571152\">1. 3.4 \u00d7 10<sup>\u22123<\/sup><em>M<\/em> H<sub>2<\/sub>SO<sub>4<\/sub><\/p>\r\n<p id=\"fs-idm88200368\">2. 9.6 \u00d7 10<sup>\u22123<\/sup><em>M<\/em> Cl<sup>\u2212<\/sup><\/p>\r\n<p id=\"fs-idp61124608\">3. 22.4%<\/p>\r\n<p id=\"fs-idp18571504\">4. The empirical formula is BH<sub>3<\/sub>. The molecular formula is B<sub>2<\/sub>H<sub>6<\/sub>.<\/p>\r\n<p id=\"fs-idp51612096\">5. 49.6 mL<\/p>\r\n<p id=\"fs-idm27864640\">6. 13.64 mL<\/p>\r\n<p id=\"fs-idm9471168\">7. 1.22 <em>M<\/em><\/p>\r\n<p id=\"fs-idp46830048\">8. 34.99 mL KOH<\/p>\r\n<p id=\"fs-idp66345312\">9. The empirical formula is WCl<sub>4<\/sub>.<\/p>\r\n\r\n<\/div>\r\n<\/section>\r\n<div>\r\n<h2>Glossary<\/h2>\r\n<strong>analyze:\u00a0<\/strong>chemical species of interest\r\n\r\n<strong>buret:\u00a0<\/strong>device used for the precise delivery of variable liquid volumes, such as in a titration analysis\r\n\r\n<strong>combustion analysis:\u00a0<\/strong>gravimetric technique used to determine the elemental composition of a compound via the collection and weighing of its gaseous combustion products\r\n\r\n<strong>end point:\u00a0<\/strong>measured volume of titrant solution that yields the change in sample solution appearance or other property expected for stoichiometric equivalence (see <em>equivalence point<\/em>)\r\n\r\n<strong>equivalence point:\u00a0<\/strong>volume of titrant solution required to react completely with the analyte in a titration analysis; provides a stoichiometric amount of titrant for the sample\u2019s analyte according to the titration reaction\r\n\r\n<strong>gravimetric analysis:\u00a0<\/strong>quantitative chemical analysis method involving the separation of an analyte from a sample by a physical or chemical process and subsequent mass measurements of the analyte, reaction product, and\/or sample\r\n\r\n<strong>indicator:\u00a0<\/strong>substance added to the sample in a titration analysis to permit visual detection of the end point\r\n\r\n<strong>quantitative analysis:\u00a0<\/strong>the determination of the amount or concentration of a substance in a sample\r\n\r\n<strong>titrant:\u00a0<\/strong>solution containing a known concentration of substance that will react with the analyte in a titration analysis\r\n\r\n<strong>titration analysis:\u00a0<\/strong>quantitative chemical analysis method that involves measuring the volume of a reactant solution required to completely react with the analyte in a sample\r\n\r\n<\/div>","rendered":"<div class=\"bcc-box bcc-highlight\">\n<h3>Learning Objectives<\/h3>\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Describe the fundamental aspects of titrations and gravimetric analysis.<\/li>\n<li>Perform stoichiometric calculations using typical titration and gravimetric data.<\/li>\n<\/ul>\n<\/div>\n<p id=\"fs-idp138930544\">In the 18th century, the strength (actually the concentration) of vinegar samples was determined by noting the amount of potassium carbonate, K<sub>2<\/sub>CO<sub>3<\/sub>, which had to be added, a little at a time, before bubbling ceased. The greater the weight of potassium carbonate added to reach the point where the bubbling ended, the more concentrated the vinegar.<\/p>\n<p id=\"fs-idm17525264\">We now know that the effervescence that occurred during this process was due to reaction with acetic acid, CH<sub>3<\/sub>CO<sub>2<\/sub>H, the compound primarily responsible for the odor and taste of vinegar. Acetic acid reacts with potassium carbonate according to the following equation:<\/p>\n<div class=\"equation\" id=\"fs-idm1518128\" style=\"text-align: center\">[latex]2\\text{CH}_3 \\text{CO}_2 \\text{H}(aq) + \\text{K}_2\\text{CO}_3(s) \\longrightarrow \\text{KCH}_3 \\text{CO}_3(aq) + \\text{CO}_2(g) + \\text{H}_2 \\text{O}(l)[\/latex]<\/div>\n<p id=\"fs-idp89786672\">The bubbling was due to the production of CO<sub>2<\/sub>.<\/p>\n<p id=\"fs-idp55621088\">The test of vinegar with potassium carbonate is one type of <strong>quantitative analysis<\/strong>\u2014the determination of the amount or concentration of a substance in a sample. In the analysis of vinegar, the concentration of the solute (acetic acid) was determined from the amount of reactant that combined with the solute present in a known volume of the solution. In other types of chemical analyses, the amount of a substance present in a sample is determined by measuring the amount of product that results.<\/p>\n<section id=\"fs-idp85215712\">\n<h2>Titration<\/h2>\n<p id=\"fs-idp43277952\">The described approach to measuring vinegar strength was an early version of the analytical technique known as <strong>titration analysis<\/strong>. A typical titration analysis involves the use of a <strong>buret<\/strong> (<a href=\"#CNX_Chem_04_05_titration\" class=\"autogenerated-content\">Figure 1<\/a>) to make incremental additions of a solution containing a known concentration of some substance (the <strong>titrant<\/strong>) to a sample solution containing the substance whose concentration is to be measured (the <strong>analyte<\/strong>). The titrant and analyte undergo a chemical reaction of known stoichiometry, and so measuring the volume of titrant solution required for complete reaction with the analyte (the <strong>equivalence point<\/strong> of the titration) allows calculation of the analyte concentration. The equivalence point of a titration may be detected visually if a distinct change in the appearance of the sample solution accompanies the completion of the reaction. The halt of bubble formation in the classic vinegar analysis is one such example, though, more commonly, special dyes called <strong>indicators<\/strong> are added to the sample solutions to impart a change in color at or very near the equivalence point of the titration. Equivalence points may also be detected by measuring some solution property that changes in a predictable way during the course of the titration. Regardless of the approach taken to detect a titration\u2019s equivalence point, the volume of titrant actually measured is called the <strong>end point<\/strong>. Properly designed titration methods typically ensure that the difference between the equivalence and end points is negligible. Though any type of chemical reaction may serve as the basis for a titration analysis, the three described in this chapter (precipitation, acid-base, and redox) are most common. Additional details regarding titration analysis are provided in the chapter on acid-base equilibria.<\/p>\n<figure id=\"CNX_Chem_04_05_titration\"><figcaption>\n<figure style=\"width: 527px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/opentextbc.ca\/chemistry\/wp-content\/uploads\/sites\/150\/2016\/05\/CNX_Chem_04_05_titration.jpg\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_titration-2.jpg\" alt=\"Two pictures are shown. In a, a person is shown pouring a liquid from a small beaker into a buret. The person is wearing goggles and gloves as she transfers the solution into the buret. In b, a close up view of the markings on the side of the buret is shown. The markings for 10, 15, and 20 are clearly shown with horizontal rings printed on the buret. Between each of these whole number markings, half markings are also clearly shown with horizontal line segment markings.\" width=\"527\" height=\"405\" class=\"\" \/><\/a><figcaption class=\"wp-caption-text\"><strong>Figure 1.<\/strong> (a) A student fills a buret in preparation for a titration analysis. (b) A typical buret permits volume measurements to the nearest 0.1 mL. (credit a: modification of work by Mark Blaser and Matt Evans; credit b: modification of work by Mark Blaser and Matt Evans)<\/figcaption><\/figure>\n<\/figcaption><\/figure>\n<div class=\"textbox shaded\" id=\"fs-idp80717680\">\n<h3>Example 1<\/h3>\n<p id=\"fs-idp32280496\">The end point in a titration of a 50.00-mL sample of aqueous HCl was reached by addition of 35.23 mL of 0.250 M NaOH titrant. The titration reaction is:<\/p>\n<div class=\"equation\" id=\"fs-idp79702544\">\n<p style=\"text-align: center\">[latex]\\text{HCl}(aq) + \\text{NaOH}(aq) \\longrightarrow \\text{NaCl}(aq) + \\text{H}_2\\text{O}(l)[\/latex]<\/p>\n<\/div>\n<p id=\"fs-idp86323376\">What is the molarity of the HCl?<\/p>\n<p>&nbsp;<\/p>\n<p id=\"fs-idm12137328\"><strong>Solution<\/strong><\/p>\n<p>As for all reaction stoichiometry calculations, the key issue is the relation between the molar amounts of the chemical species of interest as depicted in the balanced chemical equation. The approach outlined in previous modules of this chapter is followed, with additional considerations required, since the amounts of reactants provided and requested are expressed as solution concentrations.<\/p>\n<p id=\"fs-idp64054640\">For this exercise, the calculation will follow the following outlined steps:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_map7_img-2.jpg\" alt=\"This figure shows four rectangles. The first is shaded lavender and is labeled, \u201cVolume of N a O H.\u201d This rectangle is followed by an arrow pointing right which is labeled, \u201cMolar concentration,\u201d to a second rectangle. This second rectangle is shaded pink and is labeled, \u201cMoles of N a O H.\u201d This rectangle is followed by an arrow pointing right which is labeled, \u201cStoichiometric factor,\u201d to a third rectangle which is shaded pink and is labeled, \u201cMoles of H C l.\u201d This rectangle is followed by an arrow labeled, \u201cSolution volume,\u201d which points right to a fourth rectangle. This fourth rectangle is shaded lavender and is labeled, \u201cConcentration of H C l.\u201d\" width=\"533\" height=\"237\" class=\"aligncenter\" \/><\/p>\n<p id=\"fs-idp137498176\">The molar amount of HCl is calculated to be:<\/p>\n<div class=\"equation\" id=\"fs-idp60191360\" style=\"text-align: center\">[latex]35.23 \\;\\rule[0.5ex]{4.5em}{0.1ex}\\hspace{-4.5em}\\text{mL NaOH} \\times \\frac{1 \\;\\rule[0.25ex]{0.5em}{0.1ex}\\hspace{-0.5em}\\text{L}}{1000 \\rule[0.25ex]{1.25em}{0.1ex}\\hspace{-1.25em}\\;\\text{mL}} \\times \\frac{0.250 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol NaOH}}{1 \\;\\rule[0.25ex]{0.5em}{0.1ex}\\hspace{-0.5em}\\text{L}} \\times \\frac{1 \\;\\text{mol HCl}}{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol NaOH}} = \\underline{8.80}75 \\times 10^{-3} \\;\\text{mol HCl with 3 sig figs}[\/latex]<\/div>\n<p id=\"fs-idp18819536\">Using the provided volume of HCl solution and the definition of molarity, the HCl concentration is:<\/p>\n<div class=\"equation\" id=\"fs-idp180416144\" style=\"text-align: center\">[latex]\\begin{array}{r @{{}={}} l} M & \\frac{\\text{mol HCl}}{\\text{L solution}} \\\\[1em] M & \\frac{\\underline{8.80}75 \\times 10^{-3} \\;\\text{mol HCl}}{50.00 \\;\\text{mL} \\times \\frac{1 \\;\\text{L}}{1000 \\;\\text{mL}}} \\\\[1em] M & 0.176 \\;M \\end{array}[\/latex]<\/div>\n<p id=\"fs-idp24080800\">Note: For these types of titration calculations, it is convenient to recognize that solution molarity is also equal to the number of <em>milli<\/em>moles of solute per <em>milli<\/em>liter of solution:<\/p>\n<div class=\"equation\" id=\"fs-idm39309120\" style=\"text-align: center\">[latex]M = \\frac{\\text{mol solute}}{\\text{L solution}} \\times \\frac{\\frac{10^3 \\;\\text{mmol}}{\\text{mol}}}{\\frac{10^3 \\;\\text{mL}}{\\text{L}}} = \\frac{\\text{mmol solute}}{\\text{mL solution}}[\/latex]<\/div>\n<p id=\"fs-idm35999792\">Using this version of the molarity unit will shorten the calculation by eliminating two conversion factors:<\/p>\n<div class=\"equation\" id=\"fs-idm27436528\">\n<p style=\"text-align: center\">[latex]\\frac{35.23 \\;\\text{mL NaOH} \\times \\;\\frac{0.250 \\;\\text{mmol NaOH}}{\\text{mL NaOH}} \\times \\frac{1 \\;\\text{mmol HCl}}{1 \\;\\text{mmol NaOH}}}{50.00 \\;\\text{mL solution}} = 0.176 \\;M \\;\\text{HCl}[\/latex]<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p id=\"fs-idm12966032\"><em><strong>Test Yourself<\/strong><\/em><br \/>\nA 20.00-mL sample of aqueous oxalic acid, H<sub>2<\/sub>C<sub>2<\/sub>O<sub>4<\/sub>, was titrated with a 0.09113-<em>M<\/em> solution of potassium permanganate.<\/p>\n<div class=\"equation\" id=\"fs-idm30080224\" style=\"text-align: center\">[latex]{2\\text{MnO}_4}^{-}(aq) + 5\\text{H}_2 \\text{C}_2 \\text{O}_4(aq) + 6\\text{H}^{+}(aq) \\longrightarrow 10\\text{CO}_2(g) + 2\\text{Mn}^{2+}(aq) + 8\\text{H}_2 \\text{O}(l)[\/latex]<\/div>\n<p id=\"fs-idm46826912\">A volume of 23.24 mL was required to reach the end point. What is the oxalic acid molarity?<\/p>\n<p>&nbsp;<\/p>\n<p><em><strong>Answer<\/strong><\/em><\/p>\n<p>0.2648 M<\/p>\n<\/div>\n<\/section>\n<section id=\"fs-idp68434144\">\n<h2>Gravimetric Analysis<\/h2>\n<p id=\"fs-idp27521328\">A <strong>gravimetric analysis<\/strong> is one in which a sample is subjected to some treatment that causes a change in the physical state of the analyte that permits its separation from the other components of the sample. Mass measurements of the sample, the isolated analyte, or some other component of the analysis system, used along with the known stoichiometry of the compounds involved, permit calculation of the analyte concentration. Gravimetric methods were the first techniques used for quantitative chemical analysis, and they remain important tools in the modern chemistry laboratory.<\/p>\n<p>The required change of state in a gravimetric analysis may be achieved by various physical and chemical processes. For example, the moisture (water) content of a sample is routinely determined by measuring the mass of a sample before and after it is subjected to a controlled heating process that evaporates the water. Also common are gravimetric techniques in which the analyte is subjected to a precipitation reaction of the sort described earlier in this chapter. The precipitate is typically isolated from the reaction mixture by filtration, carefully dried, and then weighed (<a href=\"#CNX_Chem_04_05_Filter\" class=\"autogenerated-content\">Figure 2<\/a>). The mass of the precipitate may then be used, along with relevant stoichiometric relationships, to calculate analyte concentration.<\/p>\n<\/section>\n<section id=\"fs-idp68434144\">\n<figure id=\"CNX_Chem_04_05_Filter\">\n<figure style=\"width: 217px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/opentextbc.ca\/chemistry\/wp-content\/uploads\/sites\/150\/2016\/05\/CNX_Chem_04_05_filter.jpg\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_filter-2.jpg\" alt=\"A photo is shown of a flask and funnel used for filtration. The flask contains a slightly opaque liquid filtrate with a slight yellow tint. A funnel, which contains a bright yellow and orange material, sits atop the flask. The flask is held in place by a clamp and is connected to a vacuum line. The connection between the funnel and flask is sealed with a rubber bung or gasket.\" width=\"217\" height=\"351\" class=\"\" \/><\/a><figcaption class=\"wp-caption-text\"><strong>Figure 2.<\/strong> Precipitate may be removed from a reaction mixture by filtration.<\/figcaption><\/figure>\n<\/figure>\n<\/section>\n<section id=\"fs-idp68434144\">\n<div class=\"textbox shaded\" id=\"fs-idp69077568\">\n<h3>Example 2<\/h3>\n<p>A 0.4550-g solid mixture containing MgSO<sub>4<\/sub> is dissolved in water and treated with an excess of Ba(NO<sub>3<\/sub>)<sub>2<\/sub>, resulting in the precipitation of 0.6168 g of BaSO<sub>4<\/sub>.<\/p>\n<div class=\"equation\" id=\"fs-idm25559056\" style=\"text-align: center\">[latex]\\text{MgSO}_4(aq) + \\text{Ba(NO}_3)_2(aq) \\longrightarrow \\text{BaSO}_4(s) + \\text{Mg(NO}_3)_2(aq)[\/latex]<\/div>\n<p id=\"fs-idp114808768\">What is the concentration (percent) of MgSO<sub>4<\/sub> in the mixture?<\/p>\n<p>&nbsp;<\/p>\n<p id=\"fs-idp87548576\"><strong>Solution<\/strong><\/p>\n<p>The plan for this calculation is similar to others used in stoichiometric calculations, the central step being the connection between the moles of BaSO<sub>4<\/sub> and MgSO<sub>4<\/sub> through their stoichiometric factor. Once the mass of MgSO<sub>4<\/sub> is computed, it may be used along with the mass of the sample mixture to calculate the requested percentage concentration.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_map8_img-2.jpg\" alt=\"This figure shows five rectangles. The first is shaded yellow and is labeled \u201cMass of B a S O subscript 4.\u201d This rectangle is followed by an arrow pointing right to a second rectangle. The arrow is labeled, \u201cMolar mass.\u201d The second rectangle is shaded pink and is labeled, \u201cMoles of B a S O subscript 4.\u201d This rectangle is followed by an arrow pointing right to a third rectangle. The arrow is labeled, \u201cStoichiometric factor.\u201d This third rectangle is shaded pink and is labeled, \u201cMoles of M g S O subscript 4.\u201d This rectangle is followed by an arrow labeled, \u201cMolar mass,\u201d which points downward to a fourth rectangle. This fourth rectangle is shaded yellow and is labeled, \u201cMass of M g S O subscript 4.\u201d This rectangle is followed by an arrow labeled, \u201cSample mass,\u201d which points left to a fifth rectangle. This fifth rectangle is shaded lavender and is labeled, \u201cPercent M g S O subscript 4.\" width=\"529\" height=\"250\" class=\"aligncenter\" \/><\/p>\n<p id=\"fs-idp195163008\">The mass of MgSO<sub>4<\/sub> that would yield the provided precipitate mass is<\/p>\n<div class=\"equation\" id=\"fs-idp54876688\">\n<p style=\"text-align: center\">[latex]0.6168 \\;\\rule[0.5ex]{3.75em}{0.1ex}\\hspace{-3.75em}\\text{g BaSO}_4 \\times \\frac{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol BaSO}_4}{233.391 \\;\\rule[0.25ex]{2.75em}{0.1ex}\\hspace{-2.75em}\\text{g BaSO}_4} \\times \\frac{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol MgSO}_4}{1\\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol BaSO}_4} \\times \\frac{120.369 \\;\\text{g MgSO}_4}{1 \\;\\rule[0.25ex]{3.5em}{0.1ex}\\hspace{-3.5em}\\text{mol MgSO}_4} = 0.\\underline{3181}08 \\;\\text{g MgSO}_4 \\text{with 4 sig figs}[\/latex]<\/p>\n<\/div>\n<p id=\"fs-idm75196944\">The concentration of MgSO<sub>4<\/sub> in the sample mixture is then calculated to be<\/p>\n<div class=\"equation\" id=\"fs-idp13640592\" style=\"text-align: center\">\n<p>[latex]\\text{percent MgSO}_4 = \\frac{\\text{mass MgSO}_4}{\\text{mass sample}} \\times 100\\%[\/latex]<br \/>\n[latex]\\frac{\\underline{0.3181}08 \\;\\text{g}}{0.4550 \\;\\text{g}} \\times 100\\% = 69.91\\%[\/latex]<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p id=\"fs-idp29238016\"><em><strong>Test Yourself<\/strong><\/em><br \/>\nWhat is the percent of chloride ion in a sample if 1.1324 g of the sample produces 1.0881 g of AgCl when treated with excess Ag<sup>+<\/sup>?<\/p>\n<div class=\"equation\" id=\"fs-idm30894128\" style=\"text-align: center\">[latex]\\text{Ag}^{+}(aq) + \\text{Cl}^{-}(aq) \\longrightarrow \\text{AgCl}(s)[\/latex]<\/div>\n<div><\/div>\n<div><em><strong>Answer<\/strong><\/em><\/div>\n<div>23.76%<\/div>\n<\/div>\n<p id=\"fs-idp91356704\">The elemental composition of hydrocarbons and related compounds may be determined via a gravimetric method known as <strong>combustion analysis<\/strong>. In a combustion analysis, a weighed sample of the compound is heated to a high temperature under a stream of oxygen gas, resulting in its complete combustion to yield gaseous products of known identities. The complete combustion of hydrocarbons, for example, will yield carbon dioxide and water as the only products. The gaseous combustion products are swept through separate, preweighed collection devices containing compounds that selectively absorb each product (<a href=\"#CNX_Chem_04_05_combustion\" class=\"autogenerated-content\">Figure 3<\/a>). The mass increase of each device corresponds to the mass of the absorbed product and may be used in an appropriate stoichiometric calculation to derive the mass of the relevant element.<\/p>\n<figure id=\"CNX_Chem_04_05_combustion\"><figcaption>\n<figure style=\"width: 1300px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/opentextbc.ca\/chemistry\/wp-content\/uploads\/sites\/150\/2016\/05\/CNX_Chem_04_05_combustion.jpg\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_combustion-2.jpg\" alt=\"This diagram shows an arrow pointing from O subscript 2 into a tube that leads into a vessel containing a red material, labeled \u201cSample.\u201d This vessel is inside a blue container with a red inner lining which is labeled \u201cFurnace.\u201d An arrow points from the tube to the right into the vessel above the red sample material. An arrow leads out of this vessel through a tube into a second vessel outside the furnace. An line points from this tube to a label above the diagram that reads \u201cC O subscript 2, H subscript 2 O, O subscript 2, and other gases.\u201d Many small green spheres are visible in the second vessel which is labeled below, \u201cH subscript 2 O absorber such as M g ( C l O subscript 4 ) subscript 2.\u201d An arrow points to the right through the vessel, and another arrow points right heading out of the vessel through a tube into a third vessel. The third vessel contains many small blue spheres. It is labeled \u201cC O subscript 2 absorber such as N a O H.\u201d An arrow points right through this vessel, and a final arrow points out of a tube at the right end of the vessel. Outside the end of this tube at the end of the arrow is the label, \u201cO subscript 2 and other gases.\u201d\" width=\"1300\" height=\"321\" \/><\/a><figcaption class=\"wp-caption-text\"><strong>Figure 3.<\/strong> This schematic diagram illustrates the basic components of a combustion analysis device for determining the carbon and hydrogen content of a sample.<\/figcaption><\/figure>\n<\/figcaption><\/figure>\n<div class=\"textbox shaded\" id=\"fs-idp72915680\">\n<h3>Example 3<\/h3>\n<p id=\"fs-idp125853872\">Polyethylene is a hydrocarbon polymer used to produce food-storage bags and many other flexible plastic items. A combustion analysis of a 0.00126-g sample of polyethylene yields 0.00394 g of CO<sub>2<\/sub> and 0.00161 g of H<sub>2<\/sub>O. What is the empirical formula of polyethylene?<\/p>\n<p>&nbsp;<\/p>\n<p id=\"fs-idp59256480\"><strong>Solution<\/strong><br \/>\nThe primary assumption in this exercise is that all the carbon in the sample combusted is converted to carbon dioxide, and all the hydrogen in the sample is converted to water:<\/p>\n<div class=\"equation\" id=\"fs-idp26802128\" style=\"text-align: center\">[latex]\\text{C}_\\text{x} \\text{H}_\\text{y}(s) + \\text{excess O}_2(g) \\longrightarrow x\\text{CO}_2(g) + \\frac{y}{2}\\text{H}_2\\text{O}(g)[\/latex]<\/div>\n<p id=\"fs-idp83118528\">Note that a balanced equation is not necessary for the task at hand. To derive the empirical formula of the compound, only the subscripts <em>x<\/em> and <em>y<\/em> are needed.<\/p>\n<p id=\"fs-idm26289056\">First, calculate the molar amounts of carbon and hydrogen in the sample, using the provided masses of the carbon dioxide and water, respectively. With these molar amounts, the empirical formula for the compound may be written as described in the previous chapter of this text. An outline of this approach is given in the following flow chart:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-content\/uploads\/sites\/387\/2018\/04\/CNX_Chem_04_05_combmap_img-2.jpg\" alt=\"This figure shows two flowcharts. The first row is a single flow chart. In this row, a rectangle at the left is shaded yellow and is labeled, \u201cMass of C O subscript 2.\u201d This rectangle is followed by an arrow pointing right to a second rectangle. The arrow is labeled, \u201cMolar mass.\u201d The second rectangle is shaded pink and is labeled, \u201cMoles of C O subscript 2.\u201d This rectangle is followed by an arrow pointing right to a third rectangle. The arrow is labeled, \u201cStoichiometric factor.\u201d The third rectangle is shaded pink and is labeled, \u201cMoles of C.\u201d This rectangle is followed by an arrow labeled \u201cMolar mass\u201d which points right to a fourth rectangle. The fourth rectangle is shaded yellow and is labeled \u201cMass of C.\u201d Below, is a second flowchart. It begins with a yellow shaded rectangle on the left which is labeled, \u201cMass of H subscript 2 O.\u201d This rectangle is followed by an arrow labeled, \u201cMolar mass,\u201d which points right to a second rectangle. The second rectangle is shaded pink and is labeled, \u201cMoles of H subscript 2 O.\u201d This rectangle is followed by an arrow pointing right to a third rectangle. The arrow is labeled, \u201cStoichiometric factor.\u201d The third rectangle is shaded pink and is labeled \u201cMoles of H.\u201d This rectangle is followed to the right by an arrow labeled, \u201cMolar mass,\u201d which points to a fourth rectangle. The fourth rectangle is shaded yellow and is labeled \u201cMass of H.\u201d An arrow labeled, \u201cSample mass\u201d points down beneath this rectangle to a green shaded rectangle. This rectangle is labeled, \u201cPercent composition.\u201d An arrow extends beneath the pink rectangle labeled, \u201cMoles of H,\u201d to a green shaded rectangle labeled, \u201cC to H mole ratio.\u201d Beneath this rectangle, an arrow extends to a second green shaded rectangle which is labeled, \u201cEmpirical formula.\u201d\" width=\"572\" height=\"431\" class=\"aligncenter\" \/><\/p>\n<div class=\"equation\" id=\"fs-idp216199216\" style=\"text-align: center\">[latex]\\begin{array} {r @{{}={}} l} \\text{mol C} & 0.00394 \\;\\text{g CO}_2 \\times \\frac{1 \\;\\text{mol CO}_2}{44.010 \\;\\text{g\/mol}} \\times \\frac{1 \\;\\text{mol C}}{1 \\;\\text{mol CO}_2} = \\underline{8.95}3 \\times 10^{-5} \\;\\text{mol C with 3 sig figs} \\\\[1em] \\text{mol H} & 0.00161 \\;\\text{g H}_2 \\text{O} \\times \\frac{1 \\;\\text{mol H}_2 \\text{O}}{18.0153 \\;\\text{g\/mol}} \\times \\frac{2 \\;\\text{mol H}}{1 \\;\\text{mol H}_2 \\text{O}} = \\underline{1.78}74 \\times 10^{-4} \\;\\text{mol H with 3 sig figs} \\end{array}[\/latex]<\/div>\n<p id=\"fs-idp27785296\">The empirical formula for the compound is then derived by identifying the smallest whole-number multiples for these molar amounts. The H-to-C molar ratio is<\/p>\n<div class=\"equation\" id=\"fs-idm23849536\" style=\"text-align: center\">[latex]\\frac{\\text{mol H}}{\\text{mol C}} = \\frac{\\underline{1.78}74 \\times 10^{-4}\\;\\text{mol H}}{\\underline{8.95}3 \\times 10^{-5}\\;\\text{mol C}} = \\frac{2 \\;\\text{mol H}}{1 \\;\\text{mol C}}[\/latex]<\/div>\n<p id=\"fs-idp87456800\">and the empirical formula for polyethylene is CH<sub>2<\/sub>.<\/p>\n<p>&nbsp;<\/p>\n<p id=\"fs-idp3642976\"><em><strong>Test Yourself<\/strong><\/em><br \/>\nA 0.00215-g sample of polystyrene, a polymer composed of carbon and hydrogen, produced 0.00726 g of CO<sub>2<\/sub> and 0.00148 g of H<sub>2<\/sub>O in a combustion analysis. What is the empirical formula for polystyrene?<\/p>\n<p>&nbsp;<\/p>\n<p><em><strong>Answer<\/strong><\/em><\/p>\n<p>CH<\/p>\n<\/div>\n<\/section>\n<section id=\"fs-idp138667680\" class=\"summary\">\n<h2>Key Concepts and Summary<\/h2>\n<p id=\"fs-idp61279744\">The stoichiometry of chemical reactions may serve as the basis for quantitative chemical analysis methods. Titrations involve measuring the volume of a titrant solution required to completely react with a sample solution. This volume is then used to calculate the concentration of analyte in the sample using the stoichiometry of the titration reaction. Gravimetric analysis involves separating the analyte from the sample by a physical or chemical process, determining its mass, and then calculating its concentration in the sample based on the stoichiometry of the relevant process. Combustion analysis is a gravimetric method used to determine the elemental composition of a compound by collecting and weighing the gaseous products of its combustion.<\/p>\n<\/section>\n<section id=\"fs-idp47287072\" class=\"exercises\">\n<div class=\"bcc-box bcc-info\">\n<h3>Exercises<\/h3>\n<p>1. Titration of a 20.0-mL sample of acid rain required 1.7 mL of 0.0811 <em>M<\/em> NaOH to reach the end point. If we assume that the acidity of the rain is due to the presence of sulfuric acid, what was the concentration of sulfuric acid in this sample of rain?<\/p>\n<p>2. In a common medical laboratory determination of the concentration of free chloride ion in blood serum, a serum sample is titrated with a Hg(NO<sub>3<\/sub>)<sub>2<\/sub> solution.<br \/>\n[latex]2\\text{Cl}^{-}(aq) + \\text{Hg(NO}_3)_2(aq) \\longrightarrow {2\\text{NO}_3}^{-}(aq) + \\text{HgCl}_2(s)[\/latex]<\/p>\n<p id=\"fs-idm1068656\">What is the Cl<sup>\u2212<\/sup> concentration in a 0.25-mL sample of normal serum that requires 1.46 mL of 8.25 \u00d7 10<sup>\u22124<\/sup><em>M<\/em> Hg(NO<sub>3<\/sub>)<sub>2<\/sub>(<em>aq<\/em>) to reach the end point?<\/p>\n<p>3. A sample of gallium bromide, GaBr<sub>2<\/sub>, weighing 0.165 g was dissolved in water and treated with silver nitrate, AgNO<sub>3<\/sub>, resulting in the precipitation of 0.299 g AgBr. Use these data to compute the %Ga (by mass) GaBr<sub>2<\/sub>.<\/p>\n<p>4. A 0.025-g sample of a compound composed of boron and hydrogen, with a molecular mass of ~28 amu, burns spontaneously when exposed to air, producing 0.063 g of B<sub>2<\/sub>O<sub>3<\/sub>. What are the empirical and molecular formulas of the compound?<\/p>\n<p>5. What volume of 0.600 <em>M<\/em> HCl is required to react completely with 2.50 g of sodium hydrogen carbonate?<br \/>\n[latex]\\text{NaHCO}_3(aq) + \\text{HCl}(aq) \\longrightarrow \\text{NaCl}(aq) + \\text{CO}_2(g) + \\text{H}_2 \\text{O}(l)[\/latex]<\/p>\n<p>6. What volume of a 0.3300-<em>M<\/em> solution of sodium hydroxide would be required to titrate 15.00 mL of 0.1500 <em>M<\/em> oxalic acid?<br \/>\n[latex]\\text{C}_2 \\text{O}_4 \\text{H}_2(aq) + 2\\text{NaOH}(aq) \\longrightarrow \\text{Na}_2 \\text{C}_2 \\text{O}_4(aq) + 2\\text{H}_2 \\text{O}(l)[\/latex]<\/p>\n<p>7. A sample of solid calcium hydroxide, Ca(OH)<sub>2<\/sub>, is allowed to stand in water until a saturated solution is formed. A titration of 75.00 mL of this solution with 5.00 \u00d7 10<sup>\u22122<\/sup><em>M<\/em> HCl requires 36.6 mL of the acid to reach the end point.<br \/>\n[latex]\\text{Ca(OH)}_2(aq) + 2\\text{HCl}(aq) \\longrightarrow \\text{CaCl}_2(aq) + 2\\text{H}_2 \\text{O}(l)[\/latex]<\/p>\n<p id=\"fs-idm404608\">What is the molarity?<\/p>\n<p>8. How many milliliters of a 0.1500-<em>M<\/em> solution of KOH will be required to titrate 40.00 mL of a 0.0656-<em>M<\/em> solution of H<sub>3<\/sub>PO<sub>4<\/sub>?<br \/>\n[latex]\\text{H}_3\\text{PO}_4(aq) + 2\\text{KOH}(aq) \\longrightarrow \\text{K}_2 \\text{HPO}_4(aq) + 2\\text{H}_2 \\text{O}(l)[\/latex]<\/p>\n<p>9. The reaction of WCl<sub>6<\/sub> with Al at ~400 \u00b0C gives black crystals of a compound containing only tungsten and chlorine. A sample of this compound, when reduced with hydrogen, gives 0.2232 g of tungsten metal and hydrogen chloride, which is absorbed in water. Titration of the hydrochloric acid thus produced requires 46.2 mL of 0.1051 <em>M<\/em> NaOH to reach the end point. What is the empirical formula of the black tungsten chloride?<\/p>\n<p>&nbsp;<\/p>\n<p><strong>Answers<\/strong><\/p>\n<p id=\"fs-idp29571152\">1. 3.4 \u00d7 10<sup>\u22123<\/sup><em>M<\/em> H<sub>2<\/sub>SO<sub>4<\/sub><\/p>\n<p id=\"fs-idm88200368\">2. 9.6 \u00d7 10<sup>\u22123<\/sup><em>M<\/em> Cl<sup>\u2212<\/sup><\/p>\n<p id=\"fs-idp61124608\">3. 22.4%<\/p>\n<p id=\"fs-idp18571504\">4. The empirical formula is BH<sub>3<\/sub>. The molecular formula is B<sub>2<\/sub>H<sub>6<\/sub>.<\/p>\n<p id=\"fs-idp51612096\">5. 49.6 mL<\/p>\n<p id=\"fs-idm27864640\">6. 13.64 mL<\/p>\n<p id=\"fs-idm9471168\">7. 1.22 <em>M<\/em><\/p>\n<p id=\"fs-idp46830048\">8. 34.99 mL KOH<\/p>\n<p id=\"fs-idp66345312\">9. The empirical formula is WCl<sub>4<\/sub>.<\/p>\n<\/div>\n<\/section>\n<div>\n<h2>Glossary<\/h2>\n<p><strong>analyze:\u00a0<\/strong>chemical species of interest<\/p>\n<p><strong>buret:\u00a0<\/strong>device used for the precise delivery of variable liquid volumes, such as in a titration analysis<\/p>\n<p><strong>combustion analysis:\u00a0<\/strong>gravimetric technique used to determine the elemental composition of a compound via the collection and weighing of its gaseous combustion products<\/p>\n<p><strong>end point:\u00a0<\/strong>measured volume of titrant solution that yields the change in sample solution appearance or other property expected for stoichiometric equivalence (see <em>equivalence point<\/em>)<\/p>\n<p><strong>equivalence point:\u00a0<\/strong>volume of titrant solution required to react completely with the analyte in a titration analysis; provides a stoichiometric amount of titrant for the sample\u2019s analyte according to the titration reaction<\/p>\n<p><strong>gravimetric analysis:\u00a0<\/strong>quantitative chemical analysis method involving the separation of an analyte from a sample by a physical or chemical process and subsequent mass measurements of the analyte, reaction product, and\/or sample<\/p>\n<p><strong>indicator:\u00a0<\/strong>substance added to the sample in a titration analysis to permit visual detection of the end point<\/p>\n<p><strong>quantitative analysis:\u00a0<\/strong>the determination of the amount or concentration of a substance in a sample<\/p>\n<p><strong>titrant:\u00a0<\/strong>solution containing a known concentration of substance that will react with the analyte in a titration analysis<\/p>\n<p><strong>titration analysis:\u00a0<\/strong>quantitative chemical analysis method that involves measuring the volume of a reactant solution required to completely react with the analyte in a sample<\/p>\n<\/div>\n","protected":false},"author":330,"menu_order":6,"template":"","meta":{"pb_show_title":"on","pb_short_title":"7.5 Quantitative Chemical Analysis","pb_subtitle":"","pb_authors":[],"pb_section_license":"cc-by"},"chapter-type":[],"contributor":[],"license":[50],"class_list":["post-1443","chapter","type-chapter","status-publish","hentry","license-cc-by"],"part":1405,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/chapters\/1443","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/wp\/v2\/users\/330"}],"version-history":[{"count":7,"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/chapters\/1443\/revisions"}],"predecessor-version":[{"id":4770,"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/chapters\/1443\/revisions\/4770"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/parts\/1405"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/chapters\/1443\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/wp\/v2\/media?parent=1443"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/pressbooks\/v2\/chapter-type?post=1443"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/wp\/v2\/contributor?post=1443"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/chem1114langaracollege\/wp-json\/wp\/v2\/license?post=1443"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}