{"id":797,"date":"2021-07-23T09:20:44","date_gmt":"2021-07-23T13:20:44","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/aperrott\/chapter\/hydrolysis-of-salts\/"},"modified":"2022-06-23T09:21:03","modified_gmt":"2022-06-23T13:21:03","slug":"hydrolysis-of-salts","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/aperrott\/chapter\/hydrolysis-of-salts\/","title":{"raw":"14.4 Hydrolysis of Salts","rendered":"14.4 Hydrolysis of Salts"},"content":{"raw":"&nbsp;\r\n<div class=\"textbox textbox--learning-objectives\">\r\n<h3><strong>Learning Objectives<\/strong><\/h3>\r\nBy the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Predict whether a salt solution will be acidic, basic, or neutral<\/li>\r\n \t<li>Calculate the concentrations of the various species in a salt solution<\/li>\r\n \t<li>Describe the acid ionization of hydrated metal ions<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div id=\"fs-idp37481072\" class=\"bc-section section\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>Salts with Acidic Ions<\/strong><\/h3>\r\n<p id=\"fs-idm649972064\">Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt's constituent ions. For example, dissolving ammonium chloride in water results in its dissociation, as described by the equation<\/p>\r\n\r\n<div id=\"fs-idm209439760\" style=\"padding-left: 40px\" data-type=\"equation\">NH<sub>4<\/sub>Cl(<em>s<\/em>) \u2192 NH<sub>4<\/sub><sup>+<\/sup>(<em>aq<\/em>) + Cl<sup>-<\/sup>(<em>aq<\/em>)<\/div>\r\n<p id=\"fs-idm226353632\">The ammonium ion is the conjugate acid of the weak base ammonia, NH<sub>3<\/sub>, and so it will undergo acid ionization (or <em data-effect=\"italics\">acid hydrolysis<\/em>):<\/p>\r\n\r\n<div id=\"fs-idm137491888\" style=\"padding-left: 40px\" data-type=\"equation\">NH<sub>4<\/sub><sup>+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + NH<sub>3<\/sub>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 K<sub>a<\/sub> = K<sub>w<\/sub>\/K<sub>b<\/sub><\/div>\r\n<p id=\"fs-idm238452464\">Since ammonia is a weak base, <em data-effect=\"italics\">K<\/em><sub>b<\/sub> is measurable and <em data-effect=\"italics\">K<\/em><sub>a<\/sub> &gt; 0 (ammonium ion is a weak acid).<\/p>\r\n<p id=\"fs-idm249820848\">The chloride ion is the conjugate base of hydrochloric acid, and so its base ionization (or <em data-effect=\"italics\">base hydrolysis<\/em>) reaction is represented by<\/p>\r\n\r\n<div id=\"fs-idm248062064\" style=\"padding-left: 40px\" data-type=\"equation\">Cl<sup>-<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc HCl(<em>aq<\/em>) + OH<sup>-<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>b<\/sub> = K<sub>w<\/sub>\/K<sub>a<\/sub><\/div>\r\n<p id=\"fs-idm656133776\">Since HCl is a strong acid, <em data-effect=\"italics\">K<\/em><sub>a<\/sub> is immeasurably large and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> \u2248 0 (chloride ions don\u2019t undergo appreciable hydrolysis).<\/p>\r\n<p id=\"fs-idm212824304\">Thus, dissolving ammonium chloride in water yields a solution of weak acid cations (NH<sub>4<\/sub><sup>+<\/sup>) and inert anions (Cl<sup>\u2212<\/sup>), resulting in an acidic solution.<\/p>\r\n\r\n<div id=\"fs-idp38392128\" class=\"textbox textbox--examples\" data-type=\"example\">\r\n<p id=\"fs-idm172853552\"><strong>Calculating the pH of an Acidic Salt Solution <\/strong><\/p>\r\nAniline is an amine that is used to manufacture dyes. It is isolated as anilinium chloride, [C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub>]Cl, a salt prepared by the reaction of the weak base aniline and hydrochloric acid. What is the pH of a 0.233 <em data-effect=\"italics\">M<\/em> solution of anilinium chloride?\r\n<div id=\"fs-idm149245808\" style=\"padding-left: 40px\" data-type=\"equation\">C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup>(aq) + H<sub>2<\/sub>O(l) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>2<\/sub>(<em>aq<\/em>)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm45558496\"><strong>Solution:<\/strong><\/p>\r\nThe <em data-effect=\"italics\">K<\/em><sub>a<\/sub> for anilinium ion is derived from the <em data-effect=\"italics\">K<\/em><sub>b<\/sub> for its conjugate base, aniline (see Appendix H):\r\n<div id=\"fs-idm169067840\" style=\"padding-left: 40px\" data-type=\"equation\"><img class=\"alignnone size-medium wp-image-1881\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-300x44.png\" alt=\"\" width=\"300\" height=\"44\" \/><\/div>\r\n<p id=\"fs-idm169484640\">Using the provided information, an ICE table for this system is prepared:<\/p>\r\n<span id=\"fs-idm4192576\" class=\"scaled-down\" data-type=\"media\" data-alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium ( M ). The second column has the header of \u201cC subscript 6 H subscript 5 N H subscript 3 superscript positive sign plus sign H subscript 2 O equilibrium sign C subscript 6 H subscript 5 N H subscript 2 plus sign H subscript 3 O superscript positive sign.\u201d Under the second column is a subgroup of four columns and three rows. The first column has the following: 0.233, negative x, 0.233 minus x. The second column is blank for all three rows. The third column has the following: 0, positive x, x. The fourth column has the following: approximately 0, positive x, x.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_14_04_steps1_img-1.jpg\" alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium ( M ). The second column has the header of \u201cC subscript 6 H subscript 5 N H subscript 3 superscript positive sign plus sign H subscript 2 O equilibrium sign C subscript 6 H subscript 5 N H subscript 2 plus sign H subscript 3 O superscript positive sign.\u201d Under the second column is a subgroup of four columns and three rows. The first column has the following: 0.233, negative x, 0.233 minus x. The second column is blank for all three rows. The third column has the following: 0, positive x, x. The fourth column has the following: approximately 0, positive x, x.\" data-media-type=\"image\/jpeg\" \/><\/span>\r\n<p id=\"fs-idm175121360\">Substituting these equilibrium concentration terms into the <em data-effect=\"italics\">K<\/em><sub>a<\/sub> expression gives<\/p>\r\n\r\n<div id=\"fs-idm248611472\" style=\"padding-left: 40px\" data-type=\"equation\">K<sub>a<\/sub> = [C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>2<\/sub>][H<sub>3<\/sub>O<sup>+<\/sup>]\/[C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup>]<\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\">2.3 \u00d7 10<sup>\u22125<\/sup> = (<em>x<\/em>)(<em>x<\/em>)\/(0.233-<em>x<\/em>)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm252541328\">Assuming <em data-effect=\"italics\">x<\/em> &lt; 0.05 \u00d7 0.233M, i.e. <em>x<\/em> &lt; 0.0116 M, the equation is simplified and solved for <em data-effect=\"italics\">x<\/em>:<\/p>\r\n\r\n<div id=\"fs-idm204343104\" style=\"padding-left: 40px\" data-type=\"equation\">2.3 \u00d7 10<sup>\u22125<\/sup> = <em>x<\/em><sup>2<\/sup>\/0.233<\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\"><em>x<\/em> = 0.0023 M\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 ASSUMPTION VALID<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm228289760\">The ICE table defines<em> x<\/em> as the hydronium ion molarity, and so the pH is computed as<\/p>\r\n\r\n<div id=\"fs-idm247349056\" style=\"padding-left: 40px\" data-type=\"equation\">pH = -log[H<sub>3<\/sub>O<sup>+<\/sup>] = \u2212log(0.0023 M) = 2.64<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm156700000\"><strong>Check Your Learning:<\/strong><\/p>\r\nWhat is the hydronium ion concentration in a 0.100-<em data-effect=\"italics\">M<\/em> solution of ammonium nitrate, NH<sub>4<\/sub>NO<sub>3<\/sub>, a salt composed of the ions NH<sub>4<\/sub><sup>+<\/sup> and NO<sub>3<\/sub><sup>\u2212<\/sup>. Which is the stronger acid, C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup> or NH<sub>4<\/sub><sup>+<\/sup>?\r\n\r\n&nbsp;\r\n<div id=\"fs-idm54595904\" data-type=\"note\">\r\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\r\n<p id=\"fs-idp43419152\">[H<sub>3<\/sub>O<sup>+<\/sup>] = 7.5 \u00d7 10<sup>\u22126<\/sup><em data-effect=\"italics\">M<\/em>; C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup> is the stronger acid.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"fs-idm135179984\" class=\"bc-section section\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>Salts with Basic Ions<\/strong><\/h3>\r\n<p id=\"fs-idm119438896\">As another example, consider dissolving sodium acetate in water:<\/p>\r\n\r\n<div id=\"fs-idm243373152\" style=\"padding-left: 40px\" data-type=\"equation\">NaCH<sub>3<\/sub>CO<sub>2<\/sub>(<em>s<\/em>) \u2192 Na<sup>+<\/sup>(<em>aq<\/em>) + CH<sub>3<\/sub>CO<sub>2<\/sub><sup>-<\/sup>(<em>aq<\/em>)<\/div>\r\n<p id=\"fs-idm237096048\">The sodium ion does not undergo appreciable acid or base ionization and has no effect on the solution pH. This may seem obvious from the ion's formula, which indicates no hydrogen or oxygen atoms, but some dissolved metal ions function as weak acids, as addressed later in this section.<\/p>\r\n<p id=\"fs-idm248142864\">The acetate ion, CH<sub>3<\/sub>CO<sub>2<\/sub><sup>-<\/sup>, is the conjugate base of acetic acid, CH<sub>3<\/sub>CO<sub>2<\/sub>H, and so its base ionization (or <em data-effect=\"italics\">base hydrolysis<\/em>) reaction is represented by<\/p>\r\n\r\n<div id=\"fs-idm641525520\" style=\"padding-left: 40px\" data-type=\"equation\">CH<sub>3<\/sub>CO<sub>2<\/sub><sup>-<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc CH<sub>3<\/sub>CO<sub>2<\/sub>H(<em>aq<\/em>) + OH<sup>-<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 K<sub>b<\/sub> = K<sub>w<\/sub>\/K<sub>a<\/sub><\/div>\r\n<p id=\"fs-idm249385760\">Because acetic acid is a weak acid, its <em data-effect=\"italics\">K<\/em><sub>a<\/sub> is measurable and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> &gt; 0 (acetate ion is a weak base).<\/p>\r\n<p id=\"fs-idm248895632\">Dissolving sodium acetate in water yields a solution of inert cations (Na<sup>+<\/sup>) and weak base anions (CH<sub>3<\/sub>CO<sub>2<\/sub><sup>-<\/sup>), resulting in a basic solution.<\/p>\r\n\r\n<div id=\"fs-idp37320880\" class=\"textbox textbox--examples\" data-type=\"example\">\r\n<p id=\"fs-idm168517392\"><strong>Equilibrium in a Solution of a Salt of a Weak Acid and a Strong Base <\/strong><\/p>\r\nDetermine the acetic acid concentration in a solution with [CH<sub>3<\/sub>CO<sub>2<\/sub><sup>-<\/sup>] = 0.050 M and [OH<sup>\u2212<\/sup>] = 2.5 \u00d7 10<sup>\u22126<\/sup><em data-effect=\"italics\">M<\/em> at equilibrium.\r\n\r\nThe reaction is:\r\n<div id=\"fs-idm148031584\" style=\"padding-left: 40px\" data-type=\"equation\">CH<sub>3<\/sub>CO<sub>2<\/sub><sup>-<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc CH<sub>3<\/sub>CO<sub>2<\/sub>H(<em>aq<\/em>) + OH<sup>\u2212<\/sup>(aq)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm2736464\"><strong>Solution:<\/strong><\/p>\r\nThe provided equilibrium concentrations and a value for the equilibrium constant will permit calculation of the missing equilibrium concentration. The process in question is the base ionization of acetate ion, for which\r\n<p style=\"padding-left: 40px\"><img class=\"alignnone wp-image-1891\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-300x25.png\" alt=\"\" width=\"456\" height=\"38\" \/><\/p>\r\n<p id=\"fs-idm121126768\">Substituting the available values into the <em data-effect=\"italics\">K<\/em><sub>b<\/sub> expression gives<\/p>\r\n\r\n<div id=\"fs-idm218140928\" style=\"padding-left: 40px\" data-type=\"equation\"><img class=\"alignnone size-medium wp-image-1892\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-300x49.png\" alt=\"\" width=\"300\" height=\"49\" \/><\/div>\r\n<div style=\"padding-left: 40px\" data-type=\"equation\"><img class=\"alignnone size-medium wp-image-1893\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-300x48.png\" alt=\"\" width=\"300\" height=\"48\" \/><\/div>\r\n<p id=\"fs-idm45670544\">Solving the above equation for the acetic acid molarity yields [CH<sub>3<\/sub>CO<sub>2<\/sub>H] = 1.1 \u00d7 10<sup>\u22125<\/sup><em data-effect=\"italics\">M<\/em>.<\/p>\r\n<p id=\"fs-idm54917312\"><strong>Check Your Learning:<\/strong><\/p>\r\nWhat is the pH of a 0.083-<em data-effect=\"italics\">M<\/em> solution of NaCN?\r\n\r\n&nbsp;\r\n<div id=\"fs-idm95967568\" data-type=\"note\">\r\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\r\n<p id=\"fs-idm7663712\">11.11<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"fs-idm81229520\" class=\"bc-section section\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>Salts with Acidic and Basic Ions<\/strong><\/h3>\r\n<p id=\"fs-idp31152\">Some salts are composed of both acidic and basic ions, and so the pH of their solutions will depend on the relative strengths of these two species. Likewise, some salts contain a single ion that is amphiprotic, and so the relative strengths of this ion\u2019s acid and base character will determine its effect on solution pH. For both types of salts, a comparison of the <em data-effect=\"italics\">K<\/em><sub>a<\/sub> and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> values allows prediction of the solution\u2019s acid-base status, as illustrated in the following example exercise.<\/p>\r\n\r\n<div id=\"fs-idm161229856\" class=\"textbox textbox--examples\" data-type=\"example\">\r\n<p id=\"fs-idm219032992\"><strong>Determining the Acidic or Basic Nature of Salts <\/strong><\/p>\r\nDetermine whether aqueous solutions of the following salts are acidic, basic, or neutral:\r\n<p id=\"fs-idm55604816\">(a) KBr<\/p>\r\n<p id=\"fs-idp65280880\">(b) NaHCO<sub>3<\/sub><\/p>\r\n<p id=\"fs-idm82359664\">(c) Na<sub>2<\/sub>HPO<sub>4<\/sub><\/p>\r\n<p id=\"fs-idm18348400\">(d) NH<sub>4<\/sub>F<\/p>\r\n<p id=\"fs-idm117618912\"><strong>Solution:<\/strong><\/p>\r\nConsider each of the ions separately in terms of its effect on the pH of the solution, as shown here:\r\n<p id=\"fs-idm56643648\">(a) The K<sup>+<\/sup> cation is inert and will not affect pH. The bromide ion is the conjugate base of a strong acid, and so it is of negligible base strength (no appreciable base ionization). The solution is neutral.<\/p>\r\n<p id=\"fs-idm168102384\">(b) The Na<sup>+<\/sup> cation is inert and will not affect the pH of the solution; while the HCO<sub>3<\/sub><sup>\u2212<\/sup> anion is amphiprotic. The <em data-effect=\"italics\">K<\/em><sub>a<\/sub> of HCO<sub>3<\/sub><sup>\u2212<\/sup> is 4.7 \u00d7 10<sup>\u221211<\/sup>, and its <em data-effect=\"italics\">K<\/em><sub>b<\/sub> is <img class=\"alignnone wp-image-1888\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f-300x51.png\" alt=\"\" width=\"176\" height=\"30\" \/><\/p>\r\n<p id=\"fs-idm98756192\">Since <em data-effect=\"italics\">K<\/em><sub>b<\/sub> &gt;&gt; <em data-effect=\"italics\">K<\/em><sub>a<\/sub>, the solution is basic.<\/p>\r\n<p id=\"fs-idp9214400\">(c) The Na<sup>+<\/sup> cation is inert and will not affect the pH of the solution, while the HPO<sub>4<\/sub><sup>2<\/sup><sup>\u2212<\/sup> anion is amphiprotic. The <em data-effect=\"italics\">K<\/em><sub>a<\/sub> of HPO<sub>4<\/sub><sup>2<\/sup><sup>\u2212<\/sup> is 4.2 \u00d7 10<sup>\u221213<\/sup>,<\/p>\r\n<p id=\"fs-idp53880096\">and its <em data-effect=\"italics\">K<\/em><sub>b<\/sub> is <img class=\"alignnone wp-image-1894\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k-300x47.png\" alt=\"\" width=\"160\" height=\"25\" \/> Because <em data-effect=\"italics\">K<\/em><sub>b<\/sub> &gt;&gt; <em data-effect=\"italics\">K<\/em><sub>a<\/sub>, the solution is basic.<\/p>\r\n<p id=\"fs-idp10452272\">(d) The NH<sub>4<\/sub><sup>+<\/sup> ion is acidic (see above discussion) and the F<sup>\u2212<\/sup> ion is basic (conjugate base of the weak acid HF). Comparing the two ionization constants: <em data-effect=\"italics\">K<\/em><sub>a<\/sub> of NH<sub>4<\/sub><sup>+<\/sup> is 5.6 \u00d7 10<sup>\u221210<\/sup> and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> of F<sup>\u2212<\/sup> is 1.4 \u00d7 10<sup>\u221211<\/sup>, so the solution is acidic, since <em data-effect=\"italics\">K<\/em><sub>a<\/sub> &gt; <em data-effect=\"italics\">K<\/em><sub>b<\/sub>.<\/p>\r\n<p id=\"fs-idm140849264\"><strong>Check Your Learning:<\/strong><\/p>\r\nDetermine whether aqueous solutions of the following salts are acidic, basic, or neutral:\r\n<p id=\"fs-idm15098896\">(a) K<sub>2<\/sub>CO<sub>3<\/sub><\/p>\r\n<p id=\"fs-idm75225328\">(b) CaCl<sub>2<\/sub><\/p>\r\n<p id=\"fs-idm290933120\">(c) KH<sub>2<\/sub>PO<sub>4<\/sub><\/p>\r\n<p id=\"fs-idm223869584\">(d) (NH<sub>4<\/sub>)<sub>2<\/sub>CO<sub>3<\/sub><\/p>\r\n&nbsp;\r\n<div id=\"fs-idm42020240\" data-type=\"note\">\r\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\r\n<p id=\"fs-idm5299888\">(a) basic; (b) neutral; (c) acidic; (d) basic<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"fs-idm108915120\" class=\"bc-section section\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>The Ionization of Hydrated Metal Ions<\/strong><\/h3>\r\n<p id=\"fs-idm252144288\">Unlike the group 1 and 2 metal ions of the preceding examples (Na<sup>+<\/sup>, Ca<sup>2+<\/sup>, etc.), some metal ions function as acids in aqueous solutions. These ions are not just loosely solvated by water molecules when dissolved, instead they are covalently bonded to a fixed number of water molecules to yield a complex ion. As an example, the dissolution of aluminum nitrate in water is typically represented as<\/p>\r\n&nbsp;\r\n<div id=\"fs-idm253215984\" style=\"padding-left: 40px\" data-type=\"equation\">Al(NO<sub>3<\/sub>)<sub>3<\/sub>(<em>s<\/em>) \u2192 Al<sup>3+<\/sup>(<em>aq<\/em>) + 3NO<sub>3<\/sub><sup>-<\/sup>(<em>aq<\/em>)<\/div>\r\n<p id=\"fs-idm252419632\">However, the aluminum(III) ion actually reacts with six water molecules to form a stable complex ion, and so the more explicit representation of the dissolution process is<\/p>\r\n\r\n<div id=\"fs-idm117678832\" style=\"padding-left: 40px\" data-type=\"equation\">Al(NO<sub>3<\/sub>)<sub>3<\/sub>(<em>s<\/em>)\u00a0 + 6H<sub>2<\/sub>O(l) \u2192 Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + 3NO<sub>3<\/sub><sup>-<\/sup>(<em>aq<\/em>)<\/div>\r\n<p id=\"fs-idm251913856\">As shown in <a class=\"autogenerated-content\" href=\"#CNX_Chem_14_04_hydronium\">(Figure)<\/a>, the Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup> ions involve bonds between a central Al atom and the O atoms of the six water molecules. Consequently, the bonded water molecules' O\u2013H bonds are more polar than in nonbonded water molecules, making the bonded molecules more prone to donation of a hydrogen ion:<\/p>\r\n\r\n<div id=\"fs-idm108244016\" style=\"padding-left: 40px\" data-type=\"equation\">Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Al(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 1.4 \u00d7 10<sup>-5<\/sup><\/div>\r\n<div id=\"fs-idm46178496\" data-type=\"equation\"><\/div>\r\n<div id=\"CNX_Chem_14_04_hydronium\" class=\"scaled-down\">\r\n<div class=\"bc-figcaption figcaption\">When an aluminum ion reacts with water, the hydrated aluminum ion becomes a weak acid.<\/div>\r\n<span id=\"fs-idp82299440\" data-type=\"media\" data-alt=\"A reaction is shown using ball and stick models. On the left, inside brackets with a superscript of 3 plus outside to the right is structure labeled \u201c[ A l ( H subscript 2 O ) subscript 6 ] superscript 3 plus.\u201d Inside the brackets is s central grey atom to which 6 red atoms are bonded in an arrangement that distributes them evenly about the central grey atom. Each red atom has two smaller white atoms attached in a forked or bent arrangement. Outside the brackets to the right is a space-filling model that includes a red central sphere with two smaller white spheres attached in a bent arrangement. Beneath this structure is the label \u201cH subscript 2 O.\u201d A double sided arrow follows. Another set of brackets follows to the right of the arrows which have a superscript of two plus outside to the right. The structure inside the brackets is similar to that on the left, except a white atom is removed from the structure. The label below is also changed to \u201c[ A l ( H subscript 2 O ) subscript 5 O H ] superscript 2 plus.\u201d To the right of this structure and outside the brackets is a space filling model with a central red sphere to which 3 smaller white spheres are attached. This structure is labeled \u201cH subscript 3 O superscript plus.\u201d\"><img src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_14_04_hydronium-1.jpg\" alt=\"A reaction is shown using ball and stick models. On the left, inside brackets with a superscript of 3 plus outside to the right is structure labeled \u201c[ A l ( H subscript 2 O ) subscript 6 ] superscript 3 plus.\u201d Inside the brackets is s central grey atom to which 6 red atoms are bonded in an arrangement that distributes them evenly about the central grey atom. Each red atom has two smaller white atoms attached in a forked or bent arrangement. Outside the brackets to the right is a space-filling model that includes a red central sphere with two smaller white spheres attached in a bent arrangement. Beneath this structure is the label \u201cH subscript 2 O.\u201d A double sided arrow follows. Another set of brackets follows to the right of the arrows which have a superscript of two plus outside to the right. The structure inside the brackets is similar to that on the left, except a white atom is removed from the structure. The label below is also changed to \u201c[ A l ( H subscript 2 O ) subscript 5 O H ] superscript 2 plus.\u201d To the right of this structure and outside the brackets is a space filling model with a central red sphere to which 3 smaller white spheres are attached. This structure is labeled \u201cH subscript 3 O superscript plus.\u201d\" data-media-type=\"image\/jpeg\" \/><\/span>\r\n\r\n<\/div>\r\n<p id=\"fs-idm167123728\">Aside from the alkali metals (group 1) and some alkaline earth metals (group 2), most other metal ions will undergo acid ionization to some extent when dissolved in water. The acid strength of these complex ions typically increases with increasing charge and decreasing size of the metal ions. The first-step acid ionization equations for a few other acidic metal ions are shown below:<\/p>\r\n\r\n<div id=\"fs-idp56836016\" style=\"padding-left: 40px\" data-type=\"equation\">Fe(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Fe(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 6 \u00d7 10<sup>-3<\/sup><\/div>\r\n<div id=\"fs-idm116986352\" style=\"padding-left: 40px\" data-type=\"equation\">Cu(H<sub>2<\/sub>O)<sub>6<\/sub><sup>2+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Cu(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 3 \u00d7 10<sup>-8<\/sup><\/div>\r\n<div id=\"fs-idm166964496\" data-type=\"equation\"><\/div>\r\n<div id=\"fs-idm171178400\" class=\"textbox textbox--examples\" data-type=\"example\">\r\n<p id=\"fs-idm122608832\"><strong>Hydrolysis of [Al(H<sub>2<\/sub>O)<sub>6<\/sub>]<sup>3+<\/sup> <\/strong><\/p>\r\nCalculate the pH of a 0.10-<em data-effect=\"italics\">M<\/em> solution of aluminum chloride, which dissolves completely to give the hydrated aluminum ion, Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>, in solution.\r\n<p id=\"fs-idp112354272\"><strong>Solution:<\/strong><\/p>\r\nThe equation for the reaction and <em data-effect=\"italics\">K<\/em><sub>a<\/sub> are:<span data-type=\"newline\">\r\n<\/span>\r\n<div id=\"fs-idm224297104\" data-type=\"equation\">Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Al(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 1.4 \u00d7 10<sup>-5<\/sup><\/div>\r\n<span data-type=\"newline\">\r\n<\/span> An ICE table with the provided information is<span data-type=\"newline\">\r\n<\/span>\r\n\r\n<span id=\"fs-idm136267808\" data-type=\"media\" data-alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium concentration ( M ). The second column has the header of \u201cA l ( H subscript 2 O ) subscript 6 superscript 3 positive sign plus H subscript 2 O equilibrium arrow H subscript 3 O superscript positive sign plus A l ( H subscript 2 O ) subscript 5 ( O H ) superscript 2 positive sign.\u201d Under the second column is a subgroup of three columns and three rows. The first column has the following: 0.10, negative x, 0.10 minus x. The second column has the following: approximately 0, positive x, x. The third column has the following: 0, positive x, x.\"><img src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_14_04_ICETable13_img-1.jpg\" alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium concentration ( M ). The second column has the header of \u201cA l ( H subscript 2 O ) subscript 6 superscript 3 positive sign plus H subscript 2 O equilibrium arrow H subscript 3 O superscript positive sign plus A l ( H subscript 2 O ) subscript 5 ( O H ) superscript 2 positive sign.\u201d Under the second column is a subgroup of three columns and three rows. The first column has the following: 0.10, negative x, 0.10 minus x. The second column has the following: approximately 0, positive x, x. The third column has the following: 0, positive x, x.\" data-media-type=\"image\/jpeg\" \/><\/span>\r\n\r\n<span data-type=\"newline\">\r\n<\/span> Substituting the expressions for the equilibrium concentrations into the equation for the ionization constant yields:<span data-type=\"newline\">\r\n<\/span>\r\n<div id=\"fs-idm98439712\" style=\"padding-left: 40px\" data-type=\"equation\"><img class=\"alignnone wp-image-1897\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-300x188.png\" alt=\"\" width=\"211\" height=\"132\" \/><\/div>\r\n<span data-type=\"newline\">\r\n<\/span> Assuming <em data-effect=\"italics\">x<\/em> &lt; 0.05 \u00d7 0.10 M, i.e. <em data-effect=\"italics\">x<\/em> &lt; 0.0050 M and solving the simplified equation gives:<span data-type=\"newline\">\r\n<\/span>\r\n<div id=\"fs-idp4666608\" style=\"padding-left: 40px\" data-type=\"equation\"><em>x<\/em> = 1.2 \u00d7 10<sup>-3<\/sup> M\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 ASSUMPTION VALID<\/div>\r\n<span data-type=\"newline\">\r\n<\/span> The ICE table defined <em data-effect=\"italics\">x<\/em> as equal to the hydronium ion concentration, and so the pH is calculated to be<span data-type=\"newline\">\r\n<\/span>\r\n<div id=\"fs-idm156052944\" style=\"padding-left: 40px\" data-type=\"equation\">[H<sub>3<\/sub>O<sup>+<\/sup>] = <em>x<\/em> = 1.2 \u00d7 10<sup>-3<\/sup> M<\/div>\r\n<span data-type=\"newline\">\u00a0<\/span>\r\n<div id=\"fs-idm161964736\" style=\"padding-left: 40px\" data-type=\"equation\">pH = \u2212log[H<sub>3<\/sub>O<sup>+<\/sup>] = 2.92\u00a0 \u00a0 \u00a0(an acidic solution)<\/div>\r\n<div data-type=\"equation\"><\/div>\r\n<p id=\"fs-idm175924752\"><strong>Check Your Learning:<\/strong><\/p>\r\nWhat is [Al(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>] in a 0.15-<em data-effect=\"italics\">M<\/em> solution of Al(NO<sub>3<\/sub>)<sub>3<\/sub> that contains enough of the strong acid HNO<sub>3<\/sub> to bring [H<sub>3<\/sub>O<sup>+<\/sup>] to 0.10 <em data-effect=\"italics\">M<\/em>?\r\n\r\n&nbsp;\r\n<div id=\"fs-idm38454832\" data-type=\"note\">\r\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\r\n<p id=\"fs-idp86512272\">2.1 \u00d7 10<sup>\u22125<\/sup><em data-effect=\"italics\">M<\/em><\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"fs-idm180137840\" class=\"summary\" data-depth=\"1\">\r\n<h3 data-type=\"title\"><strong>Key Concepts and Summary<\/strong><\/h3>\r\n<p id=\"fs-idp3314288\">The ions composing salts may possess acidic or basic character, ionizing when dissolved in water to yield acidic or basic solutions. Acidic cations are typically the conjugate partners of weak bases, and basic anions are the conjugate partners of weak acids. Many metal ions bond to water molecules when dissolved to yield complex ions that may function as acids.<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-idm46050816\" class=\"exercises\" data-depth=\"1\">\r\n<div id=\"fs-idm1823584\" data-type=\"exercise\">\r\n<div id=\"fs-idm138043888\" data-type=\"problem\">\r\n<p id=\"fs-idp30279488\"><\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>","rendered":"<p>&nbsp;<\/p>\n<div class=\"textbox textbox--learning-objectives\">\n<h3><strong>Learning Objectives<\/strong><\/h3>\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Predict whether a salt solution will be acidic, basic, or neutral<\/li>\n<li>Calculate the concentrations of the various species in a salt solution<\/li>\n<li>Describe the acid ionization of hydrated metal ions<\/li>\n<\/ul>\n<\/div>\n<div id=\"fs-idp37481072\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>Salts with Acidic Ions<\/strong><\/h3>\n<p id=\"fs-idm649972064\">Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt&#8217;s constituent ions. For example, dissolving ammonium chloride in water results in its dissociation, as described by the equation<\/p>\n<div id=\"fs-idm209439760\" style=\"padding-left: 40px\" data-type=\"equation\">NH<sub>4<\/sub>Cl(<em>s<\/em>) \u2192 NH<sub>4<\/sub><sup>+<\/sup>(<em>aq<\/em>) + Cl<sup>&#8211;<\/sup>(<em>aq<\/em>)<\/div>\n<p id=\"fs-idm226353632\">The ammonium ion is the conjugate acid of the weak base ammonia, NH<sub>3<\/sub>, and so it will undergo acid ionization (or <em data-effect=\"italics\">acid hydrolysis<\/em>):<\/p>\n<div id=\"fs-idm137491888\" style=\"padding-left: 40px\" data-type=\"equation\">NH<sub>4<\/sub><sup>+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + NH<sub>3<\/sub>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 K<sub>a<\/sub> = K<sub>w<\/sub>\/K<sub>b<\/sub><\/div>\n<p id=\"fs-idm238452464\">Since ammonia is a weak base, <em data-effect=\"italics\">K<\/em><sub>b<\/sub> is measurable and <em data-effect=\"italics\">K<\/em><sub>a<\/sub> &gt; 0 (ammonium ion is a weak acid).<\/p>\n<p id=\"fs-idm249820848\">The chloride ion is the conjugate base of hydrochloric acid, and so its base ionization (or <em data-effect=\"italics\">base hydrolysis<\/em>) reaction is represented by<\/p>\n<div id=\"fs-idm248062064\" style=\"padding-left: 40px\" data-type=\"equation\">Cl<sup>&#8211;<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc HCl(<em>aq<\/em>) + OH<sup>&#8211;<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>b<\/sub> = K<sub>w<\/sub>\/K<sub>a<\/sub><\/div>\n<p id=\"fs-idm656133776\">Since HCl is a strong acid, <em data-effect=\"italics\">K<\/em><sub>a<\/sub> is immeasurably large and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> \u2248 0 (chloride ions don\u2019t undergo appreciable hydrolysis).<\/p>\n<p id=\"fs-idm212824304\">Thus, dissolving ammonium chloride in water yields a solution of weak acid cations (NH<sub>4<\/sub><sup>+<\/sup>) and inert anions (Cl<sup>\u2212<\/sup>), resulting in an acidic solution.<\/p>\n<div id=\"fs-idp38392128\" class=\"textbox textbox--examples\" data-type=\"example\">\n<p id=\"fs-idm172853552\"><strong>Calculating the pH of an Acidic Salt Solution <\/strong><\/p>\n<p>Aniline is an amine that is used to manufacture dyes. It is isolated as anilinium chloride, [C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub>]Cl, a salt prepared by the reaction of the weak base aniline and hydrochloric acid. What is the pH of a 0.233 <em data-effect=\"italics\">M<\/em> solution of anilinium chloride?<\/p>\n<div id=\"fs-idm149245808\" style=\"padding-left: 40px\" data-type=\"equation\">C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup>(aq) + H<sub>2<\/sub>O(l) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>2<\/sub>(<em>aq<\/em>)<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm45558496\"><strong>Solution:<\/strong><\/p>\n<p>The <em data-effect=\"italics\">K<\/em><sub>a<\/sub> for anilinium ion is derived from the <em data-effect=\"italics\">K<\/em><sub>b<\/sub> for its conjugate base, aniline (see Appendix H):<\/p>\n<div id=\"fs-idm169067840\" style=\"padding-left: 40px\" data-type=\"equation\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-1881\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-300x44.png\" alt=\"\" width=\"300\" height=\"44\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-300x44.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-1024x150.png 1024w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-768x112.png 768w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-65x10.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-225x33.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a-350x51.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4a.png 1074w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/div>\n<p id=\"fs-idm169484640\">Using the provided information, an ICE table for this system is prepared:<\/p>\n<p><span id=\"fs-idm4192576\" class=\"scaled-down\" data-type=\"media\" data-alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium ( M ). The second column has the header of \u201cC subscript 6 H subscript 5 N H subscript 3 superscript positive sign plus sign H subscript 2 O equilibrium sign C subscript 6 H subscript 5 N H subscript 2 plus sign H subscript 3 O superscript positive sign.\u201d Under the second column is a subgroup of four columns and three rows. The first column has the following: 0.233, negative x, 0.233 minus x. The second column is blank for all three rows. The third column has the following: 0, positive x, x. The fourth column has the following: approximately 0, positive x, x.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_14_04_steps1_img-1.jpg\" alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium ( M ). The second column has the header of \u201cC subscript 6 H subscript 5 N H subscript 3 superscript positive sign plus sign H subscript 2 O equilibrium sign C subscript 6 H subscript 5 N H subscript 2 plus sign H subscript 3 O superscript positive sign.\u201d Under the second column is a subgroup of four columns and three rows. The first column has the following: 0.233, negative x, 0.233 minus x. The second column is blank for all three rows. The third column has the following: 0, positive x, x. The fourth column has the following: approximately 0, positive x, x.\" data-media-type=\"image\/jpeg\" \/><\/span><\/p>\n<p id=\"fs-idm175121360\">Substituting these equilibrium concentration terms into the <em data-effect=\"italics\">K<\/em><sub>a<\/sub> expression gives<\/p>\n<div id=\"fs-idm248611472\" style=\"padding-left: 40px\" data-type=\"equation\">K<sub>a<\/sub> = [C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>2<\/sub>][H<sub>3<\/sub>O<sup>+<\/sup>]\/[C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup>]<\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\">2.3 \u00d7 10<sup>\u22125<\/sup> = (<em>x<\/em>)(<em>x<\/em>)\/(0.233-<em>x<\/em>)<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm252541328\">Assuming <em data-effect=\"italics\">x<\/em> &lt; 0.05 \u00d7 0.233M, i.e. <em>x<\/em> &lt; 0.0116 M, the equation is simplified and solved for <em data-effect=\"italics\">x<\/em>:<\/p>\n<div id=\"fs-idm204343104\" style=\"padding-left: 40px\" data-type=\"equation\">2.3 \u00d7 10<sup>\u22125<\/sup> = <em>x<\/em><sup>2<\/sup>\/0.233<\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\"><em>x<\/em> = 0.0023 M\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 ASSUMPTION VALID<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm228289760\">The ICE table defines<em> x<\/em> as the hydronium ion molarity, and so the pH is computed as<\/p>\n<div id=\"fs-idm247349056\" style=\"padding-left: 40px\" data-type=\"equation\">pH = -log[H<sub>3<\/sub>O<sup>+<\/sup>] = \u2212log(0.0023 M) = 2.64<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm156700000\"><strong>Check Your Learning:<\/strong><\/p>\n<p>What is the hydronium ion concentration in a 0.100-<em data-effect=\"italics\">M<\/em> solution of ammonium nitrate, NH<sub>4<\/sub>NO<sub>3<\/sub>, a salt composed of the ions NH<sub>4<\/sub><sup>+<\/sup> and NO<sub>3<\/sub><sup>\u2212<\/sup>. Which is the stronger acid, C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup> or NH<sub>4<\/sub><sup>+<\/sup>?<\/p>\n<p>&nbsp;<\/p>\n<div id=\"fs-idm54595904\" data-type=\"note\">\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\n<p id=\"fs-idp43419152\">[H<sub>3<\/sub>O<sup>+<\/sup>] = 7.5 \u00d7 10<sup>\u22126<\/sup><em data-effect=\"italics\">M<\/em>; C<sub>6<\/sub>H<sub>5<\/sub>NH<sub>3<\/sub><sup>+<\/sup> is the stronger acid.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-idm135179984\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>Salts with Basic Ions<\/strong><\/h3>\n<p id=\"fs-idm119438896\">As another example, consider dissolving sodium acetate in water:<\/p>\n<div id=\"fs-idm243373152\" style=\"padding-left: 40px\" data-type=\"equation\">NaCH<sub>3<\/sub>CO<sub>2<\/sub>(<em>s<\/em>) \u2192 Na<sup>+<\/sup>(<em>aq<\/em>) + CH<sub>3<\/sub>CO<sub>2<\/sub><sup>&#8211;<\/sup>(<em>aq<\/em>)<\/div>\n<p id=\"fs-idm237096048\">The sodium ion does not undergo appreciable acid or base ionization and has no effect on the solution pH. This may seem obvious from the ion&#8217;s formula, which indicates no hydrogen or oxygen atoms, but some dissolved metal ions function as weak acids, as addressed later in this section.<\/p>\n<p id=\"fs-idm248142864\">The acetate ion, CH<sub>3<\/sub>CO<sub>2<\/sub><sup>&#8211;<\/sup>, is the conjugate base of acetic acid, CH<sub>3<\/sub>CO<sub>2<\/sub>H, and so its base ionization (or <em data-effect=\"italics\">base hydrolysis<\/em>) reaction is represented by<\/p>\n<div id=\"fs-idm641525520\" style=\"padding-left: 40px\" data-type=\"equation\">CH<sub>3<\/sub>CO<sub>2<\/sub><sup>&#8211;<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc CH<sub>3<\/sub>CO<sub>2<\/sub>H(<em>aq<\/em>) + OH<sup>&#8211;<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 K<sub>b<\/sub> = K<sub>w<\/sub>\/K<sub>a<\/sub><\/div>\n<p id=\"fs-idm249385760\">Because acetic acid is a weak acid, its <em data-effect=\"italics\">K<\/em><sub>a<\/sub> is measurable and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> &gt; 0 (acetate ion is a weak base).<\/p>\n<p id=\"fs-idm248895632\">Dissolving sodium acetate in water yields a solution of inert cations (Na<sup>+<\/sup>) and weak base anions (CH<sub>3<\/sub>CO<sub>2<\/sub><sup>&#8211;<\/sup>), resulting in a basic solution.<\/p>\n<div id=\"fs-idp37320880\" class=\"textbox textbox--examples\" data-type=\"example\">\n<p id=\"fs-idm168517392\"><strong>Equilibrium in a Solution of a Salt of a Weak Acid and a Strong Base <\/strong><\/p>\n<p>Determine the acetic acid concentration in a solution with [CH<sub>3<\/sub>CO<sub>2<\/sub><sup>&#8211;<\/sup>] = 0.050 M and [OH<sup>\u2212<\/sup>] = 2.5 \u00d7 10<sup>\u22126<\/sup><em data-effect=\"italics\">M<\/em> at equilibrium.<\/p>\n<p>The reaction is:<\/p>\n<div id=\"fs-idm148031584\" style=\"padding-left: 40px\" data-type=\"equation\">CH<sub>3<\/sub>CO<sub>2<\/sub><sup>&#8211;<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc CH<sub>3<\/sub>CO<sub>2<\/sub>H(<em>aq<\/em>) + OH<sup>\u2212<\/sup>(aq)<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm2736464\"><strong>Solution:<\/strong><\/p>\n<p>The provided equilibrium concentrations and a value for the equilibrium constant will permit calculation of the missing equilibrium concentration. The process in question is the base ionization of acetate ion, for which<\/p>\n<p style=\"padding-left: 40px\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-1891\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-300x25.png\" alt=\"\" width=\"456\" height=\"38\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-300x25.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-1024x84.png 1024w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-768x63.png 768w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-1536x126.png 1536w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-65x5.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-225x18.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h-350x29.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4h.png 1864w\" sizes=\"auto, (max-width: 456px) 100vw, 456px\" \/><\/p>\n<p id=\"fs-idm121126768\">Substituting the available values into the <em data-effect=\"italics\">K<\/em><sub>b<\/sub> expression gives<\/p>\n<div id=\"fs-idm218140928\" style=\"padding-left: 40px\" data-type=\"equation\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-1892\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-300x49.png\" alt=\"\" width=\"300\" height=\"49\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-300x49.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-1024x166.png 1024w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-768x124.png 768w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-65x11.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-225x36.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i-350x57.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4i.png 1043w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/div>\n<div style=\"padding-left: 40px\" data-type=\"equation\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-1893\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-300x48.png\" alt=\"\" width=\"300\" height=\"48\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-300x48.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-1024x164.png 1024w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-768x123.png 768w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-65x10.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-225x36.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j-350x56.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4j.png 1033w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/div>\n<p id=\"fs-idm45670544\">Solving the above equation for the acetic acid molarity yields [CH<sub>3<\/sub>CO<sub>2<\/sub>H] = 1.1 \u00d7 10<sup>\u22125<\/sup><em data-effect=\"italics\">M<\/em>.<\/p>\n<p id=\"fs-idm54917312\"><strong>Check Your Learning:<\/strong><\/p>\n<p>What is the pH of a 0.083-<em data-effect=\"italics\">M<\/em> solution of NaCN?<\/p>\n<p>&nbsp;<\/p>\n<div id=\"fs-idm95967568\" data-type=\"note\">\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\n<p id=\"fs-idm7663712\">11.11<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-idm81229520\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>Salts with Acidic and Basic Ions<\/strong><\/h3>\n<p id=\"fs-idp31152\">Some salts are composed of both acidic and basic ions, and so the pH of their solutions will depend on the relative strengths of these two species. Likewise, some salts contain a single ion that is amphiprotic, and so the relative strengths of this ion\u2019s acid and base character will determine its effect on solution pH. For both types of salts, a comparison of the <em data-effect=\"italics\">K<\/em><sub>a<\/sub> and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> values allows prediction of the solution\u2019s acid-base status, as illustrated in the following example exercise.<\/p>\n<div id=\"fs-idm161229856\" class=\"textbox textbox--examples\" data-type=\"example\">\n<p id=\"fs-idm219032992\"><strong>Determining the Acidic or Basic Nature of Salts <\/strong><\/p>\n<p>Determine whether aqueous solutions of the following salts are acidic, basic, or neutral:<\/p>\n<p id=\"fs-idm55604816\">(a) KBr<\/p>\n<p id=\"fs-idp65280880\">(b) NaHCO<sub>3<\/sub><\/p>\n<p id=\"fs-idm82359664\">(c) Na<sub>2<\/sub>HPO<sub>4<\/sub><\/p>\n<p id=\"fs-idm18348400\">(d) NH<sub>4<\/sub>F<\/p>\n<p id=\"fs-idm117618912\"><strong>Solution:<\/strong><\/p>\n<p>Consider each of the ions separately in terms of its effect on the pH of the solution, as shown here:<\/p>\n<p id=\"fs-idm56643648\">(a) The K<sup>+<\/sup> cation is inert and will not affect pH. The bromide ion is the conjugate base of a strong acid, and so it is of negligible base strength (no appreciable base ionization). The solution is neutral.<\/p>\n<p id=\"fs-idm168102384\">(b) The Na<sup>+<\/sup> cation is inert and will not affect the pH of the solution; while the HCO<sub>3<\/sub><sup>\u2212<\/sup> anion is amphiprotic. The <em data-effect=\"italics\">K<\/em><sub>a<\/sub> of HCO<sub>3<\/sub><sup>\u2212<\/sup> is 4.7 \u00d7 10<sup>\u221211<\/sup>, and its <em data-effect=\"italics\">K<\/em><sub>b<\/sub> is <img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-1888\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f-300x51.png\" alt=\"\" width=\"176\" height=\"30\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f-300x51.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f-65x11.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f-225x38.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f-350x59.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4f.png 622w\" sizes=\"auto, (max-width: 176px) 100vw, 176px\" \/><\/p>\n<p id=\"fs-idm98756192\">Since <em data-effect=\"italics\">K<\/em><sub>b<\/sub> &gt;&gt; <em data-effect=\"italics\">K<\/em><sub>a<\/sub>, the solution is basic.<\/p>\n<p id=\"fs-idp9214400\">(c) The Na<sup>+<\/sup> cation is inert and will not affect the pH of the solution, while the HPO<sub>4<\/sub><sup>2<\/sup><sup>\u2212<\/sup> anion is amphiprotic. The <em data-effect=\"italics\">K<\/em><sub>a<\/sub> of HPO<sub>4<\/sub><sup>2<\/sup><sup>\u2212<\/sup> is 4.2 \u00d7 10<sup>\u221213<\/sup>,<\/p>\n<p id=\"fs-idp53880096\">and its <em data-effect=\"italics\">K<\/em><sub>b<\/sub> is <img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-1894\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k-300x47.png\" alt=\"\" width=\"160\" height=\"25\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k-300x47.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k-65x10.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k-225x35.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k-350x55.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4k.png 622w\" sizes=\"auto, (max-width: 160px) 100vw, 160px\" \/> Because <em data-effect=\"italics\">K<\/em><sub>b<\/sub> &gt;&gt; <em data-effect=\"italics\">K<\/em><sub>a<\/sub>, the solution is basic.<\/p>\n<p id=\"fs-idp10452272\">(d) The NH<sub>4<\/sub><sup>+<\/sup> ion is acidic (see above discussion) and the F<sup>\u2212<\/sup> ion is basic (conjugate base of the weak acid HF). Comparing the two ionization constants: <em data-effect=\"italics\">K<\/em><sub>a<\/sub> of NH<sub>4<\/sub><sup>+<\/sup> is 5.6 \u00d7 10<sup>\u221210<\/sup> and <em data-effect=\"italics\">K<\/em><sub>b<\/sub> of F<sup>\u2212<\/sup> is 1.4 \u00d7 10<sup>\u221211<\/sup>, so the solution is acidic, since <em data-effect=\"italics\">K<\/em><sub>a<\/sub> &gt; <em data-effect=\"italics\">K<\/em><sub>b<\/sub>.<\/p>\n<p id=\"fs-idm140849264\"><strong>Check Your Learning:<\/strong><\/p>\n<p>Determine whether aqueous solutions of the following salts are acidic, basic, or neutral:<\/p>\n<p id=\"fs-idm15098896\">(a) K<sub>2<\/sub>CO<sub>3<\/sub><\/p>\n<p id=\"fs-idm75225328\">(b) CaCl<sub>2<\/sub><\/p>\n<p id=\"fs-idm290933120\">(c) KH<sub>2<\/sub>PO<sub>4<\/sub><\/p>\n<p id=\"fs-idm223869584\">(d) (NH<sub>4<\/sub>)<sub>2<\/sub>CO<sub>3<\/sub><\/p>\n<p>&nbsp;<\/p>\n<div id=\"fs-idm42020240\" data-type=\"note\">\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\n<p id=\"fs-idm5299888\">(a) basic; (b) neutral; (c) acidic; (d) basic<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-idm108915120\" class=\"bc-section section\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>The Ionization of Hydrated Metal Ions<\/strong><\/h3>\n<p id=\"fs-idm252144288\">Unlike the group 1 and 2 metal ions of the preceding examples (Na<sup>+<\/sup>, Ca<sup>2+<\/sup>, etc.), some metal ions function as acids in aqueous solutions. These ions are not just loosely solvated by water molecules when dissolved, instead they are covalently bonded to a fixed number of water molecules to yield a complex ion. As an example, the dissolution of aluminum nitrate in water is typically represented as<\/p>\n<p>&nbsp;<\/p>\n<div id=\"fs-idm253215984\" style=\"padding-left: 40px\" data-type=\"equation\">Al(NO<sub>3<\/sub>)<sub>3<\/sub>(<em>s<\/em>) \u2192 Al<sup>3+<\/sup>(<em>aq<\/em>) + 3NO<sub>3<\/sub><sup>&#8211;<\/sup>(<em>aq<\/em>)<\/div>\n<p id=\"fs-idm252419632\">However, the aluminum(III) ion actually reacts with six water molecules to form a stable complex ion, and so the more explicit representation of the dissolution process is<\/p>\n<div id=\"fs-idm117678832\" style=\"padding-left: 40px\" data-type=\"equation\">Al(NO<sub>3<\/sub>)<sub>3<\/sub>(<em>s<\/em>)\u00a0 + 6H<sub>2<\/sub>O(l) \u2192 Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + 3NO<sub>3<\/sub><sup>&#8211;<\/sup>(<em>aq<\/em>)<\/div>\n<p id=\"fs-idm251913856\">As shown in <a class=\"autogenerated-content\" href=\"#CNX_Chem_14_04_hydronium\">(Figure)<\/a>, the Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup> ions involve bonds between a central Al atom and the O atoms of the six water molecules. Consequently, the bonded water molecules&#8217; O\u2013H bonds are more polar than in nonbonded water molecules, making the bonded molecules more prone to donation of a hydrogen ion:<\/p>\n<div id=\"fs-idm108244016\" style=\"padding-left: 40px\" data-type=\"equation\">Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Al(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 1.4 \u00d7 10<sup>-5<\/sup><\/div>\n<div id=\"fs-idm46178496\" data-type=\"equation\"><\/div>\n<div id=\"CNX_Chem_14_04_hydronium\" class=\"scaled-down\">\n<div class=\"bc-figcaption figcaption\">When an aluminum ion reacts with water, the hydrated aluminum ion becomes a weak acid.<\/div>\n<p><span id=\"fs-idp82299440\" data-type=\"media\" data-alt=\"A reaction is shown using ball and stick models. On the left, inside brackets with a superscript of 3 plus outside to the right is structure labeled \u201c[ A l ( H subscript 2 O ) subscript 6 ] superscript 3 plus.\u201d Inside the brackets is s central grey atom to which 6 red atoms are bonded in an arrangement that distributes them evenly about the central grey atom. Each red atom has two smaller white atoms attached in a forked or bent arrangement. Outside the brackets to the right is a space-filling model that includes a red central sphere with two smaller white spheres attached in a bent arrangement. Beneath this structure is the label \u201cH subscript 2 O.\u201d A double sided arrow follows. Another set of brackets follows to the right of the arrows which have a superscript of two plus outside to the right. The structure inside the brackets is similar to that on the left, except a white atom is removed from the structure. The label below is also changed to \u201c[ A l ( H subscript 2 O ) subscript 5 O H ] superscript 2 plus.\u201d To the right of this structure and outside the brackets is a space filling model with a central red sphere to which 3 smaller white spheres are attached. This structure is labeled \u201cH subscript 3 O superscript plus.\u201d\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_14_04_hydronium-1.jpg\" alt=\"A reaction is shown using ball and stick models. On the left, inside brackets with a superscript of 3 plus outside to the right is structure labeled \u201c[ A l ( H subscript 2 O ) subscript 6 ] superscript 3 plus.\u201d Inside the brackets is s central grey atom to which 6 red atoms are bonded in an arrangement that distributes them evenly about the central grey atom. Each red atom has two smaller white atoms attached in a forked or bent arrangement. Outside the brackets to the right is a space-filling model that includes a red central sphere with two smaller white spheres attached in a bent arrangement. Beneath this structure is the label \u201cH subscript 2 O.\u201d A double sided arrow follows. Another set of brackets follows to the right of the arrows which have a superscript of two plus outside to the right. The structure inside the brackets is similar to that on the left, except a white atom is removed from the structure. The label below is also changed to \u201c[ A l ( H subscript 2 O ) subscript 5 O H ] superscript 2 plus.\u201d To the right of this structure and outside the brackets is a space filling model with a central red sphere to which 3 smaller white spheres are attached. This structure is labeled \u201cH subscript 3 O superscript plus.\u201d\" data-media-type=\"image\/jpeg\" \/><\/span><\/p>\n<\/div>\n<p id=\"fs-idm167123728\">Aside from the alkali metals (group 1) and some alkaline earth metals (group 2), most other metal ions will undergo acid ionization to some extent when dissolved in water. The acid strength of these complex ions typically increases with increasing charge and decreasing size of the metal ions. The first-step acid ionization equations for a few other acidic metal ions are shown below:<\/p>\n<div id=\"fs-idp56836016\" style=\"padding-left: 40px\" data-type=\"equation\">Fe(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Fe(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 6 \u00d7 10<sup>-3<\/sup><\/div>\n<div id=\"fs-idm116986352\" style=\"padding-left: 40px\" data-type=\"equation\">Cu(H<sub>2<\/sub>O)<sub>6<\/sub><sup>2+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Cu(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 3 \u00d7 10<sup>-8<\/sup><\/div>\n<div id=\"fs-idm166964496\" data-type=\"equation\"><\/div>\n<div id=\"fs-idm171178400\" class=\"textbox textbox--examples\" data-type=\"example\">\n<p id=\"fs-idm122608832\"><strong>Hydrolysis of [Al(H<sub>2<\/sub>O)<sub>6<\/sub>]<sup>3+<\/sup> <\/strong><\/p>\n<p>Calculate the pH of a 0.10-<em data-effect=\"italics\">M<\/em> solution of aluminum chloride, which dissolves completely to give the hydrated aluminum ion, Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>, in solution.<\/p>\n<p id=\"fs-idp112354272\"><strong>Solution:<\/strong><\/p>\n<p>The equation for the reaction and <em data-effect=\"italics\">K<\/em><sub>a<\/sub> are:<span data-type=\"newline\"><br \/>\n<\/span><\/p>\n<div id=\"fs-idm224297104\" data-type=\"equation\">Al(H<sub>2<\/sub>O)<sub>6<\/sub><sup>3+<\/sup>(<em>aq<\/em>) + H<sub>2<\/sub>O(<em>l<\/em>) \u21cc H<sub>3<\/sub>O<sup>+<\/sup>(<em>aq<\/em>) + Al(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>(<em>aq<\/em>)\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0K<sub>a<\/sub> = 1.4 \u00d7 10<sup>-5<\/sup><\/div>\n<p><span data-type=\"newline\"><br \/>\n<\/span> An ICE table with the provided information is<span data-type=\"newline\"><br \/>\n<\/span><\/p>\n<p><span id=\"fs-idm136267808\" data-type=\"media\" data-alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium concentration ( M ). The second column has the header of \u201cA l ( H subscript 2 O ) subscript 6 superscript 3 positive sign plus H subscript 2 O equilibrium arrow H subscript 3 O superscript positive sign plus A l ( H subscript 2 O ) subscript 5 ( O H ) superscript 2 positive sign.\u201d Under the second column is a subgroup of three columns and three rows. The first column has the following: 0.10, negative x, 0.10 minus x. The second column has the following: approximately 0, positive x, x. The third column has the following: 0, positive x, x.\"><img decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/CNX_Chem_14_04_ICETable13_img-1.jpg\" alt=\"This table has two main columns and four rows. The first row for the first column does not have a heading and then has the following in the first column: Initial concentration ( M ), Change ( M ), Equilibrium concentration ( M ). The second column has the header of \u201cA l ( H subscript 2 O ) subscript 6 superscript 3 positive sign plus H subscript 2 O equilibrium arrow H subscript 3 O superscript positive sign plus A l ( H subscript 2 O ) subscript 5 ( O H ) superscript 2 positive sign.\u201d Under the second column is a subgroup of three columns and three rows. The first column has the following: 0.10, negative x, 0.10 minus x. The second column has the following: approximately 0, positive x, x. The third column has the following: 0, positive x, x.\" data-media-type=\"image\/jpeg\" \/><\/span><\/p>\n<p><span data-type=\"newline\"><br \/>\n<\/span> Substituting the expressions for the equilibrium concentrations into the equation for the ionization constant yields:<span data-type=\"newline\"><br \/>\n<\/span><\/p>\n<div id=\"fs-idm98439712\" style=\"padding-left: 40px\" data-type=\"equation\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-1897\" src=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-300x188.png\" alt=\"\" width=\"211\" height=\"132\" srcset=\"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-300x188.png 300w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-768x480.png 768w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-65x41.png 65w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-225x141.png 225w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l-350x219.png 350w, https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-content\/uploads\/sites\/1463\/2021\/07\/14.4l.png 828w\" sizes=\"auto, (max-width: 211px) 100vw, 211px\" \/><\/div>\n<p><span data-type=\"newline\"><br \/>\n<\/span> Assuming <em data-effect=\"italics\">x<\/em> &lt; 0.05 \u00d7 0.10 M, i.e. <em data-effect=\"italics\">x<\/em> &lt; 0.0050 M and solving the simplified equation gives:<span data-type=\"newline\"><br \/>\n<\/span><\/p>\n<div id=\"fs-idp4666608\" style=\"padding-left: 40px\" data-type=\"equation\"><em>x<\/em> = 1.2 \u00d7 10<sup>-3<\/sup> M\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 ASSUMPTION VALID<\/div>\n<p><span data-type=\"newline\"><br \/>\n<\/span> The ICE table defined <em data-effect=\"italics\">x<\/em> as equal to the hydronium ion concentration, and so the pH is calculated to be<span data-type=\"newline\"><br \/>\n<\/span><\/p>\n<div id=\"fs-idm156052944\" style=\"padding-left: 40px\" data-type=\"equation\">[H<sub>3<\/sub>O<sup>+<\/sup>] = <em>x<\/em> = 1.2 \u00d7 10<sup>-3<\/sup> M<\/div>\n<p><span data-type=\"newline\">\u00a0<\/span><\/p>\n<div id=\"fs-idm161964736\" style=\"padding-left: 40px\" data-type=\"equation\">pH = \u2212log[H<sub>3<\/sub>O<sup>+<\/sup>] = 2.92\u00a0 \u00a0 \u00a0(an acidic solution)<\/div>\n<div data-type=\"equation\"><\/div>\n<p id=\"fs-idm175924752\"><strong>Check Your Learning:<\/strong><\/p>\n<p>What is [Al(H<sub>2<\/sub>O)<sub>5<\/sub>(OH)<sup>2+<\/sup>] in a 0.15-<em data-effect=\"italics\">M<\/em> solution of Al(NO<sub>3<\/sub>)<sub>3<\/sub> that contains enough of the strong acid HNO<sub>3<\/sub> to bring [H<sub>3<\/sub>O<sup>+<\/sup>] to 0.10 <em data-effect=\"italics\">M<\/em>?<\/p>\n<p>&nbsp;<\/p>\n<div id=\"fs-idm38454832\" data-type=\"note\">\n<div data-type=\"title\"><strong>Answer:<\/strong><\/div>\n<p id=\"fs-idp86512272\">2.1 \u00d7 10<sup>\u22125<\/sup><em data-effect=\"italics\">M<\/em><\/p>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"fs-idm180137840\" class=\"summary\" data-depth=\"1\">\n<h3 data-type=\"title\"><strong>Key Concepts and Summary<\/strong><\/h3>\n<p id=\"fs-idp3314288\">The ions composing salts may possess acidic or basic character, ionizing when dissolved in water to yield acidic or basic solutions. Acidic cations are typically the conjugate partners of weak bases, and basic anions are the conjugate partners of weak acids. Many metal ions bond to water molecules when dissolved to yield complex ions that may function as acids.<\/p>\n<\/div>\n<div id=\"fs-idm46050816\" class=\"exercises\" data-depth=\"1\">\n<div id=\"fs-idm1823584\" data-type=\"exercise\">\n<div id=\"fs-idm138043888\" data-type=\"problem\">\n<p id=\"fs-idp30279488\">\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"author":1392,"menu_order":5,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-797","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":766,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/797","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/users\/1392"}],"version-history":[{"count":10,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/797\/revisions"}],"predecessor-version":[{"id":2173,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/797\/revisions\/2173"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/parts\/766"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapters\/797\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/media?parent=797"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/pressbooks\/v2\/chapter-type?post=797"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/contributor?post=797"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/aperrott\/wp-json\/wp\/v2\/license?post=797"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}