{"id":3445,"date":"2015-05-06T03:51:00","date_gmt":"2015-05-06T03:51:00","guid":{"rendered":"https:\/\/courses.candelalearning.com\/oschemtemp\/?post_type=chapter&#038;p=3445"},"modified":"2020-12-31T17:12:48","modified_gmt":"2020-12-31T17:12:48","slug":"bronsted-lowry-acids-and-bases-2","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/chapter\/bronsted-lowry-acids-and-bases-2\/","title":{"raw":"Br\u00f8nsted-Lowry Acids and Bases","rendered":"Br\u00f8nsted-Lowry Acids and Bases"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Identify acids, bases, and conjugate acid-base pairs according to the Br\u00f8nsted-Lowry definition<\/li>\r\n \t<li>Write equations for acid and base ionization reactions<\/li>\r\n \t<li>Use the ion-product constant for water to calculate hydronium and hydroxide ion concentrations<\/li>\r\n \t<li>Describe the acid-base behavior of amphiprotic substances<\/li>\r\n<\/ul>\r\n<\/div>\r\n<p id=\"fs-idm196456848\">The acid-base reaction class has been studied for quite some time. In 1680, Robert\u00a0<span id=\"term570\" class=\"no-emphasis\">Boyle<\/span>\u00a0reported traits of acid solutions that included their ability to dissolve many substances, to change the colors of certain natural dyes, and to lose these traits after coming in contact with alkali (base) solutions. In the eighteenth century, it was recognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be CO<sub>2<\/sub>), and interact with alkalis to form neutral substances. In 1815, Humphry\u00a0<span id=\"term571\" class=\"no-emphasis\">Davy<\/span>\u00a0contributed greatly to the development of the modern acid-base concept by demonstrating that hydrogen is the essential constituent of acids. Around that same time, Joseph Louis Gay-Lussac concluded that acids are substances that can neutralize bases and that these two classes of substances can be defined only in terms of each other. The significance of hydrogen was reemphasized in 1884 when Svante\u00a0<span id=\"term572\" class=\"no-emphasis\">Arrhenius<\/span>\u00a0defined an acid as a compound that dissolves in water to yield hydrogen cations (now recognized to be hydronium ions) and a base as a compound that dissolves in water to yield hydroxide anions.<\/p>\r\n<p id=\"fs-idm26037424\">Johannes Br\u00f8nsted and Thomas Lowry proposed a more general description in 1923 in which acids and bases were defined in terms of the transfer of hydrogen ions, H<sup>+<\/sup>. (Note that these hydrogen ions are often referred to simply as\u00a0<em>protons<\/em>, since that subatomic particle is the only component of cations derived from the most abundant hydrogen isotope,\u00a0<sup>1<\/sup>H.) A compound that donates a proton to another compound is called a\u00a0<strong>Br\u00f8nsted-Lowry acid<\/strong>, and a compound that accepts a proton is called a\u00a0<strong>Br\u00f8nsted-Lowry base<\/strong>. An acid-base reaction is, thus, the transfer of a proton from a donor (acid) to an acceptor (base).<\/p>\r\n<p id=\"fs-idm56373376\">The concept of\u00a0<em>conjugate pairs<\/em>\u00a0is useful in describing Br\u00f8nsted-Lowry acid-base reactions (and other reversible reactions, as well). When an acid donates H<sup>+<\/sup>, the species that remains is called the\u00a0<strong>conjugate base<\/strong>\u00a0of the acid because it reacts as a proton acceptor in the reverse reaction. Likewise, when a base accepts H<sup>+<\/sup>, it is converted to its\u00a0<strong>conjugate acid<\/strong>. The reaction between water and ammonia illustrates this idea. In the forward direction, water acts as an acid by donating a proton to ammonia and subsequently becoming a hydroxide ion, OH<sup>\u2212<\/sup>, the conjugate base of water. The ammonia acts as a base in accepting this proton, becoming an ammonium ion,\u00a0<span class=\"os-math-in-para\"><span id=\"MathJax-Element-92-Frame\" class=\"MathJax\" style=\"overflow: initial; font-style: normal; font-weight: normal; line-height: normal; font-size: 14px; text-indent: 0px; text-align: left; letter-spacing: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px;\" role=\"presentation\"><span id=\"MathJax-Span-3014\" class=\"math\"><span id=\"MathJax-Span-3015\" class=\"mrow\"><span id=\"MathJax-Span-3016\" class=\"semantics\"><span id=\"MathJax-Span-3017\" class=\"mrow\"><span id=\"MathJax-Span-3018\" class=\"mrow\"><span id=\"MathJax-Span-3019\" class=\"msup\"><span id=\"MathJax-Span-3020\" class=\"mrow\"><span id=\"MathJax-Span-3021\" class=\"msub\"><span id=\"MathJax-Span-3022\" class=\"mrow\"><span id=\"MathJax-Span-3023\" class=\"mtext\">NH<\/span><\/span><span id=\"MathJax-Span-3024\" class=\"mrow\"><span id=\"MathJax-Span-3025\" class=\"mn\">4<\/span><\/span><\/span><\/span><span id=\"MathJax-Span-3026\" class=\"mrow\"><span id=\"MathJax-Span-3027\" class=\"mtext\">+<\/span><\/span><\/span><span id=\"MathJax-Span-3028\" class=\"mtext\">,<\/span><\/span><\/span><\/span><\/span><\/span><span class=\"MJX_Assistive_MathML\" role=\"presentation\">NH4+,<\/span><\/span><\/span>\u00a0the conjugate acid of ammonia. In the reverse direction, a hydroxide ion acts as a base in accepting a proton from ammonium ion, which acts as an acid.<\/p>\r\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/05\/23213723\/CNX_Chem_14_01_conjugate_img.jpg\" alt=\"This figure has three parts in two rows. In the first row, two diagrams of acid-base pairs are shown. On the left, a space filling model of H subscript 2 O is shown with a red O atom at the center and two smaller white H atoms attached in a bent shape. Above this model is the label \u201cH subscript 2 O (acid)\u201d in purple. An arrow points right, which is labeled \u201cRemove H superscript plus.\u201d To the right is another space filling model with a single red O atom to which a single smaller white H atom is attached. The label in purple above this model reads, \u201cO H superscript negative (conjugate base).\u201d Above both of these red and white models is an upward pointing bracket that is labeled \u201cConjugate acid-base pair.\u201d To the right is a space filling model with a central blue N atom to which three smaller white H atoms are attached in a triangular pyramid arrangement. A label in green above reads \u201cN H subscript 3 (base).\u201d An arrow labeled \u201cAdd H superscript plus\u201d points right. To the right of the arrow is another space filling model with a blue central N atom and four smaller white H atoms in a tetrahedral arrangement. The green label above reads \u201cN H subscript 3 superscript plus (conjugate acid).\u201d Above both of these blue and white models is an upward pointing bracket that is labeled \u201cConjugate acid-base pair.\u201d The second row of the figure shows the chemical reaction, H subscript 2 O ( l ) is shown in purple, and is labeled below in purple as \u201cacid,\u201d plus N H subscript 3 (a q) in green, labeled below in green as \u201cbase,\u201d followed by a double sided arrow arrow and O H superscript negative (a q) in purple, labeled in purple as \u201cconjugate base,\u201d plus N H subscript 4 superscript plus (a q)\u201d in green, which is labeled in green as \u201cconjugate acid.\u201d The acid on the left side of the equation is connected to the conjugate base on the right with a purple line. Similarly, the base on the left is connected to the conjugate acid on the right side.\" \/>\r\n\r\nThe reaction between a Br\u00f8nsted-Lowry acid and water is called <strong>acid ionization<\/strong>. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions:\r\n\r\n<img class=\"aligncenter\" src=\"https:\/\/openstax.org\/resources\/1f9a8c21ac9da03aa5517b79f0d772d3f8fbb920\" alt=\"This figure has two rows. In both rows, a chemical reaction is shown. In the first, structural formulas are provided. In this model, in red, is an O atom which has H atoms singly bonded above and to the right. The O atom has lone pairs of electron dots on its left and lower sides. This is followed by a plus sign. The plus sign is followed, in blue, by an N atom with one lone pair of electron dots. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. An equilibrium arrow follows this structure. To the right, in brackets is a structure where an N atom bonded to an H atom, which is red, appears. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. Outside the brackets, to the right, is a superscript positive sign. This structure is followed by a plus sign. Another structure that appears in brackets also appears. An O atom with three lone pairs of electron dots is bonded to an H atom. There is a superscript negative sign outside the brackets. Under the initial equation, is this equation: H subscript 2 plus C subscript 5 N H subscript 5 equilibrium arrow C subscript 5 N H subscript 6 superscript positive sign plus O H superscript negative sign. H subscript 2 O is labeled, \u201cacid,\u201d in red. C subscript 5 N H subscript 5 is labeled, \u201cbase,\u201d in blue. C subscript 5 N H subscript 6 superscript positive sign is labeled, \u201cacid\u201d in blue. O H superscript negative sign is labeled, \u201cbase,\u201d in red.\" width=\"726\" height=\"233\" \/>\r\n\r\n<strong><span id=\"term576\">Base ionization<\/span><\/strong>\u00a0of a species occurs when it accepts protons from water molecules. In the example below, pyridine molecules, C<sub>5<\/sub>NH<sub>5<\/sub>, undergo base ionization when dissolved in water, yielding hydroxide and pyridinium ions:\r\n\r\n<img class=\"aligncenter\" src=\"https:\/\/openstax.org\/resources\/b523238d04bf275f461c36ececbc297f34fe7181\" alt=\"This figure has two rows. In both rows, a chemical reaction is shown. In the first, structural formulas are provided. In this model, in red, is an O atom which has H atoms singly bonded above and to the right. The O atom has lone pairs of electron dots on its left and lower sides. This is followed by a plus sign. The plus sign is followed, in blue, by an N atom with one lone pair of electron dots. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. An equilibrium arrow follows this structure. To the right, in brackets is a structure where an N atom bonded to an H atom, which is red, appears. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. Outside the brackets, to the right, is a superscript positive sign. This structure is followed by a plus sign. Another structure that appears in brackets also appears. An O atom with three lone pairs of electron dots is bonded to an H atom. There is a superscript negative sign outside the brackets. To the right, is the equation: k equals [ C subscript 5 N H subscript 6 superscript positive sign ] [ O H superscript negative sign] all divided by [ C subscript 5 N H subscript 5 ]. Under the initial equation, is this equation: H subscript 2 plus C subscript 5 N H subscript 5 equilibrium arrow C subscript 5 N H subscript 6 superscript positive sign plus O H superscript negative sign. H subscript 2 O is labeled, \u201cacid,\u201d in red. C subscript 5 N H subscript 5 is labeled, \u201cbase,\u201d in blue. C subscript 5 N H subscript 6 superscript positive sign is labeled, \u201cacid\u201d in blue. O H superscript negative sign is labeled, \u201cbase,\u201d in red.\" width=\"727\" height=\"251\" \/>\r\n\r\nThe preceding ionization reactions suggest that water may function as both a base (as in its reaction with hydrogen fluoride) and an acid (as in its reaction with ammonia). Species capable of either donating or accepting protons are called\u00a0<strong><span id=\"term577\">amphiprotric<\/span><\/strong>, or more generally,\u00a0<strong><span id=\"term578\">amphoteric<\/span><\/strong>, a term that may be used for acids and bases per definitions other than the Br\u00f8nsted-Lowry one. The equations below show the two possible acid-base reactions for two amphiprotic species, bicarbonate ion and water:\r\n<p class=\"p1\" style=\"text-align: center;\">[latex]{\\text{HCO}_{3}}^{-}(\\text{aq})+\\text{H}_{2}\\text{O}(\\text{l})\\qquad{\\text{CO}_{3}}^{2-}(\\text{aq})+\\text{H}_{3}\\text{O}^{+}(\\text{aq})[\/latex]<span id=\"MathJax-Element-93-Frame\" class=\"MathJax\" style=\"overflow: initial; font-style: normal; font-weight: normal; line-height: normal; font-size: 14px; text-indent: 0px; text-align: center; letter-spacing: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px;\" role=\"presentation\"><\/span><\/p>\r\n<p style=\"text-align: center;\">[latex]{\\text{HCO}_{3}}^{-}(\\text{aq})+\\text{H}_{2}\\text{O}(\\text{l})\\qquad\\text{H}_{2}\\text{CO}\r\n_{3}(\\text{aq})+\\text{OH}^{-}(\\text{aq})[\/latex]<\/p>\r\nThe first equation represents the reaction of bicarbonate as an acid with water as a base, whereas the second represents reaction of bicarbonate as a base with water as an acid. When bicarbonate is added to water, both these equilibria are established simultaneously and the composition of the resulting solution may be determined through appropriate equilibrium calculations, as described later in this chapter.\r\n<p id=\"fs-idm206801664\">In the liquid state, molecules of an amphiprotic substance can react with one another as illustrated for water in the equations below:<\/p>\r\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/05\/23213728\/CNX_Chem_14_01_Water_img.jpg\" alt=\"This figure has two rows. In both rows, a chemical reaction is shown. In the first, structural formulas are provided. In this model, in purple, O atom which has H atoms singly bonded above and to the right. The O atom has pairs of electron dots on its left and lower sides. This is followed by a plus sign, which is followed in green by an O atom which has H atoms singly bonded above and to the right. The O atom has pairs of electron dots on its left and lower sides. A double arrow follows. To the right, in brackets is a structure with a central O atom in green, with green H atoms singly bonded above and to the right. A pair of green electron dots is on the lower side of the O atom. To the left of the green O atom, a purple H atom is singly bonded. Outside the brackets to the right is a superscript plus. This is followed by a plus sign and an O atom in purple with pairs of electron dots above, left, and below. An H atom is singly bonded to the right. This atom has a superscript negative sign. The reaction is written in symbolic form below. H subscript 2 O is labeled in purple below as \u201cAcid subscript 1.\u201d This is followed by plus H subscript 2 O, which is labeled in green below as \u201cBase subscript 2.\u201d A double sided arrow follows. To the right is H subscript 3 O superscript plus, which is labeled in green as below in as \u201cAcid subscript 2.\u201d This is followed by plus and O with pairs of dots above, below, and to the left with a singly bonded H on the right with a superscript negative. The label below in purple reads, \u201c Base subscript 1.\u201d\" \/>\r\n\r\nThe process in which like molecules react to yield ions is called\u00a0<strong><span id=\"term579\">autoionization<\/span><\/strong>. Liquid water undergoes autoionization to a very slight extent; at 25 \u00b0C, approximately two out of every billion water molecules are ionized. The extent of the water autoionization process is reflected in the value of its equilibrium constant, the\u00a0<strong><span id=\"term580\">ion-product constant for water,\u00a0<em>K<\/em><sub>w<\/sub><\/span><\/strong>:\r\n<p style=\"text-align: center;\">[latex]{\\text{H}}_{2}\\text{O}\\left(l\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\qquad{K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right][\/latex]<\/p>\r\nThe slight ionization of pure water is reflected in the small value of the equilibrium constant; at 25 \u00b0C, <em>K<\/em><sub>w<\/sub> has a value of 1.0 [latex]\\times [\/latex] 10<sup>\u221214<\/sup>. The process is endothermic, and so the extent of ionization and the resulting concentrations of hydronium ion and hydroxide ion increase with temperature. For example, at 100 \u00b0C, the value for <em>K<\/em><sub>w<\/sub> is about 5.1 [latex]\\times [\/latex] 10<sup>\u221213<\/sup>, roughly 100-times larger than the value at 25 \u00b0C.\r\n<div class=\"textbox examples\">\r\n<h3>Example 1:\u00a0Ion Concentrations in Pure Water<\/h3>\r\nWhat are the hydronium ion concentration and the hydroxide ion concentration in pure water at 25 \u00b0C?\r\n[reveal-answer q=\"160586\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"160586\"]\r\n\r\nThe autoionization of water yields the same number of hydronium and hydroxide ions. Therefore, in pure water, [latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=\\left[\\text{OH}^{-}\\right][\/latex]. At 25 \u00b0C: [latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]={\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]}^{\\text{2+}}={\\left[{\\text{OH}}^{-}\\right]}^{\\text{2+}}=1.0\\times {10}^{-14}[\/latex]\r\n\r\nSo:\r\n<p style=\"text-align: center;\">[latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=\\left[{\\text{OH}}^{-}\\right]=\\sqrt{1.0\\times {10}^{-14}}=1.0\\times {10}^{-7}M[\/latex]<\/p>\r\nThe hydronium ion concentration and the hydroxide ion concentration are the same, and we find that both equal 1.0\u00a0\u00d7\u00a010<sup>\u22127<\/sup><em>M<\/em>.\r\n\r\n[\/hidden-answer]\r\n<h4>Check Your Learning<\/h4>\r\nThe ion product of water at 80 \u00b0C is 2.4\u00a0\u00d7\u00a010<sup>\u221213<\/sup>. What are the concentrations of hydronium and hydroxide ions in pure water at 80 \u00b0C?\r\n\r\n[reveal-answer q=\"709034\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"709034\"][latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=\\left[\\text{OH}^{-}\\right]=4.9\\times 10^{-7}M[\/latex][\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox examples\">\r\n<h3>Example 2:\u00a0The Inverse Proportionality of [H<sub>3<\/sub>O<sup>+<\/sup>] and [OH<sup>\u2212<\/sup>]<\/h3>\r\nA solution of carbon dioxide in water has a hydronium ion concentration of 2.0 [latex]\\times [\/latex] 10<sup>\u22126<\/sup><em>M<\/em>. What is the concentration of hydroxide ion at 25 \u00b0C?\r\n\r\n[reveal-answer q=\"647487\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"647487\"]\r\n\r\nWe know the value of the ion-product constant for water at 25 \u00b0C:\r\n<p style=\"text-align: center;\">[latex]2{\\text{H}}_{2}\\text{O}\\left(l\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right){K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=1.0\\times {10}^{-14}[\/latex]<\/p>\r\nThus, we can calculate the missing equilibrium concentration.\r\n\r\nRearrangement of the <em>K<\/em><sub>w<\/sub> expression yields that [OH<sup>\u2212<\/sup>] is directly proportional to the inverse of [latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right][\/latex]:\r\n<p style=\"text-align: center;\">[latex]\\left[{\\text{OH}}^{-}\\right]=\\dfrac{{K}_{\\text{w}}}{\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]}=\\dfrac{1.0\\times {10}^{-14}}{2.0\\times {10}^{-6}}=5.0\\times {10}^{-9}[\/latex]<\/p>\r\nThe hydroxide ion concentration in water is reduced to 5.0 [latex]\\times [\/latex] 10<sup>\u22129<\/sup><em>M<\/em> as the hydrogen ion concentration increases to 2.0 [latex]\\times [\/latex] 10<sup>\u22126<\/sup><em>M<\/em>. This is expected from Le Ch\u00e2telier\u2019s principle; the autoionization reaction shifts to the left to reduce the stress of the increased hydronium ion concentration and the [OH<sup>\u2212<\/sup>] is reduced relative to that in pure water.\r\n\r\nA check of these concentrations confirms that our arithmetic is correct:\r\n<p style=\"text-align: center;\">[latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=\\left(2.0\\times {10}^{-6}\\right)\\left(5.0\\times {10}^{-9}\\right)=1.0\\times {10}^{-14}[\/latex]<\/p>\r\n[\/hidden-answer]\r\n<h4>Check Your Learning<\/h4>\r\nWhat is the hydronium ion concentration in an aqueous solution with a hydroxide ion concentration of 0.001 <em>M<\/em> at 25 \u00b0C?\r\n[reveal-answer q=\"366443\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"366443\"][latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=1\\times 10^{-11}M[\/latex][\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox examples\">\r\n<h3>Example 3:\u00a0Representing the Acid-Base Behavior of an Amphoteric Substance<\/h3>\r\nWrite separate equations representing the reaction of [latex]{\\text{HSO}}_{3}^{-}[\/latex]\r\n<ol>\r\n \t<li>as an acid with OH<sup>\u2212<\/sup><\/li>\r\n \t<li>as a base with HI<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"236960\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"236960\"]\r\n<ol>\r\n \t<li>[latex]{\\text{HSO}}_{3}^{-}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\rightleftharpoons {\\text{SO}}_{3}^{2-}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HSO}}_{3}^{-}\\left(aq\\right)+\\text{HI}\\left(aq\\right)\\rightleftharpoons {\\text{H}}_{2}{\\text{SO}}_{3}\\left(aq\\right)+{\\text{I}}^{-}\\left(aq\\right)[\/latex]<\/li>\r\n<\/ol>\r\n[\/hidden-answer]\r\n<h4>Check Your Learning<\/h4>\r\nWrite separate equations representing the reaction of [latex]{\\text{H}}_{2}{\\text{PO}}_{4}^{-}[\/latex]\r\n<ol>\r\n \t<li>as a base with HBr<\/li>\r\n \t<li>as an acid with OH<sup>\u2212<\/sup><\/li>\r\n<\/ol>\r\n[reveal-answer q=\"161818\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"161818\"]\r\n<ol>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}\\left(aq\\right)+\\text{HBr}\\left(aq\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{PO}}_{4}\\left(aq\\right)+{\\text{Br}}^{-}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\rightleftharpoons {\\text{HPO}}_{4}{}^{\\text{2-}}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\r\n<\/ol>\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key Concepts and Summary<\/h3>\r\nA compound that can donate a proton (a hydrogen ion) to another compound is called a Br\u00f8nsted-Lowry acid. The compound that accepts the proton is called a Br\u00f8nsted-Lowry base. The species remaining after a Br\u00f8nsted-Lowry acid has lost a proton is the conjugate base of the acid. The species formed when a Br\u00f8nsted-Lowry base gains a proton is the conjugate acid of the base. Thus, an acid-base reaction occurs when a proton is transferred from an acid to a base, with formation of the conjugate base of the reactant acid and formation of the conjugate acid of the reactant base. Amphiprotic species can act as both proton donors and proton acceptors. Water is the most important amphiprotic species. It can form both the hydronium ion, [latex]{\\text{H}}_{3}{\\text{O}}^{\\text{+}}[\/latex], and the hydroxide ion, OH<sup>\u2212<\/sup> when it undergoes autoionization:\r\n<p style=\"text-align: center;\">[latex]{\\text{2H}}_{2}\\text{O}\\left(l\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{+}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)[\/latex]<\/p>\r\nThe ion product of water, <em>K<\/em><sub>w<\/sub> is the equilibrium constant for the autoionization reaction:\r\n<p style=\"text-align: center;\">[latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{2}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=1.0\\times 1{0}^{-14}\\text{ at }25^{\\circ}\\text{C}[\/latex]<\/p>\r\n\r\n<h4>Key Equations<\/h4>\r\n<ul>\r\n \t<li>[latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{2}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=1.0\\times 1{0}^{-14}\\text{ at }25^{\\circ}\\text{C}[\/latex]<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Try It<\/h3>\r\n<ol>\r\n \t<li>Write equations that show NH<sub>3<\/sub> as both a conjugate acid and a conjugate base.<\/li>\r\n \t<li>Write equations that show [latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex] acting both as an acid and as a base.<\/li>\r\n \t<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry acid:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]{\\text{H}}_{3}{\\text{O}}^{\\text{+}}[\/latex]<\/li>\r\n \t<li>HCl<\/li>\r\n \t<li>NH<sub>3<\/sub><\/li>\r\n \t<li>CH<sub>3<\/sub>CO<sub>2<\/sub>H<\/li>\r\n \t<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry acid:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>HNO<sub>3<\/sub><\/li>\r\n \t<li>[latex]{\\text{PH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\r\n \t<li>H<sub>2<\/sub>S<\/li>\r\n \t<li>CH<sub>3<\/sub>CH<sub>2<\/sub>COOH<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>HS<sup>\u2212<\/sup><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry base:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>H<sub>2<\/sub>O<\/li>\r\n \t<li>OH<sup>\u2212<\/sup><\/li>\r\n \t<li>NH<sub>3<\/sub><\/li>\r\n \t<li>CN<sup>\u2212<\/sup><\/li>\r\n \t<li>S<sup>2\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry base:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>HS<sup>\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{PO}}_{4}{}^{\\text{3-}}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{NH}}_{2}{}^{-}[\/latex]<\/li>\r\n \t<li>C<sub>2<\/sub>H<sub>5<\/sub>OH<\/li>\r\n \t<li>O<sup>2\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What is the conjugate acid of each of the following? What is the conjugate base of each?\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>OH<sup>\u2212<\/sup><\/li>\r\n \t<li>H<sub>2<\/sub>O<\/li>\r\n \t<li>[latex]{\\text{HCO}}_{3}{}^{-}[\/latex]<\/li>\r\n \t<li>NH<sub>3<\/sub><\/li>\r\n \t<li>[latex]{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>H<sub>2<\/sub>O<sub>2<\/sub><\/li>\r\n \t<li>HS<sup>\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{H}}_{5}{\\text{N}}_{2}{}^{\\text{+}}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What is the conjugate acid of each of the following? What is the conjugate base of each?\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>H<sub>2<\/sub>S<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>PH<sub>3<\/sub><\/li>\r\n \t<li>HS<sup>\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{HSO}}_{3}{}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{3}{\\text{O}}_{2}{}^{\\text{+}}[\/latex]<\/li>\r\n \t<li>H<sub>4<\/sub>N<sub>2<\/sub><\/li>\r\n \t<li>CH<sub>3<\/sub>OH<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Identify and label the Br\u00f8nsted-Lowry acid, its conjugate base, the Br\u00f8nsted-Lowry base, and its conjugate acid in each of the following equations:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]{\\text{HNO}}_{3}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{H}}_{3}{\\text{O}}^{\\text{+}}+{\\text{NO}}_{3}{}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{CN}}^{-}+{\\text{H}}_{2}\\text{O}\\longrightarrow \\text{HCN}+{\\text{OH}}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{SO}}_{4}+{\\text{Cl}}^{-}\\longrightarrow \\text{HCl}+{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HSO}}_{4}{}^{-}+{\\text{OH}}^{-}\\longrightarrow {\\text{SO}}_{4}{}^{\\text{2-}}+{\\text{H}}_{2}\\text{O}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{O}}^{2-}+{\\text{H}}_{2}\\text{O}\\longrightarrow 2{\\mathrm{OH}}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\left[\\text{Cu}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{3}\\left(\\text{OH}\\right)\\right]}^{\\text{+}}+{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{6}\\right]}^{3+}\\longrightarrow {\\left[\\text{Cu}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{4}\\right]}^{2+}+{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{5}\\left(\\text{OH}\\right)\\right]}^{2+}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}\\text{S}+{\\text{NH}}_{2}{}^{-}\\longrightarrow {\\text{HS}}^{-}+{\\text{NH}}_{3}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Identify and label the Br\u00f8nsted-Lowry acid, its conjugate base, the Br\u00f8nsted-Lowry base, and its conjugate acid in each of the following equations:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]{\\text{NO}}_{2}{}^{-}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{HNO}}_{2}+{\\text{OH}}^{-}[\/latex]<\/li>\r\n \t<li>[latex]\\text{HBr}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{H}}_{3}{\\text{O}}^{\\text{+}}+{\\text{Br}}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HS}}^{-}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{H}}_{2}\\text{S}+{\\text{OH}}^{-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}+{\\text{OH}}^{-}\\longrightarrow {\\text{HPO}}_{4}{}^{\\text{2-}}+{\\text{H}}_{2}\\text{O}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}+\\text{HCl}\\longrightarrow {\\text{H}}_{3}{\\text{PO}}_{4}+{\\text{Cl}}^{-}[\/latex]<\/li>\r\n \t<li>[latex]\\left[\\text{Fe}\\left(\\text{H}_{2}\\text{O}\\right)_{5}\\left(\\text{OH}\\right)\\right]^{2+}+\\left[\\text{Al}\\left(\\text{H}_{2}\\text{O}\\right)_6\\right]^{3+}\\longrightarrow\\left[\\text{Fe}\\left(\\text{H}_{2}\\text{O}\\right)_{6}\\right]^{3+}+\\left[\\text{Al}\\left(\\text{H}_2\\text{O}\\right)_5\\left(\\text{OH}\\right)\\right]^{2+}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{CH}}_{3}\\text{OH}+{\\text{H}}^{-}\\longrightarrow {\\text{CH}}_{3}{\\text{O}}^{-}+{\\text{H}}_{2}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What are amphiprotic species? Illustrate with suitable equations.<\/li>\r\n \t<li>State which of the following species are amphiprotic and write chemical equations illustrating the amphiprotic character of these species:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>H<sub>2<\/sub>O<\/li>\r\n \t<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>S<sup>2\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{CO}}_{3}{}^{\\text{2-}}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>State which of the following species are amphiprotic and write chemical equations illustrating the amphiprotic character of these species.\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>NH<sub>3<\/sub><\/li>\r\n \t<li>[latex]{\\text{HPO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>Br<sup>\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{ASO}}_{4}{}^{\\text{3-}}[\/latex]<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Is the self ionization of water endothermic or exothermic? The ionization constant for water (<em>K<\/em><sub>w<\/sub>) is 2.9 [latex]\\times [\/latex] 10<sup>\u221214<\/sup> at 40 \u00b0C and 9.6 [latex]\\times [\/latex] 10<sup>\u221214<\/sup> at 60 \u00b0C.<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"41360\"]Show Selected Solutions[\/reveal-answer]\r\n[hidden-answer a=\"41360\"]\r\n\r\n1.\u00a0One example for NH<sub>3<\/sub> as a conjugate acid: [latex]{\\text{NH}}_{2}{}^{-}+{\\text{H}}^{\\text{+}}\\longrightarrow {\\text{NH}}_{3}[\/latex]; as a conjugate base: [latex]{\\text{NH}}_{4}{}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\longrightarrow {\\text{NH}}_{3}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]\r\n\r\n3. The net ionic equations are as follows:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]{\\text{H}}_{3}{\\text{O}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\r\n \t<li>[latex]\\text{HCl}\\left(l\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{Cl}}^{-}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{NH}}_{3}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{NH}}_{2}^{-}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{CH}}_{3}{\\text{CO}}_{2}\\text{H}\\left(aq\\right)\\longrightarrow {\\text{H}}^{\\text{+}}\\left(aq\\right)+{\\text{CH}}_{3}{\\text{CO}}_{2}^{-}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{NH}}_{3}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HSO}}_{4}{}^{-}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{SO}}_{4}^{2-}\\left(aq\\right)[\/latex]<\/li>\r\n<\/ol>\r\n5. The net ionic equations are as follows:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]{\\text{H}}_{2}\\text{O}\\left(l\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}_{3}{\\text{O}}^{+}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{OH}}^{-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{NH}}_{3}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{NH}}_{4}^{+}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{CN}}^{-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow\\text{HCN}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>(e) [latex]{\\text{S}}^{2-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{HS}}^{-}\\left(aq\\right)[\/latex]<\/li>\r\n \t<li>(f) [latex]{\\text{H}}_{2}{\\text{PO}}_{4}^{-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}_{3}{\\text{PO}}_{4}\\left(aq\\right)[\/latex]<\/li>\r\n<\/ol>\r\n7.\u00a0The conjugate acids and bases are as follows:\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>H<sub>2<\/sub>O, O<sup>2\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{H}}_{3}{\\text{O}}^{+}[\/latex], OH<sup>\u2212<\/sup><\/li>\r\n \t<li>H<sub>2<\/sub>CO<sub>3<\/sub>, [latex]{\\text{CO}}_{3}{}^{2-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex], [latex]{\\text{NH}}_{2}^{-}[\/latex]<\/li>\r\n \t<li>H<sub>2<\/sub>SO<sub>4<\/sub>, [latex]{\\text{SO}}_{4}^{2-}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{H}}_{3}{\\text{O}}_{2}^{+}[\/latex], [latex]{\\text{HO}}_{2}^{-}[\/latex]<\/li>\r\n \t<li>H<sub>2<\/sub>S, S<sup>2\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{H}}_{6}{\\text{N}}_{2}{}^{2+}[\/latex], H<sub>4<\/sub>N<sub>2<\/sub><\/li>\r\n<\/ol>\r\n9.\u00a0The labels are Br\u00f8nsted-Lowry acid = BA; its conjugate base = CB; Br\u00f8nsted-Lowry base = BB; its conjugate acid = CA.\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>HNO<sub>3<\/sub>(BA), H<sub>2<\/sub>O(BB), [latex]{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(\\text{CA}\\right)[\/latex], [latex]{\\text{NO}}_{3}{}^{-}\\left(\\text{CB}\\right)[\/latex]<\/li>\r\n \t<li>CN<sup>\u2212<\/sup>(BB), H<sub>2<\/sub>O(BA), HCN(CA), OH<sup>\u2212<\/sup>(CB)<\/li>\r\n \t<li>H<sub>2<\/sub>SO<sub>4<\/sub>(BA), Cl<sup>\u2212<\/sup>(BB), HCl(CA), [latex]{\\text{HSO}}_{4}{}^{-}\\left(\\text{CB}\\right)[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HSO}}_{4}{}^{-}\\left(\\text{BA}\\right)[\/latex], OH<sup>\u2212<\/sup>(BB), [latex]{\\text{SO}}_{4}{}^{\\text{2-}}[\/latex] (CB), H<sub>2<\/sub>O(CA)<\/li>\r\n \t<li>O<sup>2\u2212<\/sup>(BB), H<sub>2<\/sub>O(BA) OH<sup>\u2212<\/sup>(CB and CA)<\/li>\r\n \t<li>[latex]{\\left[{\\text{Cu(H}}_{2}{\\text{O)}}_{3}\\text{(OH)}\\right]}^{\\text{+}}\\text{(BB)}[\/latex], [latex]{\\left[{\\text{Al(H}}_{2}{\\text{O)}}_{6}\\right]}^{3+}\\left(\\text{BA}\\right)[\/latex], [latex]{\\left[\\text{Cu}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{4}\\right]}^{2+}\\left(\\text{CA}\\right)[\/latex], [latex]{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{5}\\left(\\text{OH}\\right)\\right]}^{2+}\\left(\\text{CB}\\right)[\/latex]<\/li>\r\n \t<li>H<sub>2<\/sub>S(BA), [latex]{\\text{NH}}_{2}{}^{-}\\left(\\text{BB}\\right)[\/latex], HS<sup>\u2212<\/sup>(CB), NH<sub>3<\/sub>(CA)<\/li>\r\n<\/ol>\r\n11.\u00a0Amphiprotic species may either gain or lose a proton in a chemical reaction, thus acting as a base or an acid. An example is H<sub>2<\/sub>O. As an acid:\r\n<p style=\"text-align: center;\">[latex]{\\text{H}}_{2}\\text{O}\\left(aq\\right)+{\\text{NH}}_{3}\\left(aq\\right)\\rightleftharpoons {\\text{NH}}_{4}{}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)[\/latex]. As a base: [latex]{\\text{H}}_{2}\\text{O}\\left(aq\\right)+\\text{HCl}\\left(aq\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(aq\\right)+{\\text{Cl}}^{-}\\left(aq\\right)[\/latex]<\/p>\r\n13.\u00a0(a) and (b) are amphiprotic. (c), (d), and (e) are not amphiprotic.\r\n<ol style=\"list-style-type: lower-alpha;\">\r\n \t<li>[latex]{\\text{NH}}_{3}+{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\longrightarrow {\\text{NH}}_{4}\\text{OH}+{\\text{H}}_{2}\\text{O}[\/latex], [latex]{\\text{NH}}_{3}+{\\text{OCH}}_{3}{}^{-}\\longrightarrow {\\text{NH}}_{2}{}^{-}+{\\text{CH}}_{3}\\text{OH}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{HPO}}_{4}{}^{\\text{2-}}+{\\text{OH}}^{-}\\longrightarrow {\\text{PO}}_{4}{}^{\\text{3-}}+{\\text{H}}_{2}\\text{O}[\/latex], [latex]{\\text{HPO}}_{4}{}^{\\text{2-}}+{\\text{HClO}}_{4}\\longrightarrow {\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}+{\\text{ClO}}_{4}{}^{-}[\/latex]<\/li>\r\n \t<li>Br<sup>\u2212<\/sup><\/li>\r\n \t<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\r\n \t<li>[latex]{\\text{AsO}}_{4}^{3-}[\/latex]<\/li>\r\n<\/ol>\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\n<h2>Glossary<\/h2>\r\n<strong>acid ionization: <\/strong>reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid\r\n\r\n<strong>amphiprotic: <\/strong> species that may either gain or lose a proton in a reaction\r\n\r\n<strong>amphoteric:<\/strong> species that can act as either an acid or a base\r\n\r\n<strong>autoionization: <\/strong>reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions\r\n\r\n<strong>base ionization: <\/strong>reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base\r\n\r\n<strong>Br\u00f8nsted-Lowry acid: <\/strong>proton donor\r\n\r\n<strong>Br\u00f8nsted-Lowry base: <\/strong>proton acceptor\r\n\r\n<strong>conjugate acid: <\/strong>substance formed when a base gains a proton\r\n\r\n<strong>conjugate base: <\/strong>substance formed when an acid loses a proton\r\n\r\n<strong>ion-product constant for water (<em>K<\/em><sub>w<\/sub>): <\/strong>equilibrium constant for the autoionization of water","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Identify acids, bases, and conjugate acid-base pairs according to the Br\u00f8nsted-Lowry definition<\/li>\n<li>Write equations for acid and base ionization reactions<\/li>\n<li>Use the ion-product constant for water to calculate hydronium and hydroxide ion concentrations<\/li>\n<li>Describe the acid-base behavior of amphiprotic substances<\/li>\n<\/ul>\n<\/div>\n<p id=\"fs-idm196456848\">The acid-base reaction class has been studied for quite some time. In 1680, Robert\u00a0<span id=\"term570\" class=\"no-emphasis\">Boyle<\/span>\u00a0reported traits of acid solutions that included their ability to dissolve many substances, to change the colors of certain natural dyes, and to lose these traits after coming in contact with alkali (base) solutions. In the eighteenth century, it was recognized that acids have a sour taste, react with limestone to liberate a gaseous substance (now known to be CO<sub>2<\/sub>), and interact with alkalis to form neutral substances. In 1815, Humphry\u00a0<span id=\"term571\" class=\"no-emphasis\">Davy<\/span>\u00a0contributed greatly to the development of the modern acid-base concept by demonstrating that hydrogen is the essential constituent of acids. Around that same time, Joseph Louis Gay-Lussac concluded that acids are substances that can neutralize bases and that these two classes of substances can be defined only in terms of each other. The significance of hydrogen was reemphasized in 1884 when Svante\u00a0<span id=\"term572\" class=\"no-emphasis\">Arrhenius<\/span>\u00a0defined an acid as a compound that dissolves in water to yield hydrogen cations (now recognized to be hydronium ions) and a base as a compound that dissolves in water to yield hydroxide anions.<\/p>\n<p id=\"fs-idm26037424\">Johannes Br\u00f8nsted and Thomas Lowry proposed a more general description in 1923 in which acids and bases were defined in terms of the transfer of hydrogen ions, H<sup>+<\/sup>. (Note that these hydrogen ions are often referred to simply as\u00a0<em>protons<\/em>, since that subatomic particle is the only component of cations derived from the most abundant hydrogen isotope,\u00a0<sup>1<\/sup>H.) A compound that donates a proton to another compound is called a\u00a0<strong>Br\u00f8nsted-Lowry acid<\/strong>, and a compound that accepts a proton is called a\u00a0<strong>Br\u00f8nsted-Lowry base<\/strong>. An acid-base reaction is, thus, the transfer of a proton from a donor (acid) to an acceptor (base).<\/p>\n<p id=\"fs-idm56373376\">The concept of\u00a0<em>conjugate pairs<\/em>\u00a0is useful in describing Br\u00f8nsted-Lowry acid-base reactions (and other reversible reactions, as well). When an acid donates H<sup>+<\/sup>, the species that remains is called the\u00a0<strong>conjugate base<\/strong>\u00a0of the acid because it reacts as a proton acceptor in the reverse reaction. Likewise, when a base accepts H<sup>+<\/sup>, it is converted to its\u00a0<strong>conjugate acid<\/strong>. The reaction between water and ammonia illustrates this idea. In the forward direction, water acts as an acid by donating a proton to ammonia and subsequently becoming a hydroxide ion, OH<sup>\u2212<\/sup>, the conjugate base of water. The ammonia acts as a base in accepting this proton, becoming an ammonium ion,\u00a0<span class=\"os-math-in-para\"><span id=\"MathJax-Element-92-Frame\" class=\"MathJax\" style=\"overflow: initial; font-style: normal; font-weight: normal; line-height: normal; font-size: 14px; text-indent: 0px; text-align: left; letter-spacing: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px;\" role=\"presentation\"><span id=\"MathJax-Span-3014\" class=\"math\"><span id=\"MathJax-Span-3015\" class=\"mrow\"><span id=\"MathJax-Span-3016\" class=\"semantics\"><span id=\"MathJax-Span-3017\" class=\"mrow\"><span id=\"MathJax-Span-3018\" class=\"mrow\"><span id=\"MathJax-Span-3019\" class=\"msup\"><span id=\"MathJax-Span-3020\" class=\"mrow\"><span id=\"MathJax-Span-3021\" class=\"msub\"><span id=\"MathJax-Span-3022\" class=\"mrow\"><span id=\"MathJax-Span-3023\" class=\"mtext\">NH<\/span><\/span><span id=\"MathJax-Span-3024\" class=\"mrow\"><span id=\"MathJax-Span-3025\" class=\"mn\">4<\/span><\/span><\/span><\/span><span id=\"MathJax-Span-3026\" class=\"mrow\"><span id=\"MathJax-Span-3027\" class=\"mtext\">+<\/span><\/span><\/span><span id=\"MathJax-Span-3028\" class=\"mtext\">,<\/span><\/span><\/span><\/span><\/span><\/span><span class=\"MJX_Assistive_MathML\" role=\"presentation\">NH4+,<\/span><\/span><\/span>\u00a0the conjugate acid of ammonia. In the reverse direction, a hydroxide ion acts as a base in accepting a proton from ammonium ion, which acts as an acid.<\/p>\n<p><img decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/05\/23213723\/CNX_Chem_14_01_conjugate_img.jpg\" alt=\"This figure has three parts in two rows. In the first row, two diagrams of acid-base pairs are shown. On the left, a space filling model of H subscript 2 O is shown with a red O atom at the center and two smaller white H atoms attached in a bent shape. Above this model is the label \u201cH subscript 2 O (acid)\u201d in purple. An arrow points right, which is labeled \u201cRemove H superscript plus.\u201d To the right is another space filling model with a single red O atom to which a single smaller white H atom is attached. The label in purple above this model reads, \u201cO H superscript negative (conjugate base).\u201d Above both of these red and white models is an upward pointing bracket that is labeled \u201cConjugate acid-base pair.\u201d To the right is a space filling model with a central blue N atom to which three smaller white H atoms are attached in a triangular pyramid arrangement. A label in green above reads \u201cN H subscript 3 (base).\u201d An arrow labeled \u201cAdd H superscript plus\u201d points right. To the right of the arrow is another space filling model with a blue central N atom and four smaller white H atoms in a tetrahedral arrangement. The green label above reads \u201cN H subscript 3 superscript plus (conjugate acid).\u201d Above both of these blue and white models is an upward pointing bracket that is labeled \u201cConjugate acid-base pair.\u201d The second row of the figure shows the chemical reaction, H subscript 2 O ( l ) is shown in purple, and is labeled below in purple as \u201cacid,\u201d plus N H subscript 3 (a q) in green, labeled below in green as \u201cbase,\u201d followed by a double sided arrow arrow and O H superscript negative (a q) in purple, labeled in purple as \u201cconjugate base,\u201d plus N H subscript 4 superscript plus (a q)\u201d in green, which is labeled in green as \u201cconjugate acid.\u201d The acid on the left side of the equation is connected to the conjugate base on the right with a purple line. Similarly, the base on the left is connected to the conjugate acid on the right side.\" \/><\/p>\n<p>The reaction between a Br\u00f8nsted-Lowry acid and water is called <strong>acid ionization<\/strong>. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/openstax.org\/resources\/1f9a8c21ac9da03aa5517b79f0d772d3f8fbb920\" alt=\"This figure has two rows. In both rows, a chemical reaction is shown. In the first, structural formulas are provided. In this model, in red, is an O atom which has H atoms singly bonded above and to the right. The O atom has lone pairs of electron dots on its left and lower sides. This is followed by a plus sign. The plus sign is followed, in blue, by an N atom with one lone pair of electron dots. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. An equilibrium arrow follows this structure. To the right, in brackets is a structure where an N atom bonded to an H atom, which is red, appears. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. Outside the brackets, to the right, is a superscript positive sign. This structure is followed by a plus sign. Another structure that appears in brackets also appears. An O atom with three lone pairs of electron dots is bonded to an H atom. There is a superscript negative sign outside the brackets. Under the initial equation, is this equation: H subscript 2 plus C subscript 5 N H subscript 5 equilibrium arrow C subscript 5 N H subscript 6 superscript positive sign plus O H superscript negative sign. H subscript 2 O is labeled, \u201cacid,\u201d in red. C subscript 5 N H subscript 5 is labeled, \u201cbase,\u201d in blue. C subscript 5 N H subscript 6 superscript positive sign is labeled, \u201cacid\u201d in blue. O H superscript negative sign is labeled, \u201cbase,\u201d in red.\" width=\"726\" height=\"233\" \/><\/p>\n<p><strong><span id=\"term576\">Base ionization<\/span><\/strong>\u00a0of a species occurs when it accepts protons from water molecules. In the example below, pyridine molecules, C<sub>5<\/sub>NH<sub>5<\/sub>, undergo base ionization when dissolved in water, yielding hydroxide and pyridinium ions:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/openstax.org\/resources\/b523238d04bf275f461c36ececbc297f34fe7181\" alt=\"This figure has two rows. In both rows, a chemical reaction is shown. In the first, structural formulas are provided. In this model, in red, is an O atom which has H atoms singly bonded above and to the right. The O atom has lone pairs of electron dots on its left and lower sides. This is followed by a plus sign. The plus sign is followed, in blue, by an N atom with one lone pair of electron dots. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. An equilibrium arrow follows this structure. To the right, in brackets is a structure where an N atom bonded to an H atom, which is red, appears. The N atom forms a double bond with a C atom, which forms a single bond with a C atom. The second C atom forms a double bond with another C atom, which forms a single bond with another C atom. The fourth C atom forms a double bond with a fifth C atom, which forms a single bond with the N atom. This creates a ring structure. Each C atom is also bonded to an H atom. Outside the brackets, to the right, is a superscript positive sign. This structure is followed by a plus sign. Another structure that appears in brackets also appears. An O atom with three lone pairs of electron dots is bonded to an H atom. There is a superscript negative sign outside the brackets. To the right, is the equation: k equals [ C subscript 5 N H subscript 6 superscript positive sign ] [ O H superscript negative sign] all divided by [ C subscript 5 N H subscript 5 ]. Under the initial equation, is this equation: H subscript 2 plus C subscript 5 N H subscript 5 equilibrium arrow C subscript 5 N H subscript 6 superscript positive sign plus O H superscript negative sign. H subscript 2 O is labeled, \u201cacid,\u201d in red. C subscript 5 N H subscript 5 is labeled, \u201cbase,\u201d in blue. C subscript 5 N H subscript 6 superscript positive sign is labeled, \u201cacid\u201d in blue. O H superscript negative sign is labeled, \u201cbase,\u201d in red.\" width=\"727\" height=\"251\" \/><\/p>\n<p>The preceding ionization reactions suggest that water may function as both a base (as in its reaction with hydrogen fluoride) and an acid (as in its reaction with ammonia). Species capable of either donating or accepting protons are called\u00a0<strong><span id=\"term577\">amphiprotric<\/span><\/strong>, or more generally,\u00a0<strong><span id=\"term578\">amphoteric<\/span><\/strong>, a term that may be used for acids and bases per definitions other than the Br\u00f8nsted-Lowry one. The equations below show the two possible acid-base reactions for two amphiprotic species, bicarbonate ion and water:<\/p>\n<p class=\"p1\" style=\"text-align: center;\">[latex]{\\text{HCO}_{3}}^{-}(\\text{aq})+\\text{H}_{2}\\text{O}(\\text{l})\\qquad{\\text{CO}_{3}}^{2-}(\\text{aq})+\\text{H}_{3}\\text{O}^{+}(\\text{aq})[\/latex]<span id=\"MathJax-Element-93-Frame\" class=\"MathJax\" style=\"overflow: initial; font-style: normal; font-weight: normal; line-height: normal; font-size: 14px; text-indent: 0px; text-align: center; letter-spacing: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px;\" role=\"presentation\"><\/span><\/p>\n<p style=\"text-align: center;\">[latex]{\\text{HCO}_{3}}^{-}(\\text{aq})+\\text{H}_{2}\\text{O}(\\text{l})\\qquad\\text{H}_{2}\\text{CO}  _{3}(\\text{aq})+\\text{OH}^{-}(\\text{aq})[\/latex]<\/p>\n<p>The first equation represents the reaction of bicarbonate as an acid with water as a base, whereas the second represents reaction of bicarbonate as a base with water as an acid. When bicarbonate is added to water, both these equilibria are established simultaneously and the composition of the resulting solution may be determined through appropriate equilibrium calculations, as described later in this chapter.<\/p>\n<p id=\"fs-idm206801664\">In the liquid state, molecules of an amphiprotic substance can react with one another as illustrated for water in the equations below:<\/p>\n<p><img decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/05\/23213728\/CNX_Chem_14_01_Water_img.jpg\" alt=\"This figure has two rows. In both rows, a chemical reaction is shown. In the first, structural formulas are provided. In this model, in purple, O atom which has H atoms singly bonded above and to the right. The O atom has pairs of electron dots on its left and lower sides. This is followed by a plus sign, which is followed in green by an O atom which has H atoms singly bonded above and to the right. The O atom has pairs of electron dots on its left and lower sides. A double arrow follows. To the right, in brackets is a structure with a central O atom in green, with green H atoms singly bonded above and to the right. A pair of green electron dots is on the lower side of the O atom. To the left of the green O atom, a purple H atom is singly bonded. Outside the brackets to the right is a superscript plus. This is followed by a plus sign and an O atom in purple with pairs of electron dots above, left, and below. An H atom is singly bonded to the right. This atom has a superscript negative sign. The reaction is written in symbolic form below. H subscript 2 O is labeled in purple below as \u201cAcid subscript 1.\u201d This is followed by plus H subscript 2 O, which is labeled in green below as \u201cBase subscript 2.\u201d A double sided arrow follows. To the right is H subscript 3 O superscript plus, which is labeled in green as below in as \u201cAcid subscript 2.\u201d This is followed by plus and O with pairs of dots above, below, and to the left with a singly bonded H on the right with a superscript negative. The label below in purple reads, \u201c Base subscript 1.\u201d\" \/><\/p>\n<p>The process in which like molecules react to yield ions is called\u00a0<strong><span id=\"term579\">autoionization<\/span><\/strong>. Liquid water undergoes autoionization to a very slight extent; at 25 \u00b0C, approximately two out of every billion water molecules are ionized. The extent of the water autoionization process is reflected in the value of its equilibrium constant, the\u00a0<strong><span id=\"term580\">ion-product constant for water,\u00a0<em>K<\/em><sub>w<\/sub><\/span><\/strong>:<\/p>\n<p style=\"text-align: center;\">[latex]{\\text{H}}_{2}\\text{O}\\left(l\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\qquad{K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right][\/latex]<\/p>\n<p>The slight ionization of pure water is reflected in the small value of the equilibrium constant; at 25 \u00b0C, <em>K<\/em><sub>w<\/sub> has a value of 1.0 [latex]\\times[\/latex] 10<sup>\u221214<\/sup>. The process is endothermic, and so the extent of ionization and the resulting concentrations of hydronium ion and hydroxide ion increase with temperature. For example, at 100 \u00b0C, the value for <em>K<\/em><sub>w<\/sub> is about 5.1 [latex]\\times[\/latex] 10<sup>\u221213<\/sup>, roughly 100-times larger than the value at 25 \u00b0C.<\/p>\n<div class=\"textbox examples\">\n<h3>Example 1:\u00a0Ion Concentrations in Pure Water<\/h3>\n<p>What are the hydronium ion concentration and the hydroxide ion concentration in pure water at 25 \u00b0C?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q160586\">Show Solution<\/span><\/p>\n<div id=\"q160586\" class=\"hidden-answer\" style=\"display: none\">\n<p>The autoionization of water yields the same number of hydronium and hydroxide ions. Therefore, in pure water, [latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=\\left[\\text{OH}^{-}\\right][\/latex]. At 25 \u00b0C: [latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]={\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]}^{\\text{2+}}={\\left[{\\text{OH}}^{-}\\right]}^{\\text{2+}}=1.0\\times {10}^{-14}[\/latex]<\/p>\n<p>So:<\/p>\n<p style=\"text-align: center;\">[latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=\\left[{\\text{OH}}^{-}\\right]=\\sqrt{1.0\\times {10}^{-14}}=1.0\\times {10}^{-7}M[\/latex]<\/p>\n<p>The hydronium ion concentration and the hydroxide ion concentration are the same, and we find that both equal 1.0\u00a0\u00d7\u00a010<sup>\u22127<\/sup><em>M<\/em>.<\/p>\n<\/div>\n<\/div>\n<h4>Check Your Learning<\/h4>\n<p>The ion product of water at 80 \u00b0C is 2.4\u00a0\u00d7\u00a010<sup>\u221213<\/sup>. What are the concentrations of hydronium and hydroxide ions in pure water at 80 \u00b0C?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q709034\">Show Solution<\/span><\/p>\n<div id=\"q709034\" class=\"hidden-answer\" style=\"display: none\">[latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=\\left[\\text{OH}^{-}\\right]=4.9\\times 10^{-7}M[\/latex]<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox examples\">\n<h3>Example 2:\u00a0The Inverse Proportionality of [H<sub>3<\/sub>O<sup>+<\/sup>] and [OH<sup>\u2212<\/sup>]<\/h3>\n<p>A solution of carbon dioxide in water has a hydronium ion concentration of 2.0 [latex]\\times[\/latex] 10<sup>\u22126<\/sup><em>M<\/em>. What is the concentration of hydroxide ion at 25 \u00b0C?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q647487\">Show Solution<\/span><\/p>\n<div id=\"q647487\" class=\"hidden-answer\" style=\"display: none\">\n<p>We know the value of the ion-product constant for water at 25 \u00b0C:<\/p>\n<p style=\"text-align: center;\">[latex]2{\\text{H}}_{2}\\text{O}\\left(l\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right){K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=1.0\\times {10}^{-14}[\/latex]<\/p>\n<p>Thus, we can calculate the missing equilibrium concentration.<\/p>\n<p>Rearrangement of the <em>K<\/em><sub>w<\/sub> expression yields that [OH<sup>\u2212<\/sup>] is directly proportional to the inverse of [latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right][\/latex]:<\/p>\n<p style=\"text-align: center;\">[latex]\\left[{\\text{OH}}^{-}\\right]=\\dfrac{{K}_{\\text{w}}}{\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]}=\\dfrac{1.0\\times {10}^{-14}}{2.0\\times {10}^{-6}}=5.0\\times {10}^{-9}[\/latex]<\/p>\n<p>The hydroxide ion concentration in water is reduced to 5.0 [latex]\\times[\/latex] 10<sup>\u22129<\/sup><em>M<\/em> as the hydrogen ion concentration increases to 2.0 [latex]\\times[\/latex] 10<sup>\u22126<\/sup><em>M<\/em>. This is expected from Le Ch\u00e2telier\u2019s principle; the autoionization reaction shifts to the left to reduce the stress of the increased hydronium ion concentration and the [OH<sup>\u2212<\/sup>] is reduced relative to that in pure water.<\/p>\n<p>A check of these concentrations confirms that our arithmetic is correct:<\/p>\n<p style=\"text-align: center;\">[latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=\\left(2.0\\times {10}^{-6}\\right)\\left(5.0\\times {10}^{-9}\\right)=1.0\\times {10}^{-14}[\/latex]<\/p>\n<\/div>\n<\/div>\n<h4>Check Your Learning<\/h4>\n<p>What is the hydronium ion concentration in an aqueous solution with a hydroxide ion concentration of 0.001 <em>M<\/em> at 25 \u00b0C?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q366443\">Show Solution<\/span><\/p>\n<div id=\"q366443\" class=\"hidden-answer\" style=\"display: none\">[latex]\\left[{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\right]=1\\times 10^{-11}M[\/latex]<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox examples\">\n<h3>Example 3:\u00a0Representing the Acid-Base Behavior of an Amphoteric Substance<\/h3>\n<p>Write separate equations representing the reaction of [latex]{\\text{HSO}}_{3}^{-}[\/latex]<\/p>\n<ol>\n<li>as an acid with OH<sup>\u2212<\/sup><\/li>\n<li>as a base with HI<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q236960\">Show Solution<\/span><\/p>\n<div id=\"q236960\" class=\"hidden-answer\" style=\"display: none\">\n<ol>\n<li>[latex]{\\text{HSO}}_{3}^{-}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\rightleftharpoons {\\text{SO}}_{3}^{2-}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\n<li>[latex]{\\text{HSO}}_{3}^{-}\\left(aq\\right)+\\text{HI}\\left(aq\\right)\\rightleftharpoons {\\text{H}}_{2}{\\text{SO}}_{3}\\left(aq\\right)+{\\text{I}}^{-}\\left(aq\\right)[\/latex]<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<h4>Check Your Learning<\/h4>\n<p>Write separate equations representing the reaction of [latex]{\\text{H}}_{2}{\\text{PO}}_{4}^{-}[\/latex]<\/p>\n<ol>\n<li>as a base with HBr<\/li>\n<li>as an acid with OH<sup>\u2212<\/sup><\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q161818\">Show Solution<\/span><\/p>\n<div id=\"q161818\" class=\"hidden-answer\" style=\"display: none\">\n<ol>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}\\left(aq\\right)+\\text{HBr}\\left(aq\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{PO}}_{4}\\left(aq\\right)+{\\text{Br}}^{-}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\rightleftharpoons {\\text{HPO}}_{4}{}^{\\text{2-}}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Key Concepts and Summary<\/h3>\n<p>A compound that can donate a proton (a hydrogen ion) to another compound is called a Br\u00f8nsted-Lowry acid. The compound that accepts the proton is called a Br\u00f8nsted-Lowry base. The species remaining after a Br\u00f8nsted-Lowry acid has lost a proton is the conjugate base of the acid. The species formed when a Br\u00f8nsted-Lowry base gains a proton is the conjugate acid of the base. Thus, an acid-base reaction occurs when a proton is transferred from an acid to a base, with formation of the conjugate base of the reactant acid and formation of the conjugate acid of the reactant base. Amphiprotic species can act as both proton donors and proton acceptors. Water is the most important amphiprotic species. It can form both the hydronium ion, [latex]{\\text{H}}_{3}{\\text{O}}^{\\text{+}}[\/latex], and the hydroxide ion, OH<sup>\u2212<\/sup> when it undergoes autoionization:<\/p>\n<p style=\"text-align: center;\">[latex]{\\text{2H}}_{2}\\text{O}\\left(l\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{+}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)[\/latex]<\/p>\n<p>The ion product of water, <em>K<\/em><sub>w<\/sub> is the equilibrium constant for the autoionization reaction:<\/p>\n<p style=\"text-align: center;\">[latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{2}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=1.0\\times 1{0}^{-14}\\text{ at }25^{\\circ}\\text{C}[\/latex]<\/p>\n<h4>Key Equations<\/h4>\n<ul>\n<li>[latex]{K}_{\\text{w}}=\\left[{\\text{H}}_{2}{\\text{O}}^{\\text{+}}\\right]\\left[{\\text{OH}}^{-}\\right]=1.0\\times 1{0}^{-14}\\text{ at }25^{\\circ}\\text{C}[\/latex]<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Try It<\/h3>\n<ol>\n<li>Write equations that show NH<sub>3<\/sub> as both a conjugate acid and a conjugate base.<\/li>\n<li>Write equations that show [latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex] acting both as an acid and as a base.<\/li>\n<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry acid:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]{\\text{H}}_{3}{\\text{O}}^{\\text{+}}[\/latex]<\/li>\n<li>HCl<\/li>\n<li>NH<sub>3<\/sub><\/li>\n<li>CH<sub>3<\/sub>CO<sub>2<\/sub>H<\/li>\n<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\n<li>[latex]{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry acid:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>HNO<sub>3<\/sub><\/li>\n<li>[latex]{\\text{PH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\n<li>H<sub>2<\/sub>S<\/li>\n<li>CH<sub>3<\/sub>CH<sub>2<\/sub>COOH<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\n<li>HS<sup>\u2212<\/sup><\/li>\n<\/ol>\n<\/li>\n<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry base:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>H<sub>2<\/sub>O<\/li>\n<li>OH<sup>\u2212<\/sup><\/li>\n<li>NH<sub>3<\/sub><\/li>\n<li>CN<sup>\u2212<\/sup><\/li>\n<li>S<sup>2\u2212<\/sup><\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>Show by suitable net ionic equations that each of the following species can act as a Br\u00f8nsted-Lowry base:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>HS<sup>\u2212<\/sup><\/li>\n<li>[latex]{\\text{PO}}_{4}{}^{\\text{3-}}[\/latex]<\/li>\n<li>[latex]{\\text{NH}}_{2}{}^{-}[\/latex]<\/li>\n<li>C<sub>2<\/sub>H<sub>5<\/sub>OH<\/li>\n<li>O<sup>2\u2212<\/sup><\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>What is the conjugate acid of each of the following? What is the conjugate base of each?\n<ol style=\"list-style-type: lower-alpha;\">\n<li>OH<sup>\u2212<\/sup><\/li>\n<li>H<sub>2<\/sub>O<\/li>\n<li>[latex]{\\text{HCO}}_{3}{}^{-}[\/latex]<\/li>\n<li>NH<sub>3<\/sub><\/li>\n<li>[latex]{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\n<li>H<sub>2<\/sub>O<sub>2<\/sub><\/li>\n<li>HS<sup>\u2212<\/sup><\/li>\n<li>[latex]{\\text{H}}_{5}{\\text{N}}_{2}{}^{\\text{+}}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>What is the conjugate acid of each of the following? What is the conjugate base of each?\n<ol style=\"list-style-type: lower-alpha;\">\n<li>H<sub>2<\/sub>S<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\n<li>PH<sub>3<\/sub><\/li>\n<li>HS<sup>\u2212<\/sup><\/li>\n<li>[latex]{\\text{HSO}}_{3}{}^{-}[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{3}{\\text{O}}_{2}{}^{\\text{+}}[\/latex]<\/li>\n<li>H<sub>4<\/sub>N<sub>2<\/sub><\/li>\n<li>CH<sub>3<\/sub>OH<\/li>\n<\/ol>\n<\/li>\n<li>Identify and label the Br\u00f8nsted-Lowry acid, its conjugate base, the Br\u00f8nsted-Lowry base, and its conjugate acid in each of the following equations:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]{\\text{HNO}}_{3}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{H}}_{3}{\\text{O}}^{\\text{+}}+{\\text{NO}}_{3}{}^{-}[\/latex]<\/li>\n<li>[latex]{\\text{CN}}^{-}+{\\text{H}}_{2}\\text{O}\\longrightarrow \\text{HCN}+{\\text{OH}}^{-}[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{SO}}_{4}+{\\text{Cl}}^{-}\\longrightarrow \\text{HCl}+{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\n<li>[latex]{\\text{HSO}}_{4}{}^{-}+{\\text{OH}}^{-}\\longrightarrow {\\text{SO}}_{4}{}^{\\text{2-}}+{\\text{H}}_{2}\\text{O}[\/latex]<\/li>\n<li>[latex]{\\text{O}}^{2-}+{\\text{H}}_{2}\\text{O}\\longrightarrow 2{\\mathrm{OH}}^{-}[\/latex]<\/li>\n<li>[latex]{\\left[\\text{Cu}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{3}\\left(\\text{OH}\\right)\\right]}^{\\text{+}}+{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{6}\\right]}^{3+}\\longrightarrow {\\left[\\text{Cu}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{4}\\right]}^{2+}+{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{5}\\left(\\text{OH}\\right)\\right]}^{2+}[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{2}\\text{S}+{\\text{NH}}_{2}{}^{-}\\longrightarrow {\\text{HS}}^{-}+{\\text{NH}}_{3}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>Identify and label the Br\u00f8nsted-Lowry acid, its conjugate base, the Br\u00f8nsted-Lowry base, and its conjugate acid in each of the following equations:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]{\\text{NO}}_{2}{}^{-}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{HNO}}_{2}+{\\text{OH}}^{-}[\/latex]<\/li>\n<li>[latex]\\text{HBr}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{H}}_{3}{\\text{O}}^{\\text{+}}+{\\text{Br}}^{-}[\/latex]<\/li>\n<li>[latex]{\\text{HS}}^{-}+{\\text{H}}_{2}\\text{O}\\longrightarrow {\\text{H}}_{2}\\text{S}+{\\text{OH}}^{-}[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}+{\\text{OH}}^{-}\\longrightarrow {\\text{HPO}}_{4}{}^{\\text{2-}}+{\\text{H}}_{2}\\text{O}[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}+\\text{HCl}\\longrightarrow {\\text{H}}_{3}{\\text{PO}}_{4}+{\\text{Cl}}^{-}[\/latex]<\/li>\n<li>[latex]\\left[\\text{Fe}\\left(\\text{H}_{2}\\text{O}\\right)_{5}\\left(\\text{OH}\\right)\\right]^{2+}+\\left[\\text{Al}\\left(\\text{H}_{2}\\text{O}\\right)_6\\right]^{3+}\\longrightarrow\\left[\\text{Fe}\\left(\\text{H}_{2}\\text{O}\\right)_{6}\\right]^{3+}+\\left[\\text{Al}\\left(\\text{H}_2\\text{O}\\right)_5\\left(\\text{OH}\\right)\\right]^{2+}[\/latex]<\/li>\n<li>[latex]{\\text{CH}}_{3}\\text{OH}+{\\text{H}}^{-}\\longrightarrow {\\text{CH}}_{3}{\\text{O}}^{-}+{\\text{H}}_{2}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>What are amphiprotic species? Illustrate with suitable equations.<\/li>\n<li>State which of the following species are amphiprotic and write chemical equations illustrating the amphiprotic character of these species:\n<ol style=\"list-style-type: lower-alpha;\">\n<li>H<sub>2<\/sub>O<\/li>\n<li>[latex]{\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}[\/latex]<\/li>\n<li>S<sup>2\u2212<\/sup><\/li>\n<li>[latex]{\\text{CO}}_{3}{}^{\\text{2-}}[\/latex]<\/li>\n<li>[latex]{\\text{HSO}}_{4}{}^{-}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>State which of the following species are amphiprotic and write chemical equations illustrating the amphiprotic character of these species.\n<ol style=\"list-style-type: lower-alpha;\">\n<li>NH<sub>3<\/sub><\/li>\n<li>[latex]{\\text{HPO}}_{4}{}^{-}[\/latex]<\/li>\n<li>Br<sup>\u2212<\/sup><\/li>\n<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\n<li>[latex]{\\text{ASO}}_{4}{}^{\\text{3-}}[\/latex]<\/li>\n<\/ol>\n<\/li>\n<li>Is the self ionization of water endothermic or exothermic? The ionization constant for water (<em>K<\/em><sub>w<\/sub>) is 2.9 [latex]\\times[\/latex] 10<sup>\u221214<\/sup> at 40 \u00b0C and 9.6 [latex]\\times[\/latex] 10<sup>\u221214<\/sup> at 60 \u00b0C.<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q41360\">Show Selected Solutions<\/span><\/p>\n<div id=\"q41360\" class=\"hidden-answer\" style=\"display: none\">\n<p>1.\u00a0One example for NH<sub>3<\/sub> as a conjugate acid: [latex]{\\text{NH}}_{2}{}^{-}+{\\text{H}}^{\\text{+}}\\longrightarrow {\\text{NH}}_{3}[\/latex]; as a conjugate base: [latex]{\\text{NH}}_{4}{}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)\\longrightarrow {\\text{NH}}_{3}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/p>\n<p>3. The net ionic equations are as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]{\\text{H}}_{3}{\\text{O}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\n<li>[latex]\\text{HCl}\\left(l\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{Cl}}^{-}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{NH}}_{3}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{NH}}_{2}^{-}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{CH}}_{3}{\\text{CO}}_{2}\\text{H}\\left(aq\\right)\\longrightarrow {\\text{H}}^{\\text{+}}\\left(aq\\right)+{\\text{CH}}_{3}{\\text{CO}}_{2}^{-}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{NH}}_{3}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{HSO}}_{4}{}^{-}\\left(aq\\right)\\longrightarrow {\\text{H}}^{+}\\left(aq\\right)+{\\text{SO}}_{4}^{2-}\\left(aq\\right)[\/latex]<\/li>\n<\/ol>\n<p>5. The net ionic equations are as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]{\\text{H}}_{2}\\text{O}\\left(l\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}_{3}{\\text{O}}^{+}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{OH}}^{-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}_{2}\\text{O}\\left(l\\right)[\/latex]<\/li>\n<li>[latex]{\\text{NH}}_{3}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{NH}}_{4}^{+}\\left(aq\\right)[\/latex]<\/li>\n<li>[latex]{\\text{CN}}^{-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow\\text{HCN}\\left(aq\\right)[\/latex]<\/li>\n<li>(e) [latex]{\\text{S}}^{2-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{HS}}^{-}\\left(aq\\right)[\/latex]<\/li>\n<li>(f) [latex]{\\text{H}}_{2}{\\text{PO}}_{4}^{-}\\left(aq\\right)+{\\text{H}}^{+}\\left(aq\\right)\\longrightarrow {\\text{H}}_{3}{\\text{PO}}_{4}\\left(aq\\right)[\/latex]<\/li>\n<\/ol>\n<p>7.\u00a0The conjugate acids and bases are as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>H<sub>2<\/sub>O, O<sup>2\u2212<\/sup><\/li>\n<li>[latex]{\\text{H}}_{3}{\\text{O}}^{+}[\/latex], OH<sup>\u2212<\/sup><\/li>\n<li>H<sub>2<\/sub>CO<sub>3<\/sub>, [latex]{\\text{CO}}_{3}{}^{2-}[\/latex]<\/li>\n<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex], [latex]{\\text{NH}}_{2}^{-}[\/latex]<\/li>\n<li>H<sub>2<\/sub>SO<sub>4<\/sub>, [latex]{\\text{SO}}_{4}^{2-}[\/latex]<\/li>\n<li>[latex]{\\text{H}}_{3}{\\text{O}}_{2}^{+}[\/latex], [latex]{\\text{HO}}_{2}^{-}[\/latex]<\/li>\n<li>H<sub>2<\/sub>S, S<sup>2\u2212<\/sup><\/li>\n<li>[latex]{\\text{H}}_{6}{\\text{N}}_{2}{}^{2+}[\/latex], H<sub>4<\/sub>N<sub>2<\/sub><\/li>\n<\/ol>\n<p>9.\u00a0The labels are Br\u00f8nsted-Lowry acid = BA; its conjugate base = CB; Br\u00f8nsted-Lowry base = BB; its conjugate acid = CA.<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>HNO<sub>3<\/sub>(BA), H<sub>2<\/sub>O(BB), [latex]{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(\\text{CA}\\right)[\/latex], [latex]{\\text{NO}}_{3}{}^{-}\\left(\\text{CB}\\right)[\/latex]<\/li>\n<li>CN<sup>\u2212<\/sup>(BB), H<sub>2<\/sub>O(BA), HCN(CA), OH<sup>\u2212<\/sup>(CB)<\/li>\n<li>H<sub>2<\/sub>SO<sub>4<\/sub>(BA), Cl<sup>\u2212<\/sup>(BB), HCl(CA), [latex]{\\text{HSO}}_{4}{}^{-}\\left(\\text{CB}\\right)[\/latex]<\/li>\n<li>[latex]{\\text{HSO}}_{4}{}^{-}\\left(\\text{BA}\\right)[\/latex], OH<sup>\u2212<\/sup>(BB), [latex]{\\text{SO}}_{4}{}^{\\text{2-}}[\/latex] (CB), H<sub>2<\/sub>O(CA)<\/li>\n<li>O<sup>2\u2212<\/sup>(BB), H<sub>2<\/sub>O(BA) OH<sup>\u2212<\/sup>(CB and CA)<\/li>\n<li>[latex]{\\left[{\\text{Cu(H}}_{2}{\\text{O)}}_{3}\\text{(OH)}\\right]}^{\\text{+}}\\text{(BB)}[\/latex], [latex]{\\left[{\\text{Al(H}}_{2}{\\text{O)}}_{6}\\right]}^{3+}\\left(\\text{BA}\\right)[\/latex], [latex]{\\left[\\text{Cu}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{4}\\right]}^{2+}\\left(\\text{CA}\\right)[\/latex], [latex]{\\left[\\text{Al}{\\left({\\text{H}}_{2}\\text{O}\\right)}_{5}\\left(\\text{OH}\\right)\\right]}^{2+}\\left(\\text{CB}\\right)[\/latex]<\/li>\n<li>H<sub>2<\/sub>S(BA), [latex]{\\text{NH}}_{2}{}^{-}\\left(\\text{BB}\\right)[\/latex], HS<sup>\u2212<\/sup>(CB), NH<sub>3<\/sub>(CA)<\/li>\n<\/ol>\n<p>11.\u00a0Amphiprotic species may either gain or lose a proton in a chemical reaction, thus acting as a base or an acid. An example is H<sub>2<\/sub>O. As an acid:<\/p>\n<p style=\"text-align: center;\">[latex]{\\text{H}}_{2}\\text{O}\\left(aq\\right)+{\\text{NH}}_{3}\\left(aq\\right)\\rightleftharpoons {\\text{NH}}_{4}{}^{\\text{+}}\\left(aq\\right)+{\\text{OH}}^{-}\\left(aq\\right)[\/latex]. As a base: [latex]{\\text{H}}_{2}\\text{O}\\left(aq\\right)+\\text{HCl}\\left(aq\\right)\\rightleftharpoons {\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\left(aq\\right)+{\\text{Cl}}^{-}\\left(aq\\right)[\/latex]<\/p>\n<p>13.\u00a0(a) and (b) are amphiprotic. (c), (d), and (e) are not amphiprotic.<\/p>\n<ol style=\"list-style-type: lower-alpha;\">\n<li>[latex]{\\text{NH}}_{3}+{\\text{H}}_{3}{\\text{O}}^{\\text{+}}\\longrightarrow {\\text{NH}}_{4}\\text{OH}+{\\text{H}}_{2}\\text{O}[\/latex], [latex]{\\text{NH}}_{3}+{\\text{OCH}}_{3}{}^{-}\\longrightarrow {\\text{NH}}_{2}{}^{-}+{\\text{CH}}_{3}\\text{OH}[\/latex]<\/li>\n<li>[latex]{\\text{HPO}}_{4}{}^{\\text{2-}}+{\\text{OH}}^{-}\\longrightarrow {\\text{PO}}_{4}{}^{\\text{3-}}+{\\text{H}}_{2}\\text{O}[\/latex], [latex]{\\text{HPO}}_{4}{}^{\\text{2-}}+{\\text{HClO}}_{4}\\longrightarrow {\\text{H}}_{2}{\\text{PO}}_{4}{}^{-}+{\\text{ClO}}_{4}{}^{-}[\/latex]<\/li>\n<li>Br<sup>\u2212<\/sup><\/li>\n<li>[latex]{\\text{NH}}_{4}{}^{\\text{+}}[\/latex]<\/li>\n<li>[latex]{\\text{AsO}}_{4}^{3-}[\/latex]<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n<h2>Glossary<\/h2>\n<p><strong>acid ionization: <\/strong>reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid<\/p>\n<p><strong>amphiprotic: <\/strong> species that may either gain or lose a proton in a reaction<\/p>\n<p><strong>amphoteric:<\/strong> species that can act as either an acid or a base<\/p>\n<p><strong>autoionization: <\/strong>reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions<\/p>\n<p><strong>base ionization: <\/strong>reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base<\/p>\n<p><strong>Br\u00f8nsted-Lowry acid: <\/strong>proton donor<\/p>\n<p><strong>Br\u00f8nsted-Lowry base: <\/strong>proton acceptor<\/p>\n<p><strong>conjugate acid: <\/strong>substance formed when a base gains a proton<\/p>\n<p><strong>conjugate base: <\/strong>substance formed when an acid loses a proton<\/p>\n<p><strong>ion-product constant for water (<em>K<\/em><sub>w<\/sub>): <\/strong>equilibrium constant for the autoionization of water<\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-3445\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Chemistry 2e. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/openstax.org\/\">https:\/\/openstax.org\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/chemistry-2e\/pages\/1-introduction<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":2,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Chemistry 2e\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"https:\/\/openstax.org\/\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Access for free at https:\/\/openstax.org\/books\/chemistry-2e\/pages\/1-introduction\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-3445","chapter","type-chapter","status-publish","hentry"],"part":2988,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/chapters\/3445","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":13,"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/chapters\/3445\/revisions"}],"predecessor-version":[{"id":7842,"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/chapters\/3445\/revisions\/7842"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/parts\/2988"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/chapters\/3445\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/wp\/v2\/media?parent=3445"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/pressbooks\/v2\/chapter-type?post=3445"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/wp\/v2\/contributor?post=3445"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/chemistryformajors\/wp-json\/wp\/v2\/license?post=3445"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}