{"id":248,"date":"2017-08-21T04:49:40","date_gmt":"2017-08-21T04:49:40","guid":{"rendered":"http:\/\/americanboard.org\/Subjects\/chemistry\/?page_id=248"},"modified":"2017-09-19T17:09:46","modified_gmt":"2017-09-19T17:09:46","slug":"acids-and-oxides","status":"publish","type":"page","link":"https:\/\/americanboard.org\/Subjects\/chemistry\/acids-and-oxides\/","title":{"rendered":"Acids and Oxides"},"content":{"rendered":"<div class=\"twelve columns\" style=\"margin-top: 10%;\">\n<div class=\"advance\">\n<p><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/writing-names-and-formulas\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/chemical-naming-and-structure\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/percent-composition-and-formulas\">Next Lesson \u27a1<\/a><\/p>\n<\/div>\n<p><!-- UPDATE NEXT\/PREVIOUS ABOVE --><\/p>\n<p><!-- CONTENT STARTS HERE --><\/p>\n<h1 id=\"title\">Acids and Oxides<\/h1>\n<h4>Objective<\/h4>\n<p>In this lesson we will review chemical names and formulas for acids. We will also review the acid\/base properties of oxides.<\/p>\n<h4>Previously we covered&#8230;<\/h4>\n<ul>\n<li>Oxidation numbers may be used in situations when true charges may not apply<\/li>\n<li>Oxidation numbers may be assigned using the following rules:\n<ul>\n<li>Elements are zero.<\/li>\n<li>Hydrogen and oxygen in compounds are +1 and \u22122, respectively.<\/li>\n<li>Monatomic ions are equal to their charges.<\/li>\n<\/ul>\n<\/li>\n<li>Molecular compounds are named with prefixes, such as \u201cmono-,\u201d \u201cdi-,\u201d etc.<\/li>\n<li>Ionic compounds are named by naming the positive ion followed by the name of the negative ion.<\/li>\n<li>Monatomic negative ions end with \u201c-ide,\u201d\u00a0while polyatomic negative ions usually end with \u201c-ite\u201d or\u00a0\u201c-ate.\u201d<\/li>\n<li>An ionic formula is the lowest whole number ratio of ions whose charges add up to zero.<\/li>\n<li>If there is more than one polyatomic ion in a formula, its formula must be in parentheses with the subscript outside.<\/li>\n<\/ul>\n<section>\n<h3>Acids<\/h3>\n<p>Although there are multiple theories regarding what constitutes an acid and a base, the two theories most commonly used in the chemistry classroom and laboratory are the Arrhenius theory and the Bronstedt-Lowry theory. They agree on this point: an acid must contain hydrogen ions, H<sup>+<\/sup>. Because acids are compounds and therefore must be electrically neutral, they are required to have an <abbr title=\"A negative ion\">anion<\/abbr> with them.<\/p>\n<p>Remembering this makes writing names and formulas for acids relatively simple, in that all acids will contain the same <abbr title=\"A positively charged ion\">cation<\/abbr>\u2014H<sup>+<\/sup>\u2014and will differ only by the anion. Thus, we merely need to learn the relationship between the anion name and the acid name.<\/p>\n<h3>Binary Acids<\/h3>\n<p><abbr title=\"An acid that contains only hydrogen and one other element\">Binary acids<\/abbr> all have anions whose names end with \u2013ide. For example, the binary acid HCl is made from the chloride ion, Cl<sup>1\u2212<\/sup>. Its formula is written like that of any other ionic compound. We need one H<sup>+<\/sup> ion and one Cl<sup>1\u2212<\/sup> ion for the charges to add up to zero.<\/p>\n<p>We name the acid by using the following pattern. We must drop the \u2013ide ending from the anion name, in this case turning chloride into chlor. We take the root that remains (chlor), place the prefix hydro in front of it, the suffix \u2013ic after it, and the word acid at the end. In this way, the name chloride turns into hydrochloric acid.<\/p>\n<p>We can reverse this process to determine the formula of a binary acid if given the name. Hydroiodic acid displays the hydro-_____-ic acid pattern of a binary acid; therefore, its anion name must end with \u2013ide. From this, we realize that the ions involved are hydrogen (H<sup>+<\/sup>) and iodide (I<sup>1\u2212<\/sup>), so the formula must be HI.<\/p>\n<p>It is worth mentioning that there is one acid which is not binary but still follows this pattern. HCN contains three different elements, but the anion name is cyanide; therefore, the acid name is hydrocyanic acid.<\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following is the correct name for HBr?<\/p>\n<ol>\n<li>Bromic acid<\/li>\n<li>Bromidic acid<\/li>\n<li>Hydrobromous acid<\/li>\n<li>Hydrobromic acid<\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct answer is D. Neither choice A nor B uses the prefix hydro. Choice C has an incorrect suffix (\u2013ous rather than \u2013ic). Only choice D has the correct prefix\/suffix combination.<\/p>\n<\/section>\n<h3>Oxyacids<\/h3>\n<p>Since polyatomic ions frequently contain an atom combined with one or more oxygen atoms, acids made from these ions are often called oxyacids. Another reason for this name is that the acidic hydrogen is often bonded to an oxygen atom. The figure to the right shows the structure of perchloric acid, HClO<sub>4<\/sub>, which is a typical oxyacid.<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/chemistry\/wp-content\/uploads\/sites\/3\/2017\/08\/acidsOxides3.Perchloric-acid.png\" \/><\/center>As with binary acids, the naming of oxyacids is entirely dependent upon the name of the anion in the acid. Polyatomic ions almost always end with \u2013ite or \u2013ate. An \u2013ite ending is replaced with \u2013ous acid. An \u2013ate ending is replaced with \u2013ic acid.<\/p>\n<p>For example, HNO<sub>2 <\/sub>is made from hydrogen ion and the nitrite ion, NO<sub>2<\/sub><sup>1\u2212<\/sup>. Following the rule above turns nitrite into nitrous acid. Now consider the oxyacid of nitrogen that has one additional oxygen atom, HNO<sub>3<\/sub>. It is made from hydrogen ion and the nitrate ion. Using the rule above turns nitrate into nitric acid.<\/p>\n<p>Remember that some polyatomic ions have a prefix of hypo or per. These prefixes are not affected by the rules we have just learned. For example, HClO is made from a hydrogen ion and the hypochlorite ion, ClO<sup>1\u2212<\/sup>. We still simply change \u2013ite to \u2013ous acid, which yields the name hypochlorous acid. The prefix hypo is retained in the name.<\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following correctly names the anion present in iodic acid?<\/p>\n<ol>\n<li>Iodide<\/li>\n<li>Iodite<\/li>\n<li>Iodate<\/li>\n<li>Iodine<\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct answer is C. An ending of \u201c-ic acid\u201d (without a prefix of \u201chydro\u201d) means that the anion ends with \u201c-ate.\u201d The acid formed from choice A would be hydroiodic acid and from choice B would be iodous acid. Choice D is not an anion at all, so it cannot form an acid as such.<\/p>\n<\/section>\n<h3>Metal Oxides<\/h3>\n<p>You may recall that metals bond with nonmetals ionically &#8212; that is, they transfer one or more electrons from the metal to the nonmetal, creating charged particles that are electrostatically attracted to each other. Because oxygen is a nonmetal, it follows logically that metal oxides are ionic compounds.<\/p>\n<p>The oxide ion, O<sup>2\u2212<\/sup>, behaves as a relatively strong Bronsted-Lowry base by removing a hydrogen ion from a water molecule. When this occurs, the products are two hydroxide ions, OH<sup>1\u2212<\/sup> as seen in the Lewis structures below.<\/p>\n<p><center><img decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/chemistry\/wp-content\/uploads\/sites\/3\/2017\/08\/acidsOxides5.oxidewater.png\" \/><\/center>It is because of the formation of hydroxide ions that metal oxides are considered to be basic in nature. Sodium oxide, for example, will react with water to form sodium hydroxide according to the reaction: Na<sub>2<\/sub>O + H<sub>2<\/sub>O \u2192 2 NaOH.<\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following correctly shows the product formed when calcium oxide reacts with water?<\/p>\n<ol>\n<li>CaOH<\/li>\n<li>CaO\u00b7H<sub>2<\/sub>O<\/li>\n<li>H<sub>2<\/sub>CaO<sub>2<\/sub><\/li>\n<li>Ca(OH)<sub>2<\/sub><\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct answer is D. The oxide ion will combine with water to form hydroxide ion, ruling out choices B and C. Since calcium forms 2+ ions and hydroxide ions are 1\u2212, there must be two hydroxide ions for every one calcium ion, as in choice D.<\/p>\n<\/section>\n<h3>Nonmetal Oxides<\/h3>\n<p>When oxygen bonds with a nonmetal, it does so covalently, therefore the compound does not contain oxide ions. That\u2019s why adding water does not form hydroxide ions. Instead, the oxygen atom tends to bond with the other nonmetal in the compound, while the hydrogen atoms bond to the oxygen atoms. This is precisely the structure of an oxyacid, as discussed earlier.<\/p>\n<p>Since the hydrogen atoms are not reduced to hydrogen gas (H<sub>2<\/sub>) and the oxygen atoms are not oxidized to oxygen gas (O<sub>2<\/sub>), the nonmetal originally bonded to the oxygen must retain its original oxidation number. For example, in the reaction below, dichlorine monoxide (Cl<sub>2<\/sub>O) reacts with water to form hypochlorous acid. The oxidation number of chlorine is +1 in both compounds.<\/p>\n<p class=\"center\">Cl<sub>2<\/sub>O + H<sub>2<\/sub>O \u2192 2HClO<\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following correctly shows the product formed when SO<sub>2<\/sub> reacts with water?<\/p>\n<ol>\n<li>H<sub>2<\/sub>SO<sub>2<\/sub><\/li>\n<li>H<sub>2<\/sub>SO<sub>3<\/sub><\/li>\n<li>H<sub>2<\/sub>SO<sub>4<\/sub><\/li>\n<li>S(OH)<sub>2<\/sub><\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct answer is B. SO<sub>2<\/sub> is a nonmetal oxide, so it will form an acid, ruling out choice D. The oxidation number of sulfur in SO<sub>2<\/sub> is +4, which is the same as its oxidation number in H<sub>2<\/sub>SO<sub>3<\/sub>. Choices A and C are incorrect as the oxidation numbers for sulfur are +2 and +6, respectively.<\/p>\n<\/section>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following correctly shows the product formed when dinitrogen pentoxide, N<sub>2<\/sub>O<sub>5<\/sub>, reacts with water?<\/p>\n<ol>\n<li>NH<sub>3<\/sub><\/li>\n<li>HNO<sub>2<\/sub><\/li>\n<li>HNO<sub>3 <\/sub><\/li>\n<li>N(OH)<sub>3 <\/sub><\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">Choice C is correct. N<sub>2<\/sub>O<sub>5<\/sub> is a nonmetal oxide, so it will form an oxyacid with water, ruling out choices A and D. The oxidation numbers of nitrogen in choices B and C are +3 and + 5, respectively. Only choice C matches the oxidation number of nitrogen in N<sub>2<\/sub>O<sub>5<\/sub>.<\/p>\n<\/section>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following correctly shows the product formed when potassium oxide, K<sub>2<\/sub>O, reacts with water?<\/p>\n<ol>\n<li>KOH<\/li>\n<li>K(OH)<sub>2<\/sub><\/li>\n<li>HKO<\/li>\n<li>H<sub>3<\/sub>KO<sub>2<\/sub><\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">Choice A is correct. Metal oxides react with water to form metal hydroxides, eliminating choices C and D. Choice B does not have charges that add up to zero, so its formula is incorrect..<\/p>\n<\/section>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following correctly shows the product formed when tetraphosphorus decoxide, P<sub>4<\/sub>O<sub>10<\/sub>, reacts with water?<\/p>\n<ol>\n<li>HPO<sub>3<\/sub><\/li>\n<li>H<sub>3<\/sub>PO<sub>3 <\/sub><\/li>\n<li>HPO<sub>4 <\/sub><\/li>\n<li>H<sub>3<\/sub>PO<sub>4 <\/sub><\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">Choice D is correct. The nonmetal oxide reacts with water to form an oxyacid. The oxidation number of phosphorus in the oxyacid must be the same as its oxidation number in the original oxide, +5. Only choice D has a ratio of ions whose charges add up to zero and has an oxidation number for phosphorus of +5.<\/p>\n<\/section>\n<\/section>\n<p><!-- CONTENT ENDS HERE --><\/p>\n<p><!-- UPDATE NEXT\/PREVIOUS BELOW --><\/p>\n<div class=\"advance\">\n<p><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/writing-names-and-formulas\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/chemical-naming-and-structure\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/percent-composition-and-formulas\">Next Lesson \u27a1<\/a><\/p>\n<\/div>\n<p><a class=\"backtotop\" href=\"#title\">Back to Top<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u2b05 Previous Lesson\u00a0Workshop Index\u00a0Next Lesson \u27a1 Acids and Oxides Objective In this lesson we will review chemical names and formulas for acids. We will also review the acid\/base properties of oxides. Previously we covered&#8230; Oxidation numbers may be used in situations when true charges may not apply Oxidation numbers may be assigned using the following [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-248","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/248","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/comments?post=248"}],"version-history":[{"count":12,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/248\/revisions"}],"predecessor-version":[{"id":881,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/248\/revisions\/881"}],"wp:attachment":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/media?parent=248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}