{"id":385,"date":"2017-08-21T06:46:25","date_gmt":"2017-08-21T06:46:25","guid":{"rendered":"http:\/\/americanboard.org\/Subjects\/chemistry\/?page_id=385"},"modified":"2017-09-19T17:56:13","modified_gmt":"2017-09-19T17:56:13","slug":"the-mole","status":"publish","type":"page","link":"https:\/\/americanboard.org\/Subjects\/chemistry\/the-mole\/","title":{"rendered":"The Mole"},"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\/types-of-chemical-equations\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/reactions-and-reactivity\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/chemical-calculations-and-yields\">Next Lesson\u00a0\u27a1<\/a><\/p>\n<\/div>\n<p><!-- UPDATE NEXT\/PREVIOUS ABOVE --><\/p>\n<p><!-- CONTENT STARTS HERE --><\/p>\n<h1 id=\"title\">Reactions and Reactivity: The Mole<\/h1>\n<h4>Objective<\/h4>\n<p>In this lesson we will review the concept of the mole and how it is used to weigh and count atoms and molecules.<\/p>\n<h4>Previously we covered&#8230;<\/h4>\n<ul>\n<li>Equations for reactions occurring in aqueous solution can be written showing only the ions which react.<\/li>\n<li>Molecular equations include all of the compounds\u00a0and elements taking part in the reaction, including their physical\u00a0state\u2014solid, liquid, gas or aqueous.<\/li>\n<li>Ionic equations are written when solutions of ionic\u00a0compounds are involved in the reaction.<\/li>\n<li>Net ionic equations are used to show only the ions\u00a0which react to form products.<\/li>\n<li>Spectator ions are not shown in net ionic equations.<\/li>\n<\/ul>\n<section>\n<h3>The Mole<\/h3>\n<p>The concept of the mole is\u00a0ubiquitous in chemistry and is involved in virtually\u00a0all chemical calculations. The mole provides a way for\u00a0chemists to\u00a0count molecules by weighing (or massing) them. The mole is merely a very large number of items, or specifically 6.02 \u00d7 10<sup>23<\/sup> items, just as one dozen is 12 items.<\/p>\n<p>The concept of atomic mass\u00a0has previously been discussed\u00a0in terms of the mass of one atom having a mass in\u00a0<abbr title=\"Amu (atomic mass unit): A unit of mass equal to one-twelfth the mass of a carbon-12 atom\">atomic\u00a0mass\u00a0units<\/abbr> (amu)\u00a0equal to the average atomic weight found on the Periodic Table. Or the\u00a0mass of\u00a0a molecule is equal to the sum of the masses of the atoms contained in\u00a0the\u00a0molecule. The sum of the masses in grams of all of the subatomic\u00a0particles in a mole of any atom is remarkably close to the atomic mass shown on the\u00a0periodic\u00a0table for the element. (The small difference is due to the presence \u00a0of\u00a0isotopes\u00a0and the fact that a bound nucleus has a different mass than the unbound\u00a0mass of\u00a0the \u00a0articles\u2014but that we\u2019ll leave for yet another \u00a0lesson.)<\/p>\n<p>Say, for example, we took a\u00a0handful of paperclips and\u00a0measured its mass. Then we measured the mass of exactly one dozen paper\u00a0clips\u00a0(12), we would have a way to determine how many dozen paperclips were\u00a0in the\u00a0handful. Simply divide the mass of the handful by the mass of one\u00a0dozen. The\u00a0mass of one mole of atoms of an element or the mass of one mole of\u00a0molecules of\u00a0a compound is called the\u00a0<abbr title=\"Mass of one mole of a substance, in grams\">molar mass<\/abbr>. If a sample of\u00a0sodium chloride is\u00a0454 g, and the molar mass of sodium chloride is 58.5 g, dividing the\u00a0total mass\u00a0by the mass of one mole will give the number of moles of sodium\u00a0chloride in\u00a0that sample<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/chemistry\/wp-content\/uploads\/sites\/3\/2017\/08\/s3_001.gif\" width=\"184\" height=\"44\" \/><\/center>However, if given the same\u00a0mass of sugar, 454 g, with a\u00a0molar mass of 342 g, the number of moles in that sugar sample is 1.33.\u00a0Because\u00a0the sugar molecule is larger, it takes fewer moles to account for the\u00a0same mass\u00a0as the salt. If\u00a0the number of moles of a substance is known, the\u00a0number of grams present can be determined by multiplying the number of\u00a0moles by\u00a0the molar mass. If we are told that we need 0.0400 moles of sugar in a\u00a0solution, we need to measure that amount using a balance. Balances,\u00a0however,\u00a0measure in grams.<\/p>\n<p>To determine the number of grams of sugar, we\u00a0multiply the\u00a0number of moles by the molar mass of the sugar.<\/p>\n<p><center><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/americanboard.org\/Subjects\/chemistry\/wp-content\/uploads\/sites\/3\/2017\/08\/s3_002.gif\" width=\"252\" height=\"26\" \/><\/center><\/p>\n<section class=\"question\">\n<h4>Question<\/h4>\n<p>Which of the following contains the largest number of molecules?<\/p>\n<ol>\n<li>500 g of H<sub>2<\/sub><\/li>\n<li>500 g of N<sub>2<\/sub><\/li>\n<li>500 g of O<sub>2<\/sub><\/li>\n<li>500 g of NH<sub>3<\/sub><\/li>\n<\/ol>\n<p><a class=\"button button-primary q-answer\"> Reveal Answer <\/a><\/p>\n<p class=\"q-reveal\">The correct\u00a0answer is A because H<sub>2<\/sub> has the smallest molar mass of the four compounds.\u00a0To obtain the number of moles, the mass is divided by the molar mass.\u00a0The smaller the molar mass, the greater the number of moles.<\/p>\n<\/section>\n<p><!-- CONTENT ENDS HERE --><\/p>\n<p><!-- UPDATE NEXT\/PREVIOUS BELOW --><\/p>\n<div class=\"advance\"><a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/types-of-chemical-equations\">\u2b05 Previous Lesson<\/a>\u00a0<a class=\"button\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/reactions-and-reactivity\">Workshop Index<\/a>\u00a0<a class=\"button button-primary\" href=\"http:\/\/americanboard.org\/Subjects\/chemistry\/chemical-calculations-and-yields\">Next Lesson\u00a0\u27a1<\/a><\/div>\n<p><a class=\"backtotop\" href=\"#title\">Back to Top<\/a><\/p>\n<\/section>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\u2b05 Previous Lesson\u00a0Workshop Index\u00a0Next Lesson\u00a0\u27a1 Reactions and Reactivity: The Mole Objective In this lesson we will review the concept of the mole and how it is used to weigh and count atoms and molecules. Previously we covered&#8230; Equations for reactions occurring in aqueous solution can be written showing only the ions which react. Molecular equations [&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-385","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/385","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=385"}],"version-history":[{"count":11,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/385\/revisions"}],"predecessor-version":[{"id":893,"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/pages\/385\/revisions\/893"}],"wp:attachment":[{"href":"https:\/\/americanboard.org\/Subjects\/chemistry\/wp-json\/wp\/v2\/media?parent=385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}