{"id":3233,"date":"2016-08-25T19:38:50","date_gmt":"2016-08-25T19:38:50","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/?post_type=chapter&#038;p=3233"},"modified":"2016-08-26T19:21:40","modified_gmt":"2016-08-26T19:21:40","slug":"reaction-intermediate","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/chapter\/reaction-intermediate\/","title":{"raw":"Reaction Intermediate","rendered":"Reaction Intermediate"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\n<div>\r\n<ul>\r\n \t<li>Define intermediate.<\/li>\r\n \t<li>Describe the role of intermediates in reaction mechanisms.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox examples\">\r\n<h3>Ozone depletetion<\/h3>\r\n[caption id=\"\" align=\"aligncenter\" width=\"400\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212905\/20140811155715891288.jpeg\" alt=\"The ozone radical is an intermediate that in the decomposition of ozone by ultraviolet radiation\" width=\"400\" height=\"354\" \/> Ozone waves. Courtesy of NASA\/<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Uars_ozone_waves.jpg\">Wikimedia<\/a>.[\/caption]\r\n\r\nOzone (O <sub> 3 <\/sub> ) depletion in the atmosphere is of significant concern. This gas serves as a protection against the ultraviolet rays of the sun. Ozone is naturally depleted in addition to the depletion caused by human-made chemicals. The depletion reaction is a two-step process:\r\n\r\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212907\/ba4181d7bbc878bf668be4f16ad10b60.png\" alt=\"&amp; text{O}_3 + text{ultraviolet light} rightarrow text{O}_2 + {text{O} cdot} (text{free radical}) text{slow reaction} \\&amp; {text{O} cdot} + text{O}_3 rightarrow 2 text{O}_2 text{fast reaction}\" width=\"465\" height=\"43\" \/>\r\n\r\nThe free radical is not a part of the overall equation, but can be detected in the lab.\r\n\r\n<\/div>\r\n<h2>Intermediate<\/h2>\r\nReaction mechanisms describe how the material in a chemical reaction gets from the initial reactants to the final products. One reaction that illustrates a reaction mechanism is the reaction between nitrogen monoxide and oxygen to form nitrogen dioxide:\r\n\r\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212908\/9fb73416fb025f021ed9ef66bf5b767f.png\" alt=\"2 text{NO}(g)+ text{O}_2(g) rightarrow 2 text{NO}_2(g)\" width=\"220\" height=\"18\" \/>\r\n\r\nIt may seem as though this reaction would occur as the result of a collision between two NO molecules with one O <sub> 2 <\/sub> molecule. However, careful analysis of the reaction has detected the presence of N <sub> 2 <\/sub> O <sub> 2 <\/sub> during the reaction. A proposed mechanism for the reaction consists of two elementary steps:\r\n\r\nStep 1: <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212909\/6dcc86c0c1dfa974f0e8d08565b9c41e.png\" alt=\"2 text{NO}(g) rightarrow text{N}_2 text{O}_2(g)\" width=\"152\" height=\"18\" \/>\r\n\r\nStep 2: <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212910\/2460af3c02e9f28ca53c99077f758b6d.png\" alt=\"text{N}_2 text{O}_2(g)+ text{O}_2(g) rightarrow 2 text{NO}_2(g)\" width=\"225\" height=\"18\" \/>\r\n\r\nIn the first step, two molecules of NO collide to form a molecule of N <sub> 2 <\/sub> O <sub> 2 <\/sub> . In the second step, that molecule of N <sub> 2 <\/sub> O <sub> 2 <\/sub> collides with a molecule of O <sub> 2 <\/sub> to produce two molecules of NO <sub> 2 <\/sub> . The overall chemical reaction is the sum of the two elementary steps:\r\n\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212911\/01950070626a958f5d602b9c23fe4e0c.png\" alt=\"&amp; qquad qquad 2 text{NO} (g) rightarrow cancel{text{N}_2 text{O}_2(g)} \\&amp; underline{;; cancel{text{N}_2text{O}_2(g)} + text{O}_2(g) rightarrow 2 text{NO}_2(g) ;;} \\&amp; 2 text{NO}(g)+ text{O}_2(g) rightarrow 2 text{NO}_2(g)\" width=\"247\" height=\"74\" \/>\r\n\r\nThe N <sub> 2 <\/sub> O <sub> 2 <\/sub> molecule is not part of the overall reaction. It was produced in the first elementary step, then reacts in the second elementary step. An <strong> intermediate <\/strong> is a species which appears in the mechanism of a reaction, but not in the overall balanced equation. An intermediate is always formed in an early step in the mechanism and consumed in a later step.\r\n<div>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"162\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212912\/20140811155715985080.jpeg\" alt=\"Caramel\/burnt orange colored liquid in a glass bottle on the left and yellow\/honey colored liquid in the right.\" width=\"162\" height=\"192\" longdesc=\"Nitrogen%20dioxide%20%28left%29%20and%20dinitrogen%20tetroxide%20%28right%29.\" \/> Figure 1. Nitrogen dioxide (left) and dinitrogen tetroxide (right). User:Greenhorn1\/<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:NO2-N2O4.jpg\">Wikipedia<\/a>.[\/caption]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Summary<\/h3>\r\n<ul>\r\n \t<li>The role of intermediates in reaction mechanisms is described.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Practice<\/h3>\r\nRead the material at the link below and answer the questions at the end:\r\n\r\n<a href=\"http:\/\/chemwiki.ucdavis.edu\/Physical_Chemistry\/Kinetics\/Rate_Laws\/Reaction_Mechanisms\/Reaction_Mechanisms\"> http:\/\/chemwiki.ucdavis.edu\/Physical_Chemistry\/Kinetics\/Rate_Laws\/Reaction_Mechanisms\/Reaction_Mechanisms<\/a>\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Review<\/h3>\r\n<ol>\r\n \t<li>What is the intermediate in the reaction described above?<\/li>\r\n \t<li>Do we see this intermediate in the actual reaction mix?<\/li>\r\n \t<li>Where do we first see an intermediate in a reaction mechanism?<\/li>\r\n \t<li>What happens to the intermediate?<\/li>\r\n<\/ol>\r\n<\/div>\r\n<h2>\u00a0Glossary<\/h2>\r\n<div>\r\n<ul>\r\n \t<li><strong> intermediate: <\/strong> A species which appears in the mechanism of a reaction, but not in the overall balanced equation.<\/li>\r\n<\/ul>\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<div>\n<ul>\n<li>Define intermediate.<\/li>\n<li>Describe the role of intermediates in reaction mechanisms.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox examples\">\n<h3>Ozone depletetion<\/h3>\n<div style=\"width: 410px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212905\/20140811155715891288.jpeg\" alt=\"The ozone radical is an intermediate that in the decomposition of ozone by ultraviolet radiation\" width=\"400\" height=\"354\" \/><\/p>\n<p class=\"wp-caption-text\">Ozone waves. Courtesy of NASA\/<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Uars_ozone_waves.jpg\">Wikimedia<\/a>.<\/p>\n<\/div>\n<p>Ozone (O <sub> 3 <\/sub> ) depletion in the atmosphere is of significant concern. This gas serves as a protection against the ultraviolet rays of the sun. Ozone is naturally depleted in addition to the depletion caused by human-made chemicals. The depletion reaction is a two-step process:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212907\/ba4181d7bbc878bf668be4f16ad10b60.png\" alt=\"&amp; text{O}_3 + text{ultraviolet light} rightarrow text{O}_2 + {text{O} cdot} (text{free radical}) text{slow reaction} \\&amp; {text{O} cdot} + text{O}_3 rightarrow 2 text{O}_2 text{fast reaction}\" width=\"465\" height=\"43\" \/><\/p>\n<p>The free radical is not a part of the overall equation, but can be detected in the lab.<\/p>\n<\/div>\n<h2>Intermediate<\/h2>\n<p>Reaction mechanisms describe how the material in a chemical reaction gets from the initial reactants to the final products. One reaction that illustrates a reaction mechanism is the reaction between nitrogen monoxide and oxygen to form nitrogen dioxide:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212908\/9fb73416fb025f021ed9ef66bf5b767f.png\" alt=\"2 text{NO}(g)+ text{O}_2(g) rightarrow 2 text{NO}_2(g)\" width=\"220\" height=\"18\" \/><\/p>\n<p>It may seem as though this reaction would occur as the result of a collision between two NO molecules with one O <sub> 2 <\/sub> molecule. However, careful analysis of the reaction has detected the presence of N <sub> 2 <\/sub> O <sub> 2 <\/sub> during the reaction. A proposed mechanism for the reaction consists of two elementary steps:<\/p>\n<p>Step 1: <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212909\/6dcc86c0c1dfa974f0e8d08565b9c41e.png\" alt=\"2 text{NO}(g) rightarrow text{N}_2 text{O}_2(g)\" width=\"152\" height=\"18\" \/><\/p>\n<p>Step 2: <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212910\/2460af3c02e9f28ca53c99077f758b6d.png\" alt=\"text{N}_2 text{O}_2(g)+ text{O}_2(g) rightarrow 2 text{NO}_2(g)\" width=\"225\" height=\"18\" \/><\/p>\n<p>In the first step, two molecules of NO collide to form a molecule of N <sub> 2 <\/sub> O <sub> 2 <\/sub> . In the second step, that molecule of N <sub> 2 <\/sub> O <sub> 2 <\/sub> collides with a molecule of O <sub> 2 <\/sub> to produce two molecules of NO <sub> 2 <\/sub> . The overall chemical reaction is the sum of the two elementary steps:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212911\/01950070626a958f5d602b9c23fe4e0c.png\" alt=\"&amp; qquad qquad 2 text{NO} (g) rightarrow cancel{text{N}_2 text{O}_2(g)} \\&amp; underline{;; cancel{text{N}_2text{O}_2(g)} + text{O}_2(g) rightarrow 2 text{NO}_2(g) ;;} \\&amp; 2 text{NO}(g)+ text{O}_2(g) rightarrow 2 text{NO}_2(g)\" width=\"247\" height=\"74\" \/><\/p>\n<p>The N <sub> 2 <\/sub> O <sub> 2 <\/sub> molecule is not part of the overall reaction. It was produced in the first elementary step, then reacts in the second elementary step. An <strong> intermediate <\/strong> is a species which appears in the mechanism of a reaction, but not in the overall balanced equation. An intermediate is always formed in an early step in the mechanism and consumed in a later step.<\/p>\n<div>\n<div style=\"width: 172px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/53\/2014\/08\/19212912\/20140811155715985080.jpeg\" alt=\"Caramel\/burnt orange colored liquid in a glass bottle on the left and yellow\/honey colored liquid in the right.\" width=\"162\" height=\"192\" longdesc=\"Nitrogen%20dioxide%20%28left%29%20and%20dinitrogen%20tetroxide%20%28right%29.\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 1. Nitrogen dioxide (left) and dinitrogen tetroxide (right). User:Greenhorn1\/<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:NO2-N2O4.jpg\">Wikipedia<\/a>.<\/p>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Summary<\/h3>\n<ul>\n<li>The role of intermediates in reaction mechanisms is described.<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Practice<\/h3>\n<p>Read the material at the link below and answer the questions at the end:<\/p>\n<p><a href=\"http:\/\/chemwiki.ucdavis.edu\/Physical_Chemistry\/Kinetics\/Rate_Laws\/Reaction_Mechanisms\/Reaction_Mechanisms\"> http:\/\/chemwiki.ucdavis.edu\/Physical_Chemistry\/Kinetics\/Rate_Laws\/Reaction_Mechanisms\/Reaction_Mechanisms<\/a><\/p>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Review<\/h3>\n<ol>\n<li>What is the intermediate in the reaction described above?<\/li>\n<li>Do we see this intermediate in the actual reaction mix?<\/li>\n<li>Where do we first see an intermediate in a reaction mechanism?<\/li>\n<li>What happens to the intermediate?<\/li>\n<\/ol>\n<\/div>\n<h2>\u00a0Glossary<\/h2>\n<div>\n<ul>\n<li><strong> intermediate: <\/strong> A species which appears in the mechanism of a reaction, but not in the overall balanced equation.<\/li>\n<\/ul>\n<\/div>\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-3233\">\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 Concepts Intermediate. <strong>Authored by<\/strong>: Calbreath, Baxter, et al.. <strong>Provided by<\/strong>: CK12.org. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.ck12.org\/book\/CK-12-Chemistry-Concepts-Intermediate\/\">http:\/\/www.ck12.org\/book\/CK-12-Chemistry-Concepts-Intermediate\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC: Attribution-NonCommercial<\/a><\/em><\/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":29,"menu_order":12,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Chemistry Concepts Intermediate\",\"author\":\"Calbreath, Baxter, et al.\",\"organization\":\"CK12.org\",\"url\":\"http:\/\/www.ck12.org\/book\/CK-12-Chemistry-Concepts-Intermediate\/\",\"project\":\"\",\"license\":\"cc-by-nc\",\"license_terms\":\"\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-3233","chapter","type-chapter","status-publish","hentry"],"part":2339,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/3233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/users\/29"}],"version-history":[{"count":4,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/3233\/revisions"}],"predecessor-version":[{"id":3438,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/3233\/revisions\/3438"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/parts\/2339"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapters\/3233\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/media?parent=3233"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/pressbooks\/v2\/chapter-type?post=3233"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/contributor?post=3233"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/umes-cheminter\/wp-json\/wp\/v2\/license?post=3233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}