{"id":221985,"date":"2025-05-30T19:00:24","date_gmt":"2025-05-30T19:00:24","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=221985"},"modified":"2025-05-30T19:00:27","modified_gmt":"2025-05-30T19:00:27","slug":"dipole-moments-and-a-gedanken-synthesis-1","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/30\/dipole-moments-and-a-gedanken-synthesis-1\/","title":{"rendered":"Dipole Moments and A Gedanken Synthesis 1"},"content":{"rendered":"\n<p>Part III. Dipole Moments and A Gedanken Synthesis 1. (1 point) Compare the dipole moment magnitudes of propane and 2-chloropropane. Why do they differ so drastically? 2. (1 point) Draw Newman projections of gauche-1,2-dichloroethane and anti-1,2-dichloroethane. Draw the individual bond-dipole arrows for each polar bond within each molecule. 3. (1 point) Compare the dipole moment magnitudes for gauche-1,2-dichloroethane and anti-1,2-dichloroethane. Why does one have a dipole moment, whereas the other does not? Refer to the orientation of the polar bonds within each conformer. 4. (1 point) Recall that gauche-1,2-dichloroethane and anti-1,2-dichloroethane are different conformations of the same molecule. Does the interconversion of these two occur readily at room temperature? 5. (1 point) Draw cis- and trans-1,2-dichloroethene. Draw the individual bond-dipole arrows for each polar bond within each molecule ( 2 bonds for each molecule).<\/p>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-1-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>1. Dipole Moment Comparison: Propane vs. 2-Chloropropane<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Propane<\/strong> has a <strong>dipole moment of ~0 D<\/strong> because it is a symmetrical, nonpolar molecule with only C\u2013C and C\u2013H bonds, which have nearly equal electronegativities.<\/li>\n\n\n\n<li><strong>2-Chloropropane<\/strong> has a <strong>significantly larger dipole moment (~2.05 D)<\/strong> because the C\u2013Cl bond is highly polar (Cl is much more electronegative than C or H), creating an asymmetrical electron distribution.<\/li>\n<\/ul>\n\n\n\n<p>The large difference arises because 2-chloropropane introduces a strongly electronegative chlorine atom that draws electron density toward itself, resulting in a permanent dipole. Propane lacks any such electronegative substituent.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>2. Newman Projections and Dipole Arrows<\/strong><\/h3>\n\n\n\n<p><strong>Gauche-1,2-dichloroethane<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>    Cl         H\n     \\       \/\n      C\u2014C\n     \/       \\\n    H         Cl\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Newman view<\/strong>: Front C \u2013 Cl and H; Back C \u2013 Cl and H<\/li>\n\n\n\n<li>Cl atoms are <strong>60\u00b0 apart<\/strong> (gauche).<\/li>\n<\/ul>\n\n\n\n<p><strong>Anti-1,2-dichloroethane<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>    Cl         H\n     \\       \/\n      C\u2014C\n     \/       \\\n    Cl        H\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Newman view<\/strong>: Front C \u2013 Cl; Back C \u2013 Cl<\/li>\n\n\n\n<li>Cl atoms are <strong>180\u00b0 apart<\/strong> (anti).<\/li>\n<\/ul>\n\n\n\n<p>Draw dipole arrows (<strong>\u2192<\/strong>) from C to Cl for each Cl bond.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>3. Dipole Moment: Gauche vs. Anti<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Gauche<\/strong>: The Cl\u2013C dipoles are not opposite and don&#8217;t cancel, so the molecule has a <strong>net dipole moment<\/strong>.<\/li>\n\n\n\n<li><strong>Anti<\/strong>: The Cl\u2013C dipoles are equal and opposite, so they <strong>cancel out<\/strong>, resulting in <strong>no net dipole moment<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p>Dipole cancellation depends on vector addition; in anti, the vectors are 180\u00b0 apart, canceling each other.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>4. Interconversion at Room Temperature<\/strong><\/h3>\n\n\n\n<p>Yes, <strong>gauche and anti conformers interconvert readily<\/strong> at room temperature via rotation around the C\u2013C sigma bond. This rotation requires very little energy and happens frequently at ambient conditions.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>5. Cis- and Trans-1,2-dichloroethene Structures &amp; Dipole Arrows<\/strong><\/h3>\n\n\n\n<p><strong>Cis-1,2-dichloroethene<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>     Cl       H\n      \\     \/\n       C = C\n      \/     \\\n     H       Cl\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Dipole arrows from each C to Cl both point <strong>upward<\/strong> \u2192 net dipole <strong>adds up<\/strong>.<\/li>\n<\/ul>\n\n\n\n<p><strong>Trans-1,2-dichloroethene<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>     Cl       H\n      \\     \/\n       C = C\n      \/     \\\n     Cl      H\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Dipole arrows from each C to Cl point in <strong>opposite directions<\/strong> \u2192 dipoles <strong>cancel<\/strong> \u2192 <strong>no net dipole<\/strong>.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/05\/learnexams-banner4-152.jpeg\" alt=\"\" class=\"wp-image-221986\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>Part III. Dipole Moments and A Gedanken Synthesis 1. (1 point) Compare the dipole moment magnitudes of propane and 2-chloropropane. Why do they differ so drastically? 2. (1 point) Draw Newman projections of gauche-1,2-dichloroethane and anti-1,2-dichloroethane. Draw the individual bond-dipole arrows for each polar bond within each molecule. 3. (1 point) Compare the dipole moment [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-221985","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/221985","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=221985"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/221985\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=221985"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=221985"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=221985"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}