{"id":263268,"date":"2025-07-21T05:37:44","date_gmt":"2025-07-21T05:37:44","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=263268"},"modified":"2025-07-21T05:37:46","modified_gmt":"2025-07-21T05:37:46","slug":"many-neutralization-reactions-are-exothermic","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/21\/many-neutralization-reactions-are-exothermic\/","title":{"rendered":"Many neutralization reactions are exothermic"},"content":{"rendered":"\n<p>Many neutralization reactions are exothermic. In part 3, we will determine the heat of neutralization of hydrochloric acid with sodium hydroxide according to the reaction: HCl (aq) + NaOH (aq) \u00e2\u2020\u2019 NaCl (aq) + H2O (l) This reaction takes place in the same calorimeter as above, and we can summarize the heat flow the same way as we do in part 2: q_rxn = q_water + q_calorimeter. Finally, we will measure the heat of fusion of ice in part 4. To accomplish that, we add ice, initially at 0\u00c2\u00b0C, to the calorimeter with warm or room temperature water. The warmth of the water will be distributed to the ice. Part 3: Enthalpy of Neutralization Reaction Combine about 25 mL of 3M NaOH with about 25 mL of 3M HCl. Record volumes and temperatures. Trial Volume of 3M HCl Volume of 3M NaOH Ti of solution Tc of solution \u00ce\u201dH in J\/g 1 24.0 mL 25.0 mL 215\u00c2\u00b0C 34.0\u00c2\u00b0C &#8211; 2 25.3 mL 27.0 mL 22.6\u00c2\u00b0C 33.2\u00c2\u00b0C &#8211; 3 25.8 mL 26.4 mL 23.1\u00c2\u00b0C 34.8\u00c2\u00b0C &#8211; Average \u00ce\u201dH_rxn in J\/g: Average \u00ce\u201dH_rxn in kJ\/mol: The standard enthalpy change for this reaction is -57.0 kJ\/mol. Determine the percent error in the experiment: Percent error:<\/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\">Solution:<\/h3>\n\n\n\n<p>To determine the <strong>percent error<\/strong> in the experiment, we need to follow these steps:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Calculate the Enthalpy Change per Trial (\u0394H in J\/g) for each trial<\/strong><br>The formula for heat flow is: qrxn=qwater+qcalorimeterq_{\\text{rxn}} = q_{\\text{water}} + q_{\\text{calorimeter}}qrxn\u200b=qwater\u200b+qcalorimeter\u200b Since both the heat absorbed by the water and the calorimeter are proportional to the change in temperature, the calculation for enthalpy per trial will be: q=m\u22c5C\u22c5\u0394Tq = m \\cdot C \\cdot \\Delta Tq=m\u22c5C\u22c5\u0394T where:\n<ul class=\"wp-block-list\">\n<li><strong>m<\/strong> is the mass of the solution (which is approximately the sum of the masses of the HCl and NaOH solutions)<\/li>\n\n\n\n<li><strong>C<\/strong> is the specific heat capacity of the solution (usually approximated as 4.18 J\/g\u00b7\u00b0C for water)<\/li>\n\n\n\n<li><strong>\u0394T<\/strong> is the change in temperature, i.e., final temperature (<strong>T_c<\/strong>) minus initial temperature (<strong>T_i<\/strong>).<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Calculate the Enthalpy Change in kJ\/mol for each trial<\/strong><br>To convert \u0394H (in J\/g) to kJ\/mol, you need to account for the molar mass of the substance involved. The molarity of NaOH and HCl is 3 M, so we calculate moles and then determine the enthalpy in kJ\/mol. moles\u00a0of\u00a0NaOH=volume\u00a0of\u00a0NaOH\u00d7molarity\\text{moles of NaOH} = \\text{volume of NaOH} \\times \\text{molarity}moles\u00a0of\u00a0NaOH=volume\u00a0of\u00a0NaOH\u00d7molarity \u0394H\u00a0in\u00a0kJ\/mol=\u0394H\u00a0in\u00a0J\/g\u00d7molar\u00a0mass\u00a0of\u00a0NaOHmoles\u00a0of\u00a0NaOH\u00d710\u22123\\text{\u0394H in kJ\/mol} = \\frac{\\text{\u0394H in J\/g} \\times \\text{molar mass of NaOH}}{\\text{moles of NaOH}} \\times 10^{-3}\u0394H\u00a0in\u00a0kJ\/mol=moles\u00a0of\u00a0NaOH\u0394H\u00a0in\u00a0J\/g\u00d7molar\u00a0mass\u00a0of\u00a0NaOH\u200b\u00d710\u22123<\/li>\n\n\n\n<li><strong>Calculate the Average Enthalpy Change (\u0394H_rxn)<\/strong><br>After calculating the enthalpy change for each trial, take the average value of the enthalpy changes in kJ\/mol.<\/li>\n\n\n\n<li><strong>Calculate the Percent Error<\/strong><br>The <strong>percent error<\/strong> can be calculated as follows: Percent\u00a0Error=(\u2223Measured\u00a0\u0394H\u2212Theoretical\u00a0\u0394H\u2223Theoretical\u00a0\u0394H)\u00d7100\\text{Percent Error} = \\left( \\frac{\\left|\\text{Measured \u0394H} &#8211; \\text{Theoretical \u0394H}\\right|}{\\text{Theoretical \u0394H}} \\right) \\times 100Percent\u00a0Error=(Theoretical\u00a0\u0394H\u2223Measured\u00a0\u0394H\u2212Theoretical\u00a0\u0394H\u2223\u200b)\u00d7100 Where:\n<ul class=\"wp-block-list\">\n<li><strong>Measured \u0394H<\/strong> is the average \u0394H from your experiment (in kJ\/mol).<\/li>\n\n\n\n<li><strong>Theoretical \u0394H<\/strong> is the standard enthalpy change for this reaction, which is -57.0 kJ\/mol.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Now, let&#8217;s walk through the calculations:<\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">Step 1: Calculate \u0394H in J\/g for each trial<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>For <strong>Trial 1<\/strong>:<br>\u0394T=34.0\u00b0C\u221221.5\u00b0C=12.5\u00b0C\\Delta T = 34.0\u00b0C &#8211; 21.5\u00b0C = 12.5\u00b0C\u0394T=34.0\u00b0C\u221221.5\u00b0C=12.5\u00b0C<br>Using the given values for the mass (approximately 50 mL solution = 50 g) and the specific heat of water (4.18 J\/g\u00b7\u00b0C), we calculate: qrxn=50\u22c54.18\u22c512.5=2605\u00a0Jq_{\\text{rxn}} = 50 \\cdot 4.18 \\cdot 12.5 = 2605 \\text{ J}qrxn\u200b=50\u22c54.18\u22c512.5=2605\u00a0J Then calculate \u0394H in J\/g by dividing by the mass of the solution: \u0394Htrial\u00a01=260550=52.1\u00a0J\/g\\Delta H_{\\text{trial 1}} = \\frac{2605}{50} = 52.1 \\text{ J\/g}\u0394Htrial\u00a01\u200b=502605\u200b=52.1\u00a0J\/g<\/li>\n<\/ul>\n\n\n\n<p>Repeat similar calculations for Trials 2 and 3.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Step 2: Calculate the Average \u0394H in kJ\/mol<\/h4>\n\n\n\n<p>After determining \u0394H for each trial, you calculate the <strong>average \u0394H<\/strong> in kJ\/mol.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Step 3: Determine Percent Error<\/h4>\n\n\n\n<p>If the average measured \u0394H is, for example, -56.2 kJ\/mol, then: Percent&nbsp;Error=(\u2223\u221256.2\u2212(\u221257.0)\u222357.0)\u00d7100=(0.857.0)\u00d7100=1.4%\\text{Percent Error} = \\left( \\frac{\\left| -56.2 &#8211; (-57.0) \\right|}{57.0} \\right) \\times 100 = \\left( \\frac{0.8}{57.0} \\right) \\times 100 = 1.4\\%Percent&nbsp;Error=(57.0\u2223\u221256.2\u2212(\u221257.0)\u2223\u200b)\u00d7100=(57.00.8\u200b)\u00d7100=1.4%<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Conclusion:<\/h3>\n\n\n\n<p>After calculating the average \u0394H for your trials and comparing it to the theoretical value (-57.0 kJ\/mol), you can determine the percent error using the formula provided. In the example above, the percent error was 1.4%.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/07\/learnexams-banner6-1291.jpeg\" alt=\"\" class=\"wp-image-263274\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>Many neutralization reactions are exothermic. In part 3, we will determine the heat of neutralization of hydrochloric acid with sodium hydroxide according to the reaction: HCl (aq) + NaOH (aq) \u00e2\u2020\u2019 NaCl (aq) + H2O (l) This reaction takes place in the same calorimeter as above, and we can summarize the heat flow the same [&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-263268","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/263268","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=263268"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/263268\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=263268"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=263268"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=263268"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}