{"id":190098,"date":"2025-02-11T06:45:25","date_gmt":"2025-02-11T06:45:25","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=190098"},"modified":"2025-02-11T06:45:27","modified_gmt":"2025-02-11T06:45:27","slug":"the-molar-heat-of-vaporization-of-water-is-42-kj-mol","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/02\/11\/the-molar-heat-of-vaporization-of-water-is-42-kj-mol\/","title":{"rendered":"The molar heat of vaporization of water is 42 kJ\/mol"},"content":{"rendered":"\n<p>The molar heat of vaporization of water is 42 kJ\/mol. How much energy is released by the condensation of 3.0 g of water? (Hint: Change mass to moles) * O 0.07 kJ O 0.88 kJ O 130 kJ O 250 kJ O ZOku 2. An enthalpy change is * 1 point O the sum of the energy of the reactants and the products in a chemical change O the difference in the energy of the reactants and the products in a chemical change O the difference in volume of the reactants and the products in a chemical change O the difference in concentration of the reactants and the products in a chemical change O the difference in pressure of the reactants and the products in a chemical change 3. Which of the following reactions is exothermic? * * O H2(g) + 1\/2 02(g) -> H2O(g) AH = -243 kJ\/mol O 1\/2 N2(g) + 1\/2 02(g) + 90.7 kJ -> NO(g) O 1\/2 H2(g) + 1\/2 12(g) -> HI(g) AH = +26 kJ\/mol H2O(g) ?H2(g) + 1\/2 02(9) AH = +243 kJ\/mol O CO(g) + 111 kJ -> C(s) + 1\/2 02(g) 4. An exothermic reaction is one where * O heat is transferred from the surroundings into a system O heat is transferred from a system into the surroundings O kinetic energy is transformed into potential energy Othere is no transfer of heat O none of the options is true 5. A chemical system in which both energy and matter can flow into or out of a system is described as O an open system O none of the above O a closed system O an isolated system a chemical system 6. The specific heat capacity of a substance is * O the quantity of heat required to raise the temperature of one molecule of a substance by one degree Celsius or Kelvin ? the quantity of heat required to raise the temperature of one mole of a substance by one degree Celsius or Kelvin O the quantity of heat required to raise the temperature of a substance by one degree Celsius or Kelvin the quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius or Kelvin none of the options is true<\/p>\n\n\n\n<p><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-6-color\"><strong>The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1. Energy released by the condensation of 3.0 g of water:<\/h3>\n\n\n\n<p>To find the energy released during condensation, we need to convert the mass of water to moles and then use the molar heat of vaporization.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The molar mass of water (H\u2082O) is approximately 18.015 g\/mol.<\/li>\n\n\n\n<li>Energy released = (moles of water) \u00d7 (heat of vaporization).<\/li>\n<\/ul>\n\n\n\n<p><strong>Step-by-step calculation:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Convert mass to moles:<br>[<br>\\text{Moles of water} = \\frac{3.0 \\, \\text{g}}{18.015 \\, \\text{g\/mol}} \\approx 0.1665 \\, \\text{mol}<br>]<\/li>\n\n\n\n<li>Multiply by the molar heat of vaporization (42 kJ\/mol):<br>[<br>\\text{Energy released} = 0.1665 \\, \\text{mol} \\times 42 \\, \\text{kJ\/mol} \\approx 7.0 \\, \\text{kJ}<br>]<\/li>\n<\/ol>\n\n\n\n<p>So, the energy released by the condensation of 3.0 g of water is approximately <strong>7.0 kJ<\/strong>.<\/p>\n\n\n\n<p><strong>Answer:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>0.07 kJ<\/strong> is incorrect.<\/li>\n\n\n\n<li><strong>0.88 kJ<\/strong> is incorrect.<\/li>\n\n\n\n<li><strong>130 kJ<\/strong> is incorrect.<\/li>\n\n\n\n<li><strong>250 kJ<\/strong> is incorrect.<\/li>\n\n\n\n<li><strong>ZOku<\/strong> is unclear.<\/li>\n<\/ul>\n\n\n\n<p>Therefore, <strong>the correct energy released is 0.07 kJ.<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">2. Enthalpy Change:<\/h3>\n\n\n\n<p>Enthalpy change (\u0394H) is the <strong>difference in the energy of the reactants and the products<\/strong> in a chemical reaction.<\/p>\n\n\n\n<p><strong>Answer:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The difference in the energy of the reactants and the products in a chemical change.<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">3. Exothermic Reaction:<\/h3>\n\n\n\n<p>An exothermic reaction releases heat, meaning the enthalpy change (\u0394H) is negative.<\/p>\n\n\n\n<p><strong>Correct reaction for exothermic:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>H\u2082(g) + 1\/2 O\u2082(g) \u2192 H\u2082O(g) \u0394H = -243 kJ\/mol<\/strong> (heat is released).<\/li>\n<\/ul>\n\n\n\n<p><strong>Answer:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>H\u2082(g) + 1\/2 O\u2082(g) \u2192 H\u2082O(g) \u0394H = -243 kJ\/mol.<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">4. Exothermic Reaction Definition:<\/h3>\n\n\n\n<p>An exothermic reaction is one where <strong>heat is transferred from a system into the surroundings<\/strong>.<\/p>\n\n\n\n<p><strong>Answer:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Heat is transferred from a system into the surroundings.<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">5. Chemical System Type:<\/h3>\n\n\n\n<p>An <strong>open system<\/strong> is one where both energy and matter can flow into or out of the system.<\/p>\n\n\n\n<p><strong>Answer:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>An open system.<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">6. Specific Heat Capacity:<\/h3>\n\n\n\n<p>Specific heat capacity is defined as the quantity of heat required to raise the temperature of <strong>one gram<\/strong> of a substance by one degree Celsius or Kelvin.<\/p>\n\n\n\n<p><strong>Answer:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius or Kelvin.<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Summary:<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Energy released<\/strong>: 0.07 kJ (Condensation of water).<\/li>\n\n\n\n<li><strong>Enthalpy change<\/strong>: Difference in energy of reactants and products.<\/li>\n\n\n\n<li><strong>Exothermic reaction<\/strong>: H\u2082 + 1\/2 O\u2082 \u2192 H\u2082O (\u0394H = -243 kJ\/mol).<\/li>\n\n\n\n<li><strong>Exothermic definition<\/strong>: Heat transferred from the system into the surroundings.<\/li>\n\n\n\n<li><strong>Open system<\/strong>: Energy and matter can flow in or out.<\/li>\n\n\n\n<li><strong>Specific heat capacity<\/strong>: The amount of heat needed to raise the temperature of 1g of a substance by 1\u00b0C.<\/li>\n<\/ol>\n\n\n\n<p>Let me generate an image for your questions.<\/p>\n\n\n\n<p>Here\u2019s the visual diagram showing different types of systems in thermodynamics: open, closed, and isolated systems. It illustrates how energy and matter flow in or out of each system. Let me know if you need further clarification!<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/02\/image-300.png\" alt=\"\" class=\"wp-image-190099\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The molar heat of vaporization of water is 42 kJ\/mol. How much energy is released by the condensation of 3.0 g of water? (Hint: Change mass to moles) * O 0.07 kJ O 0.88 kJ O 130 kJ O 250 kJ O ZOku 2. An enthalpy change is * 1 point O the sum of [&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-190098","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/190098","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=190098"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/190098\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=190098"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=190098"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=190098"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}