{"id":256014,"date":"2025-07-13T17:01:29","date_gmt":"2025-07-13T17:01:29","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=256014"},"modified":"2025-07-13T17:01:32","modified_gmt":"2025-07-13T17:01:32","slug":"use-the-data-provided-below-to-calculate-the-lattice-energy-of-rbcl-2","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/13\/use-the-data-provided-below-to-calculate-the-lattice-energy-of-rbcl-2\/","title":{"rendered":"Use the data provided below to calculate the lattice energy of RbCl."},"content":{"rendered":"\n

Use the data provided below to calculate the lattice energy of RbCl. Is this value greater or less than the lattice energy of NaCl? Explain. Electron affinity of Cl = -349 kJ\/mol 1st ionization energy of Rb = 403 kJ\/mol Bond energy of Cl2 = 242 kJ\/mol Sublimation energy of Rb = 86.5 kJ\/mol \u00ce\u201dH\u00c2\u00b0[RbCl (s)] = -430.5 kJ\/mol Rb (s) + 1\/2 Cl2 (g) \u00e2\u2020\u2019 RbCl (s) This equation can be written as the sum of the following: Rb (s) \u00e2\u2020\u2019 Rb (g) sublimation \u00ce\u201dH\u00c2\u00b0 = +86.5 kJ\/mol Rb (g) \u00e2\u2020\u2019 Rb+ + e- 1st ionization energy \u00ce\u201dH\u00c2\u00b0 = +403 kJ\/mol Cl2 (g) \u00e2\u2020\u2019 2 Cl bond energy of Cl2 \u00ce\u201dH\u00c2\u00b0 = +242 kJ\/mol Cl + e- \u00e2\u2020\u2019 Cl- electron affinity of Cl \u00ce\u201dH\u00c2\u00b0 = -349 kJ\/mol Rb+ + Cl- \u00e2\u2020\u2019 RbCl lattice energy \u00ce\u201dH\u00c2\u00b0 = -222 kJ\/mol \u00ce\u201dH\u00c2\u00b0 = \u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0 Lattice energy \u00ce\u201dH\u00c2\u00b0 = \u00ce\u201dH\u00c2\u00b0 – (\u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0 + \u00ce\u201dH\u00c2\u00b0) = -430.5 – (86.5 + 403 + 242 – 349) = -692 kJ<\/p>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

To calculate the lattice energy of RbCl, we can use the provided data and apply the Born-Haber cycle, which is a series of steps that break down the formation of an ionic compound from its elements in their standard states.<\/p>\n\n\n\n

Step-by-Step Calculation:<\/h3>\n\n\n\n
    \n
  1. Sublimation of Rb(s)<\/strong>: This step involves converting solid rubidium (Rb) to gaseous rubidium atoms.\n
      \n
    • Sublimation energy of Rb<\/strong>: +86.5 kJ\/mol<\/li>\n<\/ul>\n<\/li>\n\n\n\n
    • Ionization of Rb(g)<\/strong>: The next step is the ionization of gaseous rubidium, which means it loses an electron to form Rb\u207a.\n
        \n
      • First ionization energy of Rb<\/strong>: +403 kJ\/mol<\/li>\n<\/ul>\n<\/li>\n\n\n\n
      • Dissociation of Cl\u2082(g)<\/strong>: Chlorine (Cl\u2082) is broken into two chlorine atoms (Cl) in the gas phase.\n
          \n
        • Bond energy of Cl\u2082<\/strong>: +242 kJ\/mol (for one mole of Cl\u2082 molecules, we get two moles of chlorine atoms)<\/li>\n<\/ul>\n<\/li>\n\n\n\n
        • Electron affinity of Cl<\/strong>: Chlorine atoms gain an electron to form chloride ions (Cl\u207b).\n
            \n
          • Electron affinity of Cl<\/strong>: -349 kJ\/mol<\/li>\n<\/ul>\n<\/li>\n\n\n\n
          • Formation of RbCl(s)<\/strong>: Finally, the Rb\u207a and Cl\u207b ions come together to form solid RbCl. This is the lattice energy, which we need to calculate.<\/li>\n<\/ol>\n\n\n\n

            The enthalpy of formation (\u0394H\u00b0) of RbCl (s)<\/strong> is given as:<\/p>\n\n\n\n

              \n
            • \u0394H\u00b0[RbCl (s)]<\/strong> = -430.5 kJ\/mol<\/li>\n<\/ul>\n\n\n\n

              Applying the Born-Haber Cycle:<\/h3>\n\n\n\n

              The enthalpy change for the formation of RbCl(s) is the sum of the steps: \u0394H=Sublimation energy of Rb+Ionization energy of Rb+12Bond energy of Cl\u2082+Electron affinity of Cl+Lattice energy\\Delta H = \\text{Sublimation energy of Rb} + \\text{Ionization energy of Rb} + \\frac{1}{2} \\text{Bond energy of Cl\u2082} + \\text{Electron affinity of Cl} + \\text{Lattice energy}\u0394H=Sublimation energy of Rb+Ionization energy of Rb+21\u200bBond energy of Cl\u2082+Electron affinity of Cl+Lattice energy<\/p>\n\n\n\n

              Substitute the known values: \u2212430.5=86.5+403+12(242)+(\u2212349)+Lattice energy-430.5 = 86.5 + 403 + \\frac{1}{2}(242) + (-349) + \\text{Lattice energy}\u2212430.5=86.5+403+21\u200b(242)+(\u2212349)+Lattice energy \u2212430.5=86.5+403+121\u2212349+Lattice energy-430.5 = 86.5 + 403 + 121 – 349 + \\text{Lattice energy}\u2212430.5=86.5+403+121\u2212349+Lattice energy \u2212430.5=261.5+Lattice energy-430.5 = 261.5 + \\text{Lattice energy}\u2212430.5=261.5+Lattice energy<\/p>\n\n\n\n

              Solving for lattice energy: Lattice energy=\u2212430.5\u2212261.5=\u2212692kJ\/mol\\text{Lattice energy} = -430.5 – 261.5 = -692 kJ\/molLattice energy=\u2212430.5\u2212261.5=\u2212692kJ\/mol<\/p>\n\n\n\n

              Conclusion:<\/h3>\n\n\n\n

              The lattice energy of RbCl is -692 kJ\/mol<\/strong>.<\/p>\n\n\n\n

              Comparison with NaCl:<\/h3>\n\n\n\n

              The lattice energy of NaCl is greater than that of RbCl. This is because NaCl forms from smaller Na\u207a and Cl\u207b ions compared to RbCl, leading to stronger electrostatic attraction between the ions in NaCl. Smaller ions allow the ions to be packed more closely, increasing the lattice energy. In contrast, Rb\u207a is larger than Na\u207a, which results in a lower lattice energy for RbCl. Therefore, the lattice energy of RbCl is less than<\/strong> the lattice energy of NaCl.<\/p>\n\n\n\n

              \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

              Use the data provided below to calculate the lattice energy of RbCl. Is this value greater or less than the lattice energy of NaCl? Explain. Electron affinity of Cl = -349 kJ\/mol 1st ionization energy of Rb = 403 kJ\/mol Bond energy of Cl2 = 242 kJ\/mol Sublimation energy of Rb = 86.5 kJ\/mol \u00ce\u201dH\u00c2\u00b0[RbCl […]<\/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-256014","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256014","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=256014"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256014\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=256014"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=256014"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=256014"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}