{"id":217999,"date":"2025-05-23T05:40:40","date_gmt":"2025-05-23T05:40:40","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=217999"},"modified":"2025-05-23T05:40:42","modified_gmt":"2025-05-23T05:40:42","slug":"what-is-the-molecular-mass-of-br2-a-79-90-amu-b-79-90-g-c-159-8-amu-d-159-8-g-e-2-65-x-10-22-amu-2","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/23\/what-is-the-molecular-mass-of-br2-a-79-90-amu-b-79-90-g-c-159-8-amu-d-159-8-g-e-2-65-x-10-22-amu-2\/","title":{"rendered":"What Is The Molecular Mass Of Br2 ? A) 79.90 Amu B) 79.90 G C) 159.8 Amu D) 159.8 G E) 2.65 X 10-22 Amu 2."},"content":{"rendered":"\n

What Is The Molecular Mass Of Br2 ? A) 79.90 Amu B) 79.90 G C) 159.8 Amu D) 159.8 G E) 2.65 X 10-22 Amu 2. What Is The Mass Of 4.50 X 1022 Cu Atoms? A) 7.47 X 10-2g B) 7.47 X 10-2 Amu C) 4.75 G D) 63.55 Amu E) 63.55 G 3.Determine The Number Of Moles Of Aluminum In 96.7 G Of Al. A) 0.279 Mol B) 3.58 Mol C) 7.43 Mol D) 4.21 Mol E) 6.02 X 1023 Mol 4.How Many<\/p>\n\n\n\n

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

Here are the correct answers and detailed explanations for each of the chemistry questions you’ve asked:<\/p>\n\n\n\n

\n\n\n\n

1. What is the molecular mass of Br\u2082?<\/strong><\/h3>\n\n\n\n

Correct Answer: C) 159.8 amu<\/strong><\/p>\n\n\n\n

Explanation:<\/strong><\/p>\n\n\n\n

The molecular mass (also called molecular weight) is the sum of the atomic masses of all atoms in a molecule.<\/p>\n\n\n\n

    \n
  • Bromine (Br) has an atomic mass of approximately 79.90 atomic mass units (amu)<\/strong>.<\/li>\n\n\n\n
  • Br\u2082 is a diatomic molecule<\/strong>, meaning it consists of two bromine atoms<\/strong> bonded together.<\/li>\n<\/ul>\n\n\n\n

    So, the molecular mass of Br\u2082 is:<\/p>\n\n\n\n

    $$
    79.90 \\, \\text{amu} \\times 2 = 159.8 \\, \\text{amu}
    $$<\/p>\n\n\n\n

    Let\u2019s analyze the other options:<\/p>\n\n\n\n

      \n
    • A) 79.90 amu<\/strong> is the atomic mass of one<\/strong> Br atom, not Br\u2082.<\/li>\n\n\n\n
    • B) 79.90 g<\/strong> and D) 159.8 g<\/strong> are values that might represent molar masses<\/strong> (mass per mole), not molecular masses.<\/li>\n\n\n\n
    • E) 2.65 x 10\u207b\u00b2\u00b2 amu<\/strong> is nonsensical in this context \u2014 that’s far too small.<\/li>\n<\/ul>\n\n\n\n

      The key idea is that molecular mass is always expressed in amu<\/strong>, not grams. Grams relate to the mass of moles, not individual molecules.<\/p>\n\n\n\n

      \n\n\n\n

      2. What is the mass of 4.50 \u00d7 10\u00b2\u00b2 Cu atoms?<\/strong><\/h3>\n\n\n\n

      Correct Answer: A) 7.47 \u00d7 10\u207b\u00b2 g<\/strong><\/p>\n\n\n\n

      Explanation:<\/strong><\/p>\n\n\n\n

      To find the mass of a number of atoms, use this formula:<\/p>\n\n\n\n

      $$
      \\text{Mass} = \\left( \\frac{\\text{Number of atoms}}{\\text{Avogadro’s number}} \\right) \\times \\text{Molar mass}
      $$<\/p>\n\n\n\n

      Where:<\/p>\n\n\n\n

        \n
      • Number of atoms = $4.50 \\times 10^{22}$<\/li>\n\n\n\n
      • Avogadro\u2019s number = $6.022 \\times 10^{23} \\, \\text{atoms\/mol}$<\/li>\n\n\n\n
      • Molar mass of Cu = 63.55 g\/mol<\/li>\n<\/ul>\n\n\n\n

        $$
        \\text{Mass} = \\left( \\frac{4.50 \\times 10^{22}}{6.022 \\times 10^{23}} \\right) \\times 63.55
        \\approx 0.0747 \\, \\text{g} = 7.47 \\times 10^{-2} \\, \\text{g}
        $$<\/p>\n\n\n\n

        This confirms option A<\/strong> is correct.<\/p>\n\n\n\n

        \n\n\n\n

        3. Determine the number of moles of aluminum in 96.7 g of Al.<\/strong><\/h3>\n\n\n\n

        Correct Answer: B) 3.58 mol<\/strong><\/p>\n\n\n\n

        Explanation:<\/strong><\/p>\n\n\n\n

        To find the number of moles:<\/p>\n\n\n\n

        $$
        \\text{Moles} = \\frac{\\text{Mass (g)}}{\\text{Molar mass (g\/mol)}}
        $$<\/p>\n\n\n\n

          \n
        • Mass = 96.7 g<\/li>\n\n\n\n
        • Molar mass of aluminum (Al) \u2248 26.98 g\/mol<\/li>\n<\/ul>\n\n\n\n

          $$
          \\text{Moles} = \\frac{96.7}{26.98} \\approx 3.58 \\, \\text{mol}
          $$<\/p>\n\n\n\n

          Thus, 3.58 mol<\/strong> is correct (Option B<\/strong>).<\/p>\n\n\n\n

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

          What Is The Molecular Mass Of Br2 ? A) 79.90 Amu B) 79.90 G C) 159.8 Amu D) 159.8 G E) 2.65 X 10-22 Amu 2. What Is The Mass Of 4.50 X 1022 Cu Atoms? A) 7.47 X 10-2g B) 7.47 X 10-2 Amu C) 4.75 G D) 63.55 Amu E) 63.55 G 3.Determine […]<\/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-217999","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/217999","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=217999"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/217999\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=217999"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=217999"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=217999"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}