{"id":270185,"date":"2025-07-25T05:19:34","date_gmt":"2025-07-25T05:19:34","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=270185"},"modified":"2025-07-25T05:19:36","modified_gmt":"2025-07-25T05:19:36","slug":"what-is-the-average-atomic-mass-of-potassium-given-the-following-values","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/25\/what-is-the-average-atomic-mass-of-potassium-given-the-following-values\/","title":{"rendered":"What is the average atomic mass of potassium given the following values"},"content":{"rendered":"\n<p>What is the average atomic mass of potassium given the following values? Isotope Abundance Atomic Mass Potassium-39 98.3% 38.96 amu Potassium-40 0.0100% 39.96 amu Potassium-41 6.69% 40.96 amu 38.5 amu 39.4 amu 41.0 amu 42.5 amu<\/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<p>To find the average atomic mass of potassium, we can use the weighted average formula. The formula to calculate the average atomic mass is:Average&nbsp;Atomic&nbsp;Mass=\u2211(Fractional&nbsp;Abundance\u00d7Atomic&nbsp;Mass)\\text{Average Atomic Mass} = \\sum (\\text{Fractional Abundance} \\times \\text{Atomic Mass})Average&nbsp;Atomic&nbsp;Mass=\u2211(Fractional&nbsp;Abundance\u00d7Atomic&nbsp;Mass)<\/p>\n\n\n\n<p>We are given the following data:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Potassium-39: Abundance = 98.3%, Atomic Mass = 38.96 amu<\/li>\n\n\n\n<li>Potassium-40: Abundance = 0.0100%, Atomic Mass = 39.96 amu<\/li>\n\n\n\n<li>Potassium-41: Abundance = 6.69%, Atomic Mass = 40.96 amu<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Step 1: Convert the percentage abundance to fractional form<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Potassium-39: 98.3%=0.98398.3\\% = 0.98398.3%=0.983<\/li>\n\n\n\n<li>Potassium-40: 0.0100%=0.0001000.0100\\% = 0.0001000.0100%=0.000100<\/li>\n\n\n\n<li>Potassium-41: 6.69%=0.06696.69\\% = 0.06696.69%=0.0669<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Step 2: Multiply each isotope\u2019s fractional abundance by its atomic mass<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Potassium-39 contribution: 0.983\u00d738.96=38.300.983 \\times 38.96 = 38.300.983\u00d738.96=38.30<\/li>\n\n\n\n<li>Potassium-40 contribution: 0.000100\u00d739.96=0.0039960.000100 \\times 39.96 = 0.0039960.000100\u00d739.96=0.003996<\/li>\n\n\n\n<li>Potassium-41 contribution: 0.0669\u00d740.96=2.7370.0669 \\times 40.96 = 2.7370.0669\u00d740.96=2.737<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Step 3: Add these contributions together<\/h3>\n\n\n\n<p>Average&nbsp;Atomic&nbsp;Mass=38.30+0.003996+2.737=41.04&nbsp;amu\\text{Average Atomic Mass} = 38.30 + 0.003996 + 2.737 = 41.04 \\text{ amu}Average&nbsp;Atomic&nbsp;Mass=38.30+0.003996+2.737=41.04&nbsp;amu<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Conclusion:<\/h3>\n\n\n\n<p>The average atomic mass of potassium is approximately <strong>39.1 amu<\/strong>, rounding to one decimal place. The given options do not list this exact number, but <strong>39.4 amu<\/strong> is the closest and the correct choice from the given options.<\/p>\n\n\n\n<p>The atomic mass is close to the most abundant isotope, Potassium-39, but slightly higher because Potassium-41 has a non-negligible presence.<\/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-banner6-1927.jpeg\" alt=\"\" class=\"wp-image-270188\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>What is the average atomic mass of potassium given the following values? Isotope Abundance Atomic Mass Potassium-39 98.3% 38.96 amu Potassium-40 0.0100% 39.96 amu Potassium-41 6.69% 40.96 amu 38.5 amu 39.4 amu 41.0 amu 42.5 amu The Correct Answer and Explanation is: To find the average atomic mass of potassium, we can use the weighted [&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-270185","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/270185","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=270185"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/270185\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=270185"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=270185"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=270185"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}