{"id":256545,"date":"2025-07-16T10:16:56","date_gmt":"2025-07-16T10:16:56","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=256545"},"modified":"2025-07-16T10:16:59","modified_gmt":"2025-07-16T10:16:59","slug":"the-molecular-weight-of-potassium-chloride-kcl-is-74-55-g-mol","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/07\/16\/the-molecular-weight-of-potassium-chloride-kcl-is-74-55-g-mol\/","title":{"rendered":"The molecular weight of Potassium chloride (KCl) is 74.55 g\/mol."},"content":{"rendered":"\n<p><br>The molecular weight of Potassium chloride (KCl) is 74.55 g\/mol. How many grams would you need for 650 ml of a 35 mM solution?<\/p>\n\n\n\n<p>The Correct Answer and Explanation is:<\/p>\n\n\n\n<p><strong>Correct Answer:<\/strong><br><strong>1.7 grams of KCl<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p><strong>Explanation:<\/strong><\/p>\n\n\n\n<p>To determine how many grams of potassium chloride (KCl) are needed to prepare <strong>650 milliliters (ml)<\/strong> of a <strong>35 millimolar (mM)<\/strong> solution, we follow a step-by-step approach using the <strong>molarity formula<\/strong> and <strong>molecular weight<\/strong>.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 1: Understand the relationship<\/h3>\n\n\n\n<p><strong>Molarity (M)<\/strong> is defined as the number of <strong>moles of solute per liter of solution<\/strong>.<br>We are given:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Volume = 650 ml = 0.650 liters (since 1000 ml = 1 liter)<\/li>\n\n\n\n<li>Molarity = 35 mM = 0.035 mol\/L (since 1000 mM = 1 mol)<\/li>\n\n\n\n<li>Molecular weight of KCl = 74.55 g\/mol<\/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\">Step 2: Calculate the number of moles of KCl required<\/h3>\n\n\n\n<p>Use the formula:<\/p>\n\n\n\n<p><strong>moles = molarity \u00d7 volume<\/strong><\/p>\n\n\n\n<p>moles of KCl = 0.035 mol\/L \u00d7 0.650 L = <strong>0.02275 mol<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 3: Convert moles to grams<\/h3>\n\n\n\n<p>Use the molecular weight to convert moles to grams:<\/p>\n\n\n\n<p><strong>mass (g) = moles \u00d7 molecular weight<\/strong><\/p>\n\n\n\n<p>mass = 0.02275 mol \u00d7 74.55 g\/mol = <strong>1.695 grams<\/strong><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">Step 4: Round the answer<\/h3>\n\n\n\n<p>Rounding <strong>1.695 grams<\/strong> to <strong>1 decimal place<\/strong>, we get:<\/p>\n\n\n\n<p><strong>1.7 grams<\/strong><\/p>\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<p>To prepare <strong>650 ml of a 35 mM potassium chloride (KCl) solution<\/strong>, you would need to weigh out and dissolve <strong>1.7 grams<\/strong> of KCl in enough water to make up <strong>650 ml<\/strong> of solution. This calculation is essential in chemistry labs to ensure solutions have the correct concentration for accurate experimental results.<\/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-banner6-649.jpeg\" alt=\"\" class=\"wp-image-256546\"\/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The molecular weight of Potassium chloride (KCl) is 74.55 g\/mol. How many grams would you need for 650 ml of a 35 mM solution? The Correct Answer and Explanation is: Correct Answer:1.7 grams of KCl Explanation: To determine how many grams of potassium chloride (KCl) are needed to prepare 650 milliliters (ml) of a 35 [&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-256545","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256545","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=256545"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/256545\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=256545"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=256545"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=256545"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}