{"id":37706,"date":"2025-06-26T04:40:50","date_gmt":"2025-06-26T04:40:50","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=37706"},"modified":"2025-06-26T07:38:26","modified_gmt":"2025-06-26T07:38:26","slug":"for-each-reaction-order-identify-the-proper-units-for-the-rate-constant-k-not-all-of-the-choices-will-be-used","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/for-each-reaction-order-identify-the-proper-units-for-the-rate-constant-k-not-all-of-the-choices-will-be-used\/","title":{"rendered":"For each reaction order: identify the proper units for the rate constant; k. Not all of the choices will be used"},"content":{"rendered":"\n<p>For each reaction order: identify the proper units for the rate constant; k. Not all of the choices will be used: Zero order First order Second order Third order M . $ M&#8221; Answcr Bank M<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"444\" src=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-343.png\" alt=\"\" class=\"wp-image-37707\" srcset=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-343.png 1024w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-343-300x130.png 300w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/image-343-768x333.png 768w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n<p>Here are the correct units for the rate constant kk for each reaction order:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Zero order<\/strong>: Not listed in the answer bank<\/li>\n\n\n\n<li><strong>First order<\/strong>: 1\/s<\/li>\n\n\n\n<li><strong>Second order<\/strong>: 1\/(M\u00b7s)<\/li>\n\n\n\n<li><strong>Third order<\/strong>: M\u00b2\/s<\/li>\n<\/ul>\n\n\n\n<p><strong>Explanation:<\/strong><\/p>\n\n\n\n<p>The rate constant kk in a chemical rate law must carry units that balance the equation so that the rate of reaction always has units of concentration over time, typically expressed as M\/s (molarity per second).<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li><strong>Zero-order reactions<\/strong> follow the rate law:<\/li>\n<\/ol>\n\n\n\n<p>rate=k\\text{rate} = k<\/p>\n\n\n\n<p>Since rate has units of M\/s, kk must also have units of M\/s. However, this unit is not present in the provided answer bank, so we disregard it for this task.<\/p>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li><strong>First-order reactions<\/strong> follow:<\/li>\n<\/ol>\n\n\n\n<p>rate=k[A]\\text{rate} = k[A]<\/p>\n\n\n\n<p>Here,<\/p>\n\n\n\n<p>k=rate[A]k = \\frac{\\text{rate}}{[A]}<\/p>\n\n\n\n<p>Substituting units:<\/p>\n\n\n\n<p>k=M\/sM=1\/sk = \\frac{\\text{M\/s}}{\\text{M}} = 1\/\\text{s}<\/p>\n\n\n\n<p>So the proper unit from the answer bank is 1\/s.<\/p>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li><strong>Second-order reactions<\/strong> typically follow:<\/li>\n<\/ol>\n\n\n\n<p>rate=k[A]2ork[A][B]\\text{rate} = k[A]^2 \\quad \\text{or} \\quad k[A][B]<\/p>\n\n\n\n<p>Rearranging gives:<\/p>\n\n\n\n<p>k=rate[A]2orM\/sM2=1\/(M\\cdotps)k = \\frac{\\text{rate}}{[A]^2} \\quad \\text{or} \\quad \\frac{\\text{M\/s}}{\\text{M}^2} = 1\/(\\text{M\u00b7s})<\/p>\n\n\n\n<p>So the correct unit from the bank is 1\/(M\u00b7s).<\/p>\n\n\n\n<ol start=\"4\" class=\"wp-block-list\">\n<li><strong>Third-order reactions<\/strong> may be written as:<\/li>\n<\/ol>\n\n\n\n<p>rate=k[A]3ork[A]2[B]ork[A][B][C]\\text{rate} = k[A]^3 \\quad \\text{or} \\quad k[A]^2[B] \\quad \\text{or} \\quad k[A][B][C]<\/p>\n\n\n\n<p>In all cases:<\/p>\n\n\n\n<p>k=M\/sM3=M\u22122\/sk = \\frac{\\text{M\/s}}{\\text{M}^3} = \\text{M}^{-2}\/\\text{s}<\/p>\n\n\n\n<p>This is equivalent to M\u00b2\/s when rearranged with positive exponents for the given unit style.<\/p>\n\n\n\n<p>These units are essential in determining the rate law from experimental data and in modeling reaction kinetics across various chemical contexts.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"852\" height=\"1024\" src=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner8-955.jpeg\" alt=\"\" class=\"wp-image-37708\" srcset=\"https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner8-955.jpeg 852w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner8-955-250x300.jpeg 250w, https:\/\/gaviki.com\/blog\/wp-content\/uploads\/2025\/06\/learnexams-banner8-955-768x923.jpeg 768w\" sizes=\"auto, (max-width: 852px) 100vw, 852px\" \/><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>For each reaction order: identify the proper units for the rate constant; k. Not all of the choices will be used: Zero order First order Second order Third order M . $ M&#8221; Answcr Bank M The Correct Answer and Explanation is: Here are the correct units for the rate constant kk for each reaction [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-37706","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/37706","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=37706"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/37706\/revisions"}],"predecessor-version":[{"id":37709,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/37706\/revisions\/37709"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=37706"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=37706"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=37706"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}