{"id":31852,"date":"2025-06-22T09:00:34","date_gmt":"2025-06-22T09:00:34","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=31852"},"modified":"2025-06-22T09:00:36","modified_gmt":"2025-06-22T09:00:36","slug":"the-pka-of-hydrofluoric-acid-hf-is-3-17","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/the-pka-of-hydrofluoric-acid-hf-is-3-17\/","title":{"rendered":"The pKa of hydrofluoric acid, HF is 3.17"},"content":{"rendered":"\n<p>The pKa of hydrofluoric acid, HF is 3.17. The pKb of sodium fluoride, NaF, is<\/p>\n\n\n\n<p><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\"><strong>The correct answer and explanation is:<\/strong><\/mark><\/p>\n\n\n\n<p>The pKa of hydrofluoric acid (HF) is 3.17. Sodium fluoride (NaF) is a salt derived from the weak acid HF and the strong base NaOH. When NaF dissolves in water, it dissociates into Na\u207a and F\u207b ions. The fluoride ion (F\u207b) is the conjugate base of HF.<\/p>\n\n\n\n<p>The relationship between pKa and pKb for a conjugate acid-base pair is given by:<\/p>\n\n\n\n<p>pKa+pKb=14pK_a + pK_b = 14<\/p>\n\n\n\n<p>This equation assumes the solution is at 25\u00b0C, where the ion product of water (Kw) is 1\u00d710\u2212141 \\times 10^{-14}.<\/p>\n\n\n\n<p>Given:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>pKapK_a of HF = 3.17<\/li>\n<\/ul>\n\n\n\n<p>To find the pKb of the fluoride ion (F\u207b), use:<\/p>\n\n\n\n<p>pKb=14\u2212pKapK_b = 14 &#8211; pK_a<\/p>\n\n\n\n<p>Substitute the given value:<\/p>\n\n\n\n<p>pKb=14\u22123.17=10.83pK_b = 14 &#8211; 3.17 = 10.83<\/p>\n\n\n\n<p>Therefore, the pKb of the fluoride ion (from NaF) is 10.83.<\/p>\n\n\n\n<p><strong>Explanation<\/strong><\/p>\n\n\n\n<p>Hydrofluoric acid (HF) is a weak acid with a pKa of 3.17. This means it only partially dissociates in water to release H\u207a ions. The fluoride ion (F\u207b) is its conjugate base, formed when HF loses a proton. Since HF is weak, its conjugate base F\u207b is relatively strong, but not a strong base; it can accept protons but does so weakly.<\/p>\n\n\n\n<p>pKa and pKb measure the strength of acids and bases. The lower the pKa, the stronger the acid; the lower the pKb, the stronger the base. Because HF is a weak acid, its conjugate base has a high pKb value, indicating weak basicity.<\/p>\n\n\n\n<p>The sum of pKa and pKb equals 14 at 25\u00b0C, reflecting the ionization balance in water. This allows one to calculate the pKb of a conjugate base if the pKa of its acid is known.<\/p>\n\n\n\n<p>Knowing the pKb of fluoride ion helps predict the behavior of NaF solutions. Because the fluoride ion is a weak base, NaF solutions tend to be slightly basic in water, affecting pH and equilibrium in buffer solutions involving HF\/NaF pairs. This concept is essential for understanding buffer chemistry and acid-base equilibria in aqueous systems.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The pKa of hydrofluoric acid, HF is 3.17. The pKb of sodium fluoride, NaF, is The correct answer and explanation is: The pKa of hydrofluoric acid (HF) is 3.17. Sodium fluoride (NaF) is a salt derived from the weak acid HF and the strong base NaOH. When NaF dissolves in water, it dissociates into Na\u207a [&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-31852","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/31852","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=31852"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/31852\/revisions"}],"predecessor-version":[{"id":31853,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/31852\/revisions\/31853"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=31852"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=31852"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=31852"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}