{"id":206075,"date":"2025-03-26T13:10:58","date_gmt":"2025-03-26T13:10:58","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=206075"},"modified":"2025-03-26T13:10:59","modified_gmt":"2025-03-26T13:10:59","slug":"the-ka-for-hydrofluoric-acid-is-7-2-x-10-4","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/03\/26\/the-ka-for-hydrofluoric-acid-is-7-2-x-10-4\/","title":{"rendered":"The Ka for hydrofluoric acid is 7.2 \u00d7 10-4"},"content":{"rendered":"\n

The Ka for hydrofluoric acid is 7.2 \u00d7 10-4. This means that HF is<\/p>\n\n\n\n

A) neutral in water solution.<\/p>\n\n\n\n

B) able to react with HCl.<\/p>\n\n\n\n

C) a weak acid.<\/p>\n\n\n\n

D) a strong acid.<\/p>\n\n\n\n

E) ionic.<\/p>\n\n\n\n

The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n

The correct answer is C) a weak acid<\/strong>.<\/p>\n\n\n\n

Explanation:<\/h3>\n\n\n\n

The acid dissociation constant (Ka) is a measure of the strength of an acid in solution. It represents the equilibrium constant for the dissociation of an acid (HA) into its conjugate base (A-) and hydrogen ions (H+). The higher the Ka value, the stronger the acid, because a stronger acid dissociates more completely in water.<\/p>\n\n\n\n

For hydrofluoric acid (HF), the Ka value is 7.2 \u00d7 10\u207b\u2074<\/strong>. This is a relatively small value, which means that only a small fraction of the HF molecules dissociate into ions in water. This behavior is characteristic of weak acids<\/strong>.<\/p>\n\n\n\n

Key points about weak acids:<\/h3>\n\n\n\n
    \n
  • A weak acid dissociates only partially in water, meaning that at equilibrium, a significant proportion of the acid molecules remain undissociated.<\/li>\n\n\n\n
  • A higher Ka (greater than 1) corresponds to a stronger acid that dissociates almost completely in water (e.g., HCl or HNO\u2083).<\/li>\n\n\n\n
  • Weak acids like HF have a Ka less than 1, and since 7.2 \u00d7 10\u207b\u2074 is much less than 1, HF is a weak acid.<\/li>\n<\/ul>\n\n\n\n

    Why not the other options?<\/h3>\n\n\n\n
      \n
    • A) Neutral in water solution<\/strong>: HF is not neutral. A neutral solution would have a pH of 7, but HF dissociates slightly to produce H+ ions, making the solution acidic (pH < 7).<\/li>\n\n\n\n
    • B) Able to react with HCl<\/strong>: HF is not typically known for reacting with HCl. Both are acids, and generally, acids do not react with each other unless there are specific conditions.<\/li>\n\n\n\n
    • D) A strong acid<\/strong>: HF is not a strong acid because it does not dissociate completely in water. Strong acids like HCl, HNO\u2083, and H\u2082SO\u2084 dissociate completely.<\/li>\n\n\n\n
    • E) Ionic<\/strong>: HF is a molecular compound and not ionic. It does dissociate into ions in solution, but it is not an ionic compound to begin with.<\/li>\n<\/ul>\n\n\n\n

      Image of HF dissociation:<\/h3>\n\n\n\n
      \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

      The Ka for hydrofluoric acid is 7.2 \u00d7 10-4. This means that HF is A) neutral in water solution. B) able to react with HCl. C) a weak acid. D) a strong acid. E) ionic. The correct answer and explanation is : The correct answer is C) a weak acid. Explanation: The acid dissociation constant […]<\/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-206075","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/206075","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=206075"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/206075\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=206075"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=206075"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=206075"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}