{"id":184786,"date":"2025-01-21T15:38:26","date_gmt":"2025-01-21T15:38:26","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=184786"},"modified":"2025-01-21T15:38:27","modified_gmt":"2025-01-21T15:38:27","slug":"why-does-cds-dissolve-in-hcl","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/01\/21\/why-does-cds-dissolve-in-hcl\/","title":{"rendered":"Why does CdS dissolve in HCl"},"content":{"rendered":"\n

Why does CdS dissolve in HCl, when CuS and Bi2S3 will not?<\/p>\n\n\n\n

The Correct Answer and Explanation is :<\/strong><\/mark><\/p>\n\n\n\n

Cadmium sulfide (CdS) dissolves in hydrochloric acid (HCl), while copper sulfide (CuS) and bismuth sulfide (Bi\u2082S\u2083) do not, due to differences in the solubility product constants (K(_{sp})) of these sulfides and their ability to form soluble complexes in acidic conditions.<\/p>\n\n\n\n

Explanation:<\/h3>\n\n\n\n
    \n
  1. Solubility Product (K(_{sp})):<\/strong><\/li>\n<\/ol>\n\n\n\n
      \n
    • CdS has a relatively higher K(_{sp}) compared to CuS and Bi\u2082S\u2083, meaning it is less insoluble in water. Thus, CdS can partially dissociate into Cd\u00b2\u207a and S\u00b2\u207b ions, making it more reactive in acidic conditions.<\/li>\n\n\n\n
    • CuS and Bi\u2082S\u2083 have much lower K(_{sp}) values, making them highly insoluble and less reactive to acids.<\/li>\n<\/ul>\n\n\n\n
        \n
      1. Reaction with HCl:<\/strong><\/li>\n<\/ol>\n\n\n\n
          \n
        • When HCl is added to CdS, the hydrogen ions (H\u207a) react with the sulfide ions (S\u00b2\u207b) to form hydrogen sulfide gas (H\u2082S):
          [
          CdS + 2H\u207a \\rightarrow Cd^{2+} + H_2S
          ]<\/li>\n\n\n\n
        • This reaction is favored because H\u2082S is a weak acid and easily escapes as a gas, shifting the equilibrium and enhancing CdS dissolution.<\/li>\n<\/ul>\n\n\n\n
            \n
          1. Complex Formation:<\/strong><\/li>\n<\/ol>\n\n\n\n
              \n
            • Cadmium ions (Cd\u00b2\u207a) can also form soluble chloride complexes such as ([CdCl_4]^{2-}), further driving the dissolution of CdS in HCl.<\/li>\n<\/ul>\n\n\n\n
                \n
              1. Resistance of CuS and Bi\u2082S\u2083:<\/strong><\/li>\n<\/ol>\n\n\n\n
                  \n
                • CuS and Bi\u2082S\u2083 do not dissolve because their sulfide ions are more tightly bound in the solid lattice, and the strong H\u207a from HCl cannot displace them easily.<\/li>\n\n\n\n
                • Additionally, Cu\u00b2\u207a and Bi\u00b3\u207a ions do not form highly stable chloride complexes in acidic solutions, further reducing their solubility.<\/li>\n<\/ul>\n\n\n\n

                  In summary, CdS dissolves in HCl due to its higher K(_{sp}), the release of H\u2082S gas, and the formation of soluble Cd\u00b2\u207a complexes, while the low K(_{sp}) and chemical stability of CuS and Bi\u2082S\u2083 prevent their dissolution.<\/p>\n","protected":false},"excerpt":{"rendered":"

                  Why does CdS dissolve in HCl, when CuS and Bi2S3 will not? The Correct Answer and Explanation is : Cadmium sulfide (CdS) dissolves in hydrochloric acid (HCl), while copper sulfide (CuS) and bismuth sulfide (Bi\u2082S\u2083) do not, due to differences in the solubility product constants (K(_{sp})) of these sulfides and their ability to form soluble […]<\/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-184786","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/184786","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=184786"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/184786\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=184786"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=184786"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=184786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}