{"id":84,"date":"2024-10-24T20:35:23","date_gmt":"2024-10-25T00:35:23","guid":{"rendered":"https:\/\/sites.temple.edu\/chemdemo\/?p=84"},"modified":"2024-10-25T16:22:01","modified_gmt":"2024-10-25T20:22:01","slug":"acidic-and-basic-salts","status":"publish","type":"post","link":"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/acidic-and-basic-salts\/","title":{"rendered":"Acidic and Basic Salts"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Purpose<\/h2>\n\n\n\n<p>To help the class learn to identify ions as weak acids and bases.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Procedure<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Solutions Preparation:<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Prepare 1 M solutions of:\n<ul class=\"wp-block-list\">\n<li>Sodium chloride (NaCl)<\/li>\n\n\n\n<li>Sodium acetate (Na+CH3COO-)<\/li>\n\n\n\n<li>Sodium carbonate (Na2CO3)<\/li>\n\n\n\n<li>Aluminum chloride (AlCl3)<\/li>\n\n\n\n<li>Ammonium chloride (NH4Cl)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Prediction Activity:<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Display a universal indicator color chart on the document camera.<\/li>\n\n\n\n<li>Allow students to discuss predictions with neighbors.<\/li>\n\n\n\n<li>Have students raise hands to show their predictions.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Testing:<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Test the solutions by adding universal indicator.<\/li>\n\n\n\n<li>Discuss conjugate pairs based on the results.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Bonus Activity:<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Fill a large graduated cylinder with water and universal indicator.<\/li>\n\n\n\n<li>Repeat the prediction procedure using dry ice.<\/li>\n\n\n\n<li>Note that dilute coloration is most visible on the projector.<\/li>\n\n\n\n<li><strong>Important:<\/strong> Test sodium acetate ahead of time, as it may need to be made fresh due to bacterial spoilage.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Ionization Constants<\/h2>\n\n\n\n<p><strong>Ammonium Chloride (NH4Cl)<\/strong><\/p>\n\n\n\n<p>NH4<sup>+<\/sup>\u200b + H2\u200bO \u21cc NH3 \u200b+ H3\u200bO<sup>+<\/sup><\/p>\n\n\n\n<p>K<sub>a<\/sub>\u200b = 7.5\u00d710<sup>\u22123<\/sup><\/p>\n\n\n\n<p>pK<sub>a<\/sub>\u200b = 2.12<\/p>\n\n\n\n<p><strong>Sodium Chloride (NaCl)<\/strong><\/p>\n\n\n\n<p>Neutral salt; does not affect pH.<\/p>\n\n\n\n<p><strong>Aluminum Chloride (AlCl3)<\/strong><\/p>\n\n\n\n<p>Al<sup>3+<\/sup> + H2\u200bO \u21cc Al(OH)<sup>2+<\/sup> + H3\u200bO<sup>+<\/sup><\/p>\n\n\n\n<p>K<sub>a<\/sub>\u200b = 4.3 \u00d7 10<sup>\u22127<\/sup><\/p>\n\n\n\n<p>pK<sub>a<\/sub>\u200b = 6.37<\/p>\n\n\n\n<p><strong>Sodium Acetate (Na+CH3COO-)<\/strong><\/p>\n\n\n\n<p>H2\u200bO + CH3\u200bCOOH \u21cc CH3\u200bCOO\u2212 + H3\u200bO+<\/p>\n\n\n\n<p>Ka \u200b= 1.8\u00d710<sup>\u22125<\/sup><\/p>\n\n\n\n<p>pK<sub>a<\/sub> \u200b= 4.74<\/p>\n\n\n\n<p><strong>Sodium Carbonate (Na2CO3)<\/strong><\/p>\n\n\n\n<p>H2\u200bO + H2\u200bCO3\u200b \u21cc HCO3\u2212 \u200b+ H3\u200bO+<\/p>\n\n\n\n<p>Ka \u200b= 5.6 \u00d7 10<sup>\u221211<\/sup><\/p>\n\n\n\n<p>pK<sub>a<\/sub> = 10.5<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Additional Notes<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Kb and pKb for ammonia:<\/li>\n\n\n\n<li>NH3\u200b + H2\u200bO \u21cc NH4\u200bOH + OH\u2212<\/li>\n\n\n\n<li>K<sub>b<\/sub>\u200b=1.76\u00d710<sup>\u22125<\/sup><\/li>\n\n\n\n<li>pK<sub>b<\/sub> = 4.75<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Purpose To help the class learn to identify ions as weak acids and bases. Procedure Ionization Constants Ammonium Chloride (NH4Cl) NH4+\u200b + H2\u200bO \u21cc NH3&#8230;<\/p>\n<div class=\"more-link-wrapper\"><a class=\"more-link\" href=\"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/acidic-and-basic-salts\/\">Continue Reading<span class=\"screen-reader-text\">Acidic and Basic Salts<\/span><\/a><\/div>\n","protected":false},"author":36673,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-84","post","type-post","status-publish","format-standard","hentry","category-demonstrations","entry"],"_links":{"self":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/84","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/users\/36673"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/comments?post=84"}],"version-history":[{"count":1,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/84\/revisions"}],"predecessor-version":[{"id":85,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/84\/revisions\/85"}],"wp:attachment":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/media?parent=84"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/categories?post=84"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/tags?post=84"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}