{"id":86,"date":"2024-10-24T20:38:40","date_gmt":"2024-10-25T00:38:40","guid":{"rendered":"https:\/\/sites.temple.edu\/chemdemo\/?p=86"},"modified":"2024-10-25T16:22:01","modified_gmt":"2024-10-25T20:22:01","slug":"acid-strength","status":"publish","type":"post","link":"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/acid-strength\/","title":{"rendered":"Acid Strength"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Purpose<\/h2>\n\n\n\n<p>To illustrate the difference in strength between a weak acid (acetic acid) and a strong acid (hydrochloric acid).<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Procedure<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Conductivity Meter<\/h3>\n\n\n\n<p><strong>Setup:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use a light bulb conductivity meter with samples of acetic acid (HOAc) and hydrochloric acid (HCl) in solution.<\/li>\n<\/ul>\n\n\n\n<p><strong>Observation:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Show the difference in intensity of light when both acids are measured.<\/li>\n\n\n\n<li>Discuss why the difference exists (HCl dissociates into more ions).<\/li>\n<\/ul>\n\n\n\n<p><strong>Serial Dilution:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Perform a serial dilution of both acids until the light bulbs light up to an equal degree.<\/li>\n\n\n\n<li>Optionally, calculate relative strength and dissociation constant.<\/li>\n\n\n\n<li>If needed, \u201cjuice\u201d the dilute HOAc with NaCl crystals (from Shakhashiri).<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">pH Rainbow Tube<\/h3>\n\n\n\n<p><strong>Setup:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Stopper one end of a diffusion tube tightly.<\/li>\n\n\n\n<li>Place the stoppered end into a large beaker to catch any leaks.<\/li>\n\n\n\n<li>Clamp the tube in the middle using a ring stand.<\/li>\n<\/ul>\n\n\n\n<p><strong>Procedure:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Add a pellet of NaOH into the tube.<\/li>\n\n\n\n<li>Slowly pour in deionized water (dI water) mixed with universal indicator.<\/li>\n\n\n\n<li>Carefully add 2 drops of concentrated HCl to the top of the tube without agitating.<\/li>\n\n\n\n<li>Clamp vertically to the ring stand and observe the rainbow formation.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Dry Ice and NaOH<\/h3>\n\n\n\n<p><strong>Setup:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Fill a 500 mL or 1 L graduated cylinder with 1.0 M NaOH.<\/li>\n\n\n\n<li>Add universal indicator.<\/li>\n\n\n\n<li>Introduce dry ice into the cylinder.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Acidity Reactions<\/h3>\n\n\n\n<p><strong>Setup:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use 250 mL graduated cylinders with the following solutions:\n<ul class=\"wp-block-list\">\n<li>1.0 M boric acid<\/li>\n\n\n\n<li>Ethanol<\/li>\n\n\n\n<li>1.0 M acetic acid (HOAc)<\/li>\n\n\n\n<li>1.0 M hydrochloric acid (HCl)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p><strong>Observation:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Add magnesium (Mg) turnings to each solution and watch the reactions.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Titration Curves<\/h3>\n\n\n\n<p><strong>Setup:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Use a Vernier drop counter:\n<ul class=\"wp-block-list\">\n<li>Calibrate the drop counter.<\/li>\n\n\n\n<li>Plug it into DIG 1.<\/li>\n\n\n\n<li>Mount it on a ring stand with a burette filled with 0.5 M NaOH.<\/li>\n\n\n\n<li>Place a 10 mL graduated cylinder under the drop counter.<\/li>\n\n\n\n<li>Record the initial volume of the titrant.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p><strong>Procedure:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Press sensors to calibrate the drop counter and start the process.<\/li>\n\n\n\n<li>Start adding titrant at about 1 drop\/second until the 10 mL level is reached.<\/li>\n\n\n\n<li>Turn off the burette and record the burette reading.<\/li>\n\n\n\n<li>Enter the exact volume into the box on screen.<\/li>\n<\/ul>\n\n\n\n<p><strong>pH Measurement:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Attach a pH electrode to CH 1 and mount it on the drop counter.<\/li>\n\n\n\n<li>Calibrate and wash the electrode with deionized water.<\/li>\n\n\n\n<li>Place 10.0 mL of analyte (0.5 M HCl, 0.5 M HOAc, or 0.17 M H3PO4) into a 150 mL beaker.<\/li>\n\n\n\n<li>Add about 30 mL deionized water and a stir bar.<\/li>\n\n\n\n<li>Place the beaker on a magnetic stirrer under the drop counter.<\/li>\n\n\n\n<li>Immerse the pH electrode so it is protected from the stir bar but fully immersed in the analyte.<\/li>\n\n\n\n<li>Hit start and begin adding titrant.<\/li>\n\n\n\n<li>Let it run until a clear titration curve is obtained.<\/li>\n<\/ul>\n\n\n\n<p><strong>Data Analysis:<\/strong><\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Obtain the second derivative by adding an additional column to the data table.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Purpose To illustrate the difference in strength between a weak acid (acetic acid) and a strong acid (hydrochloric acid). Procedure Conductivity Meter Setup: Observation: Serial&#8230;<\/p>\n<div class=\"more-link-wrapper\"><a class=\"more-link\" href=\"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/acid-strength\/\">Continue Reading<span class=\"screen-reader-text\">Acid Strength<\/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-86","post","type-post","status-publish","format-standard","hentry","category-demonstrations","entry"],"_links":{"self":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/86","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=86"}],"version-history":[{"count":1,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/86\/revisions"}],"predecessor-version":[{"id":87,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/86\/revisions\/87"}],"wp:attachment":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/media?parent=86"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/categories?post=86"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/tags?post=86"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}