{"id":64,"date":"2024-10-24T14:49:42","date_gmt":"2024-10-24T18:49:42","guid":{"rendered":"https:\/\/sites.temple.edu\/chemdemo\/?p=64"},"modified":"2024-10-25T16:22:13","modified_gmt":"2024-10-25T20:22:13","slug":"supersaturation","status":"publish","type":"post","link":"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/supersaturation\/","title":{"rendered":"Supersaturation"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Purpose<\/h2>\n\n\n\n<p>To illustrate solubility rules for solids in liquids and gases in liquids.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Procedure<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Supersaturated Solution of Sodium Acetate<\/h3>\n\n\n\n<p><strong>Preparation<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Take some sodium acetate trihydrate in a test tube and \u201cmelt\u201d it by heating with a Bunsen burner. This dissolves it in its own waters of hydration.<\/li>\n\n\n\n<li>Once fully dissolved, gently drip in some water to form a barrier against premature crystallization (keep this layer thin on top of the saturated solution).<\/li>\n<\/ul>\n\n\n\n<p><strong>Cooling<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Allow the solution to cool for a while.<\/li>\n\n\n\n<li>Prepare multiple test tubes, ensuring that at least one contains some leftover crystals to create a saturated solution upon cooling.<\/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>Compare the stable saturated solution with the unstable supersaturated solutions.<\/li>\n\n\n\n<li>Introduce a nucleation site for crystal growth by adding another crystal of sodium acetate and observe the results.<\/li>\n<\/ul>\n\n\n\n<p><strong>Alternative Method<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>This demonstration can also be conducted using a commercial hand warmer with a metal disk inside.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Key Concepts<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Discuss how solubility is affected by temperature.<\/li>\n\n\n\n<li>Explain nucleation and seed crystals.<\/li>\n\n\n\n<li>Define unsaturation, saturation, and supersaturation.<\/li>\n\n\n\n<li>Optionally reference &#8220;Ice 9&#8221; for fans of Kurt Vonnegut.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Gas Solubility Demonstration<\/h3>\n\n\n\n<p><strong>Soda Examination<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Show a sealed bottle of Diet Coke and ask students whether it is saturated, unsaturated, or supersaturated.<\/li>\n\n\n\n<li>Open the bottle and discuss how it becomes supersaturated.<\/li>\n<\/ul>\n\n\n\n<p><strong>Flat Soda<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Ask what happens to soda when it goes back to being saturated (it becomes flat).<\/li>\n\n\n\n<li>Explain that this is a slow process in a smooth container and that nucleation sites are needed for bubble formation.<\/li>\n<\/ul>\n\n\n\n<p><strong>Mentos Reaction<\/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 Mentos candy to the soda after discussing how its rough surface acts as a nucleation site.<\/li>\n\n\n\n<li>Conduct this in a clear plastic tote for easy cleanup.<\/li>\n<\/ul>\n\n\n\n<p><strong>Prediction and Experiment<\/strong>:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Have students predict whether a bottle kept in hot water or ice water will produce a bigger fountain (lose more CO\u2082).<\/li>\n\n\n\n<li>Get a volunteer to help conduct the experiment.<\/li>\n\n\n\n<li>Discuss how solubility differs in warm versus cold conditions. Use three Mentos per 20 oz. bottle for optimal results.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Additional Concepts<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Osmosis and Dialysis<\/strong>:<\/li>\n\n\n\n<li>Discuss concepts involving dialysis tubing, starch, sugar, and iodine (refer to Shakhashiri, Vol. 3, page 290).<\/li>\n\n\n\n<li><strong>Salting Out<\/strong>:<\/li>\n\n\n\n<li>Explain the salting out process (refer to Shakhashiri, Vol. 3, page 266).<\/li>\n\n\n\n<li><strong>Volume Changes on Mixing<\/strong>:<\/li>\n\n\n\n<li>Consider discussing the effects of volume changes when mixing different solutions.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Purpose To illustrate solubility rules for solids in liquids and gases in liquids. Procedure Supersaturated Solution of Sodium Acetate Preparation: Cooling: Observation: Alternative Method: Key&#8230;<\/p>\n<div class=\"more-link-wrapper\"><a class=\"more-link\" href=\"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/supersaturation\/\">Continue Reading<span class=\"screen-reader-text\">Supersaturation<\/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-64","post","type-post","status-publish","format-standard","hentry","category-demonstrations","entry"],"_links":{"self":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/64","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=64"}],"version-history":[{"count":1,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/64\/revisions"}],"predecessor-version":[{"id":65,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/64\/revisions\/65"}],"wp:attachment":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/media?parent=64"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/categories?post=64"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/tags?post=64"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}