{"id":90,"date":"2024-10-24T20:44:20","date_gmt":"2024-10-25T00:44:20","guid":{"rendered":"https:\/\/sites.temple.edu\/chemdemo\/?p=90"},"modified":"2024-10-25T16:22:01","modified_gmt":"2024-10-25T20:22:01","slug":"thermodynamics","status":"publish","type":"post","link":"https:\/\/sites.temple.edu\/chemdemo\/2024\/10\/24\/thermodynamics\/","title":{"rendered":"Thermodynamics"},"content":{"rendered":"\n

Rubber band thermodynamics<\/u><\/strong>–  Office supplies are used to explore enthalpy, entrophy and Gibbs free energy<\/p>\n\n\n\n

Purpose<\/strong>:\u00a0 To allow students to figure out the thermodynamics of a common office supply. <\/p>\n\n\n\n

Procedure<\/strong>:\u00a0 Give all students a rubber band and write the \u201creaction\u201d stretched going to unstretched on the board.\u00a0 Ask students about spontaneity of this reaction.\u00a0 Stretch a rubber band and point it in general direction of professor.\u00a0 Say that if have a stretched rubber band it will \u201cspontaneously\u201d fly at someone.\u00a0 Get the sign of \u0394G.\u00a0 Then move on to enthalpy.\u00a0 Have students hold rubber band against face while stretched out for a little while.\u00a0 Then have them allow it to relax and check the temperature change.\u00a0 Talk about heat flow for this process and record sign of \u0394H.\u00a0 Then talk about entropy.\u00a0 Have them deduce sign.\u00a0 Ask if makes sense.\u00a0 Have students hold rubber band in stretched out position and try to wiggle it.\u00a0 Shouldn\u2019t move much.\u00a0 Then have them hold a relaxed rubber band and repeat.\u00a0 Also, can use larger model of linked rubber bands and ruler to show how system becomes rigid.\u00a0 Record sign for entropy.\u00a0<\/p>\n\n\n\n

Rubber Band Thermodynamics<\/u><\/strong><\/p>\n\n\n\n

Perform the following experiment<\/p>\n\n\n\n

    \n
  1. Stretch and hold the rubber band for twenty seconds.<\/li>\n\n\n\n
  2. Touch stretched rubber band to the skin directly above your upper lip or forehead. (Not where your fingers are holding the rubber band.)<\/li>\n\n\n\n
  3. Quickly relax rubber band while still against you lip or forehead. (DO NOT LET GO of RUBBER BAND! Try not to thwack yourself or your neighbor!)<\/li>\n<\/ol>\n\n\n\n

    Q1: What did you notice?<\/p>\n\n\n\n

    Q2:  Is this a spontaneous or non-spontaneous reaction?<\/p>\n\n\n\n

    Q3:\u00a0 What is the sign of \u0394G?<\/p>\n\n\n\n

    Q5:\u00a0Are the molecules in the band becoming more ordered or disordered during the forward reaction?\u00a0<\/p>\n\n\n\n

    \u00a0Q4: What is the sign of \u0394H for the rubber band going from stretched to contracted?<\/p>\n\n\n\n

    Q6: What is the sign of \u0394S?<\/p>\n\n\n\n

     Q7: Are the intermolecular forces breaking or forming during the forward reaction?<\/p>\n\n\n\n

     Q8: Will this process be spontaneous at all temperatures?<\/p>\n\n\n\n

    <\/p>\n","protected":false},"excerpt":{"rendered":"

    Rubber band thermodynamics–  Office supplies are used to explore enthalpy, entrophy and Gibbs free energy Purpose:\u00a0 To allow students to figure out the thermodynamics of…<\/p>\n

    Continue ReadingThermodynamics<\/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-90","post","type-post","status-publish","format-standard","hentry","category-demonstrations","entry"],"_links":{"self":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/90","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=90"}],"version-history":[{"count":1,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/90\/revisions"}],"predecessor-version":[{"id":91,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/posts\/90\/revisions\/91"}],"wp:attachment":[{"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/media?parent=90"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/categories?post=90"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.temple.edu\/chemdemo\/wp-json\/wp\/v2\/tags?post=90"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}