From owner-chemistry@ccl.net Sun Jul 8 05:41:00 2012 From: "Guntram Schmidt guntram.schmidt^^chemie.uni-halle.de" <owner-chemistry**server.ccl.net> To: CCL Subject: CCL: New Blog on how NOT to teach Le Chatelier's Prtinciple Message-Id: <-47178-120707174806-14761-YSQxUxpm3s55GYyHw/saDg**server.ccl.net> X-Original-From: Guntram Schmidt <guntram.schmidt**chemie.uni-halle.de> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Date: Sat, 07 Jul 2012 23:47:57 +0200 MIME-Version: 1.0 Sent to CCL by: Guntram Schmidt [guntram.schmidt.,+,.chemie.uni-halle.de] Now that's the right way to frighten off students! Instead of explaining things to the students, give them a very abstract mathematical formula without a strong relation to the outer world and let them analyze this... Do you think, this will help them UNDERSTANDING the principles of nature? If I were your student, I would ask about the meaning of a "division operation" in nature, how you dare to assign numbers to not counted (non-countable?) entities, questioning the whole measure theory itself (which is still an unanswered question)... I believe that with chemistry, we have the rare chance to teach natural sciences on the basis of easy, handmade experiments - lets try to keep having this edge over physics and biology! You asked for comments ;-), Guntram Am 07.07.2012 16:29, schrieb Eric Scerri scerri:-:chem.ucla.edu: > > http://eric1scerri.blogspot.com/ > > Comments welcome. > > regards, > eric scerri > > ________________________________________________________ > > > ericscerri.com <http://ericscerri.com/> > > On Twitter: > https://twitter.com/#!/ericscerri > > > > > > > > > > From owner-chemistry@ccl.net Sun Jul 8 16:31:00 2012 From: "VITORGE Pierre 094605 Pierre.VITORGE*o*cea.fr" <owner-chemistry**server.ccl.net> To: CCL Subject: CCL: New Blog on how NOT to teach Le Chatelier's Prtinciple Message-Id: <-47179-120708162844-14313-aJMpIV1U0dICJSAwFHE48Q**server.ccl.net> X-Original-From: VITORGE Pierre 094605 <Pierre.VITORGE|*|cea.fr> Content-Language: fr-FR Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="iso-8859-1" Date: Sun, 8 Jul 2012 20:28:32 +0000 MIME-Version: 1.0 Sent to CCL by: VITORGE Pierre 094605 [Pierre.VITORGE .. cea.fr] Could you first go back to the original citation of Le Chatelier's principle? Henri Le Chatelier, � Sur un �nonc� g�n�ral des lois des �quilibres chimiques �, dans C.R. Hebd. Seances Acad. Sci., vol. 99, 1884, p. 786-789 (ISSN 0001-4036) http://gallica.bnf.fr/ark:/12148/bpt6k3055h.image.f786.pagination.langFR The article is a discussion "of the laws of chemical equilibria" under the influence of various parameters that can shift chemical equilibria, Le Chatelier cites other authors that had already found such laws for some parameters: Le Chatelier proposed that it is actually valid for any parameter. He gives many examples. In one of them he wrote "si elle se produisait seule" which means that if you vary a parameter all the other ones should be kept constants for the reasoning He did not re-write "si elle se produisait seule" for each example, but it is obvious that he discussed or illustrated parameters one by one. As a consequence your objection with the 3H2 + N2 <-> NH3 exemple might rather be originated in a problem of translation or misunderstanding of the original publication In your blog you used the law of mass action (which is indeed a later quantitative illustration of Le Chatelier's principle) for the above example: this give uselessly complicated calculations, while the application of Le Chatelier's principle is essentially based on the comparison of 4 moles (3H2 + N2) with 1 mole (NH3). -- Pierre Vitorge Directeur de recherche CEA Laboratoire Analyse et Modelisation pour la Biologie et l Environnement, LAMBE, UMR 8587, CEA, Univ Evry, CNRS, http://www.lambe.univ-evry.fr/pvitorge http://www.vitorge.name -- Laboratoire de Radiolyse et de la Matiere Organique, LRMO CEA, DEN, Saclay, DPC, SECR, -----Message d'origine----- De�: owner-chemistry+pierre.vitorge==cea.fr/a\ccl.net [mailto:owner-chemistry+pierre.vitorge==cea.fr/a\ccl.net] De la part de Guntram Schmidt guntram.schmidt^^chemie.uni-halle.de Envoy�: samedi 7 juillet 2012 23:48 ��: VITORGE Pierre 094605 Objet�: CCL: New Blog on how NOT to teach Le Chatelier's Prtinciple Sent to CCL by: Guntram Schmidt [guntram.schmidt./a\.chemie.uni-halle.de] Now that's the right way to frighten off students! Instead of explaining things to the students, give them a very abstract mathematical formula without a strong relation to the outer world and let them analyze this... Do you think, this will help them UNDERSTANDING the principles of nature? If I were your student, I would ask about the meaning of a "division operation" in nature, how you dare to assign numbers to not counted (non-countable?) entities, questioning the whole measure theory itself (which is still an unanswered question)... I believe that with chemistry, we have the rare chance to teach natural sciences on the basis of easy, handmade experiments - lets try to keep having this edge over physics and biology! You asked for comments ;-), Guntram Am 07.07.2012 16:29, schrieb Eric Scerri scerri:-:chem.ucla.edu: > > http://eric1scerri.blogspot.com/ > > Comments welcome. > > regards, > eric scerri > > ________________________________________________________ > > > ericscerri.com <http://ericscerri.com/> > > On Twitter: > https://twitter.com/#!/ericscerrihttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt From owner-chemistry@ccl.net Sun Jul 8 23:24:00 2012 From: "Alavi, Saman Saman.Alavi_._nrc-cnrc.gc.ca" <owner-chemistry||server.ccl.net> To: CCL Subject: CCL: New Blog on how NOT to teach Le Chatelier's Principle Message-Id: <-47180-120708223430-16179-UZ1Z/jtBPM1r/gwErsUHWQ||server.ccl.net> X-Original-From: "Alavi, Saman" <Saman.Alavi-$-nrc-cnrc.gc.ca> Content-Language: en-CA Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="iso-8859-1" Date: Sun, 8 Jul 2012 22:34:22 -0400 MIME-Version: 1.0 Sent to CCL by: "Alavi, Saman" [Saman.Alavi-#-nrc-cnrc.gc.ca] There are many interesting articles and a fascinating history of the controversy surrounding the applicability of Le Chatelier's principle. The arguments are quite old, but make for very instructive reading. Some references are: B. Singh and D. Ebbing, "Le Chatelier's Theorem", Journal of Chemical Education, 33, 34 (1956) J. de Heer, "The principle of Le Chatelier and Braun", Journal of Chemical Education, 34, 375 (1957) A. Standen, "Le Chatelier, common sense, and metaphysics", Journal of Chemical Education, 35, 132 (1958) J. de Heer, "Le Chatelier, scientific principle, or sacred cow", Journal of Chemical Education, 35, 133 (1958) J. Gold and V. Gold, "Neither Le Chatelier's nor a principle?", Chemistry in Britain, 802 (September 1984) Even Paul Ehrenfest contributed to the discussion at some stage. Thermodynamically, this principle is not of much use and can be replaced by more exact mathematical formulations. Gold and Gold state that it lives on in General Chemistry books as a qualitative rule of thumb which is supposed to bring order to many diverse chemical phenomena. Its possible mis-application and numerous caveats which must be satisfied before it holds can be good arguments against including it in General Chemistry courses. However, the mystique surrounding such general rules and why they should apply may be a attractive to instructors and students. Saman ________________________________________ > From: owner-chemistry+saman.alavi==nrc.ca[*]ccl.net [owner-chemistry+saman.alavi==nrc.ca[*]ccl.net] On Behalf Of VITORGE Pierre 094605 Pierre.VITORGE*o*cea.fr [owner-chemistry[*]ccl.net] Sent: July 8, 2012 4:28 PM To: Alavi, Saman Subject: CCL: New Blog on how NOT to teach Le Chatelier's Prtinciple Sent to CCL by: VITORGE Pierre 094605 [Pierre.VITORGE .. cea.fr] Could you first go back to the original citation of Le Chatelier's principle? Henri Le Chatelier, � Sur un �nonc� g�n�ral des lois des �quilibres chimiques �, dans C.R. Hebd. Seances Acad. Sci., vol. 99, 1884, p. 786-789 (ISSN 0001-4036) http://gallica.bnf.fr/ark:/12148/bpt6k3055h.image.f786.pagination.langFR The article is a discussion "of the laws of chemical equilibria" under the influence of various parameters that can shift chemical equilibria, Le Chatelier cites other authors that had already found such laws for some parameters: Le Chatelier proposed that it is actually valid for any parameter. He gives many examples. In one of them he wrote "si elle se produisait seule" which means that if you vary a parameter all the other ones should be kept constants for the reasoning He did not re-write "si elle se produisait seule" for each example, but it is obvious that he discussed or illustrated parameters one by one. As a consequence your objection with the 3H2 + N2 <-> NH3 exemple might rather be originated in a problem of translation or misunderstanding of the original publication In your blog you used the law of mass action (which is indeed a later quantitative illustration of Le Chatelier's principle) for the above example: this give uselessly complicated calculations, while the application of Le Chatelier's principle is essentially based on the comparison of 4 moles (3H2 + N2) with 1 mole (NH3). -- Pierre Vitorge Directeur de recherche CEA Laboratoire Analyse et Modelisation pour la Biologie et l Environnement, LAMBE, UMR 8587, CEA, Univ Evry, CNRS, http://www.lambe.univ-evry.fr/pvitorge http://www.vitorge.name -- Laboratoire de Radiolyse et de la Matiere Organique, LRMO CEA, DEN, Saclay, DPC, SECR, -----Message d'origine----- De : owner-chemistry+pierre.vitorge==cea.fr*_*ccl.net [mailto:owner-chemistry+pierre.vitorge==cea.fr*_*ccl.net] De la part de Guntram Schmidt guntram.schmidt^^chemie.uni-halle.de Envoy� : samedi 7 juillet 2012 23:48 � : VITORGE Pierre 094605 Objet : CCL: New Blog on how NOT to teach Le Chatelier's Prtinciple Sent to CCL by: Guntram Schmidt [guntram.schmidt.*_*.chemie.uni-halle.de] Now that's the right way to frighten off students! Instead of explaining things to the students, give them a very abstract mathematical formula without a strong relation to the outer world and let them analyze this... Do you think, this will help them UNDERSTANDING the principles of nature? If I were your student, I would ask about the meaning of a "division operation" in nature, how you dare to assign numbers to not counted (non-countable?) entities, questioning the whole measure theory itself (which is still an unanswered question)... I believe that with chemistry, we have the rare chance to teach natural sciences on the basis of easy, handmade experiments - lets try to keep having this edge over physics and biology! You asked for comments ;-), Guntram Am 07.07.2012 16:29, schrieb Eric Scerri scerri:-:chem.ucla.edu: > > http://eric1scerri.blogspot.com/ > > Comments welcome. > > regards, > eric scerri > > ________________________________________________________ > > > ericscerri.com <http://ericscerri.com/> > > On Twitter: > https://twitter.com/#!/ericscerrihttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txthttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt