Chaos in Chemistry
in Thai language


Mechanism of BZ reaction

                        ¡Ò÷ӤÇÒÁà¢éÒ㨠dynamical system ¢Í§»¯Ô¡ÔÃÔÂÒ BZ  ¨Óà»ç¹µéͧà¢éÒ㨷ÕèÁҢͧÊÁ¡Ò÷Õè¡Ó˹´ reaction kinetic ¢Í§»¯Ô¡ÔÃÔÂÒÍѹ¡Ó˹´â´Â mechanism ¢Í§ overall BZ reaction «Öè§à»ç¹¾×é¹°Ò¹·ÕèÊӤѭ â´Â mechanism ¢Í§»¯Ô¡ÔÃÔÂÒ BZ ¹Õé¾Ñ²¹Òâ´Â Field-Koros-Noyes(FKN) ·ÕèÁËÒÇÔ·ÂÒÅÑ Oregon àÃÒ¨Ö§àÃÕ¡ mechanism ¢Í§ BZ ¹ÕéÇèÒ Oregonator model ËÃ×Í FKN model â´Â¨Ð¹ÔÂÁ Oregonator ÁÒ¡¡ÇèÒ à¾ÃÒÐÁÕÃٻẺ·ÕèàËÁÒÐÊÁ¡ÇèÒ â´Âã¹»¯Ô¡ÔÃÔÂÒÃÇÁ¨Ð¾ºÇèÒÁÕ species µèÒ§æ ¹éÍÂÁÒ¡ áµè㹤ÇÒÁà»ç¹¨ÃÔ§áÅéÇÁÕ species áÅÐ intermediate ÁÒ¡ÁÒÂËÅÒµÑÇ ËÒ¡µéͧ¡ÒÃÈÖ¡ÉÒÅÐàÍÕ´àªÔ­ÍèÒ¹ä´é·Õè J. Am. Chem. Soc., 94, 1972, 8649 ¨ÐäÁè¼Ô´ËÇѧ áµèã¹ homepage ¹Õé¨Ð͸ԺÒÂã¹ÀÒ¾ÃÇÁ·Õè¨ÐàËç¹ÀÒ¾ä´éªÑ´´éÇ FKN model  áÅШÐáÊ´§ mathematical derived ´éÇ Oregonator ·ÕèÊдǡ㹷ҧ¤³ÔµÈÒʵÃìÁÒ¡¡ÇèÒ
                        ¨Ò¡ FKN model ·ÕèµÑ´àÍÒ»¯Ô¡ÔÃÔÂÒÂèÍ·ÕèäÁèÁռŵèÍ»¯Ô¡ÔÃÔÂÒÃÇÁÍÍ¡ä» àËÅ×Íáµè»¯Ô¡ÔÃÔÂÒ·ÕèÊӤѭà·èÒ¹Ñé¹â´Âáºè§à»ç¹ Process µèÒ§ æ 3 ¢Ñé¹´éÇ¡ѹ ¤×Í Process A ·ÕèÁÕ¡ÒáӨѴ [Br-] ÍÍ¡, Process B ·ÕèÁÕ Autocatalysis ¢Í§ HBrO2 à¡Ô´¢Öé¹  áÅÐã¹ Process C ·ÕèÁÕ¡ÒÃÊÃéÒ§ [Br-] ¡ÅѺÁÒÍÕ¡¤ÃÑé§ ä´é´Ñ§¹Õé
                        ¢Ñé¹ÊӤѭ㹠Process A
(FKN3)  BrO3- + Br- + 2H+ --> HBrO2 + HOBr  â´ÂÁÕ rate = k3[BrO3-][Br-][H+]2
(FKN2) HBrO2 + Br- + H+ -->  HOBr                 â´ÂÁÕ rate = k2[HBrO2][Br-][H+]
Process A :   BrO3- + 2Br- + 3H+ -->   3HOBr
                        ¨Ò¡»¯Ô¡ÔÃÔÂÒ¢éÒ§º¹ã¹ process A ¾ºÇèÒ bromide ion ¨Ð¶Ù¡¡Ó¨Ñ´ÍÂèÒ§ÃÇ´àÃçÇä»à»ç¹ HOBr «Ö觨ÐÁÕ¼Åâ´ÂµÃ§µèÍ process C àÁ×èÍ bromide ion Ŵŧ¶Ö§¨Ø´Ë¹Öè§áÅéÇ»¯Ô¡ÔÃÔÂҨРshift ä»ÂѧÍÕ¡ species ¹Ñ蹤×Í HBrO2 ·Õè¨Ðà»ÅÕè¹ä»à»ç¹ HOBr ´éÇ FKN2 «Ö觨ش¹Õè¨Ðà»ç¹¨Ø´àÃÔèÁ Process B ·Õèà»ç¹
                        Process B
(FKN5)   BrO3- + HBrO2  + H+ <--> 2BrO2í + H2 â´ÂÁÕ rate = k5[BrO3-][HBrO2 ][H+] - k5[HBrO]
(FKN6)  BrO2í + Mred + H+  -->  HBrO2 + Mox     â´ÂÁÕ rate = k6[BrO2í ][Mred][H+]
Process B :  BrO3- + HBrO2  + 2Mred + 3H+ -->  2HBrO2 + 2Mox + H2O
                        â´ÂàÁ×è;ԨÒóһ¯Ô¡ÔÃÔÂÒ FKN-5(»¯Ô¡ÔÃÔÂÒÂé͹¡ÅѺ¢Í§ FKN5) áÅéÇá·º¨ÐäÁèà¡Ô´¢Öé¹ ·ÓãËéä´é BrO2í à¡Ô´¢Öé¹à»ç¹  balance ÃÐËÇèÒ§ FKN5 áÅÐ FKN6 àÁ×è;ԨÒÃ³Ò Process B ÃÇÁ ¨Ðà»ç¹¡ÒÃà¾ÔèÁ»ÃÔÁÒ³µÑÇàͧ¢Í§HBrO2 ·ÕèàÃÕ¡ÇèÒ Autocatalysis ¢Í§ HBrO2  «Öè§¡ÒÃà¡Ô´ HBrO2 ¢Ö鹡Ѻ FKN5 «Öè§à»ç¹¼ÅãËéÁÕ [HBrO2] à¾ÔèÁ¢Öé¹  áµèÍÂèÒ§äáç´Õ¡ÒÃà¾ÔèÁ¢Í§ HBrO2 ¶Ù¡¤Çº¤ØÁâ´Â self-disproportionation reaction ¢Í§ HBrO2 ¹Ñè¹àͧ
                (FKN4)  2HBrO2  -->  BrO3- + HOBr + H+             â´ÂÁÕ rate = k4[HBrO2]2
«Öè§¡ÒÃà»ÅÕè¹ Process ¨Ò¡ A ä» B à¡Ô´¢Öé¹àÁ×èÍ rate ã¹ FKN5 à¡×ͺà·èҡѹ¡Ñº FKN2 áÅéÇËÒ [Br-] ·ÕèàÃÔèÁà¡Ô´ Autocatalysis ã¹ process B  ´Ñ§¹Ñé¹ HBrO2 áÊ´§µÑÇà»ç¹ inhibitor ¢Í§ Br- ¹Ñè¹àͧ   áÅÐã¹ FKN4 ·Õè·ÓãËé [Br-] Ŵŧä»ÍÕ¡àÁ×èÍà¡Ô´ autocatalysis à¾ÃÒÐÁÕ¡ÒÃÊѧà¤ÃÒÐËì BrO3- ¢Öé¹ áÅÐàÁ×èÍ [Br-] ŴŧÁÒ¨¹¶Ö§ critical bromide ion concentration «Öè§à·èҡѺ
               k2[HBrO2][Br-][H+]       =     k5[BrO3-][HBrO2 ][H+]
                                      [Br-]cr     =  (k5/k2)[BrO3-]  = 1.4 x 10-5[BrO3-]
                        àÁ×èͶ֧ [Br-]cr  áÅéǨÐÁÕ¡ÒüèÒ¹¢Ñ鹵͹ Process B ä» C·ÕèÁÕ¡ÒÃà¡Ô´ autocatalytic acceleratory oxidation of metal ion catalyst ä´éá¡è
Process C :  2Mox + MA + BrMA --> fBr- + 2Mred + other product ·ÕèÁÕ rate = kc[Org][Mox]
àÁ×è;ԨÒÃ³Ò Process C  BrMA( Bromomalonic acid ) ¹Ñé¹à¡Ô´¨Ò¡ HOBr ·Õèà¾ÔèÁ¢Ö鹨ҡ process A áÅÐ Mox ·Õèä´é¨Ò¡ process B
â´Â·Ñé§ MA (malonic acid) áÅÐ BrMA (bromomalonic acid) ÅéǹáÅéÇáµè¨Ð·Ó»¯Ô¡ÔÃÔÂҡѺ Mox ·Ñ駤Ùè áÅéÇä´é Bromide ion ¡ÅѺ¤×¹
áµè¤èÒ stoichiometric factor f ¢Í§ bromide ion à»ç¹ parameter ·Õè adjust ¤èÒä´é ¶éÒ Mox ·Ó»¯Ô¡ÔÃÔÂÒ੾ÒСѺ BrMA áÅéÇ f = 2, ËÒ¡ f > 2/3 áÅéÇ net concentration ¢Í§ Br- ¨Ðà¾ÔèÁ¢Öé¹·Ø¡Ãͺ¢Í§¡Òà oscillate   ¹Í¡¨Ò¡¹Õé f  ÂѧÁÕ¤èÒä´éËÅÒ¤èÒµÒÁ MA , BrMA, HOBr áÅÐÍÕ¡ËÅÒ æ intermediate species áµèÍÂèÒ§äáçµÒÁ rate ¢Í§ process C ¡ç¢Ö鹡Ѻ¤ÇÒÁà¢éÁ¢é¹¢Í§ Org species ¡çä´é «Öè§»ÃÐÁÒ³ä´éà·èҡѺ¤ÇÒÁà¢éÁ¢é¹àÃÔèÁµé¹¢Í§ MA ¹Ñè¹àͧ