:) No, a second order is not necessarily the "square" of the first order, since a first order would be first order in A, while a second order reaction could be second order in A (yes, A squared) or first order in A and first order in B, in which case you definitely would not call it squared. Bev -----Original Message----- From: Brooks,Bill [mailto:[log in to unmask]] Sent: December 17, 2003 2:35 PM To: 'TechNet E-Mail Forum.'; Bev Christian Subject: RE: [TN] Need a chemist or chemical engineer to answer Hmm.. I'm not either one... but I did try to understand your question... In English medieval alchemy, something that had sublimed had been converted by heat from a solid directly into a vapour, considered to be an ethereal or higher form of nature. As it happens, a number of substances important to alchemy sublime, including sulphur, white arsenic, amber and camphor; the device in which this was done was a sublimatory. Of course, such substances condensed again to solids when they cooled, and the word was commonly applied to the whole process of heating, vaporisation and resolidification, but the change from solid to gas was always primary. I found an explanation of Kinetics 1st and 2nd order at http://www.chemistrygeek.com/c2c13.htm The second being the square of the first? So in layman's terms... I still need more info to understand the question... but I sort of understand some of the terms... Maybe you can elaborate and help me understand the reason for the question and its implications to PCB manufacturing and Design? Bill Brooks PCB Design Engineer , C.I.D., C.I.I. -----Original Message----- From: Bev Christian [mailto:[log in to unmask]] Sent: Wednesday, December 17, 2003 10:57 AM To: [log in to unmask] Subject: [TN] Need a chemist or chemical engineer to answer Technetters, It has been almost 30 years since I took kinetics. I have dug out my old text books, but they only help so much. I'm a preparative inorganic chemist by training. My question is the following: If a single compound sublimes, without decomposition, would you expect the kinetics to be zero or first order? Thanks. Bev Christian Research in Motion --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------