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Title: Spatial Heterogeneity and Imperfect Mixing in Chemical Reactions: Visualization of Density-Driven Pattern Formation

Imperfect mixing is a concern in industrial processes, everyday processes (mixing paint, bread machines), and in understanding salt water-fresh water mixing in ecosystems. The effects of imperfect mixing become evident in the unstirred ferroin-catalyzed Belousov-Zhabotinsky reaction, the prototype for chemical pattern formation. Over time, waves of oxidation (high ferriin concentration, blue) propagate into a background of low ferriin concentration (red); their structure reflects in part the history of mixing in the reaction vessel. However, it may be difficult to separate mixing effects from reaction effects. We describe a simpler model system for visualizing density-driven pattern formation in an essentially unmixed chemical system: the reaction of pale yellow Fe 3 + with colorless SCN to form the blood-red Fe ( SCN ) 2 + complex ion in aqueous solution. Careful addition of one drop of Fe ( NO 3 ) 3 to KSCN yields striped patterns after several minutes. The patterns appear reminiscent of Rayleigh-Taylor instabilities and convection rolls, arguing that pattern formation is caused by density-driven mixing.
Authors:
 [1] ;  [2] ;  [2]
  1. Department of Chemistry, Hofstra University, Hempstead, NY 11549-1510, USA
  2. Department of Physics and Astronomy, Hofstra University, Hempstead, NY 11549-1510, USA
Publication Date:
OSTI Identifier:
1198248
Grant/Contract Number:
FG02-08ER64623
Type:
Published Article
Journal Name:
Research Letters in Physical Chemistry
Additional Journal Information:
Journal Volume: 2009; Related Information: CHORUS Timestamp: 2016-08-11 09:09:57; Journal ID: ISSN 1687-6873
Publisher:
Hindawi Publishing Corporation
Sponsoring Org:
USDOE
Country of Publication:
Country unknown/Code not available
Language:
English