810.7 Methods for Studying fast reactions Levine: pp 569-572 17.14 Fast reactions
§10.7 Methods for Studying fast reactions Levine: pp. 569-572. 17.14 Fast reactions
8 10.7 Study of fast reactions 10.7.1 Basic consideration What is fast reaction? a fast reaction is that can proceed very fast and complete in less than few seconds Examples: Neutralization reaction, explosion reaction and recombination reaction of radicals Basic characteristics: 1)The activation energy of fast reaction is usually less than 40 kJ mol-l and with k s high as 10 dm mol-s- (2) This kind of reaction is difficult to study using ordinary methods
What is fast reaction? A fast reaction is that can proceed very fast and complete in less than few seconds. Basic characteristics: (1) The activation energy of fast reaction is usually less than 40 kJ mol -1 and with k as high as 1011 dm3 mol-1 s -1 . (2) This kind of reaction is difficult to study using ordinary methods. Examples: Neutralization reaction, explosion reaction and recombination reaction of radicals §10.7 Study of fast reactions 10.7.1 Basic consideration:
8 10.7 Study of fast reactions 10.7.1 Basic consideration Methods for measuring reaction rate The physical parameters usually used for monitoring reaction process includes volume, pressure, electric conductance, pH, refractive index, thermal conductivity, polarimetry, spectrometry, chromatography, etc. 1)Real time analysis 1)Static method Quenching Analyzing methods 2)Flow method
The physical parameters usually used for monitoring reaction process includes volume, pressure, electric conductance, pH, refractive index, thermal conductivity, polarimetry, spectrometry, chromatography, etc. Analyzing methods: 1) Static method 2) Flow method 1) Real time analysis 2) Quenching Methods for measuring reaction rate §10.7 Study of fast reactions 10.7.1 Basic consideration:
8 10.7 Study of fast reactions 10.7.1 Basic consideration Generator Reaction Detector Methods for recording time msμs—>ns—>ps—>fs
§10.7 Study of fast reactions 10.7.1 Basic consideration: Methods for recording time ms⎯→s ⎯→ns ⎯→ps ⎯→fs Generator Reaction cell Detector
10.7 Reaction rate and rate equation 10.7.2 Continuous flow method Attain a steady-state flow The coordination reaction between Fe2+ and Mixer detector thiocyanate SCN- in aqueous solution Moving direction Stable flow:/o t Distance corresponds to time B v=10 m s-I step of0. 1 mm corresponds to 10 us Measurements are done using a stepwise method
10.7 Reaction rate and rate equation Stable flow: l t Mixer detector Moving direction A B Attain a steady-state flow: The coordination reaction between Fe2+ and thiocyanate, SCN– , in aqueous solution. Distance corresponds to time v = 10 m s-1 , step of 0.1 mm corresponds to 10 s. Measurements are done using a stepwise method. 10.7.2 Continuous flow method