Collection of rate data

The rate of a reaction and its dependency on the concentrations of the reactants can be measured in several ways. A simple method involves the measurement of the rate at zero to low conversion at different concentrations of one of the substrates, keeping the concentration of other substrates constant. The latter can be done by using an excess of the other substrates (e.g. tenfold excess), which means that we can assume that the concentrations of the latter ones are constant under so-called pseudo-first-order conditions. Secondly we can monitor the reaction rate over a longer period of time taking into account the change in concentration for this one substrate. Alternatively, one can monitor the concentrations of all species and analyse the results numerically. 

1) a batch reactor, in which at all times good mixing is applied and the concentrations monitored as described above, or 

2) a plug-flow reactor, in which no mixing takes place and the residence time in the tube determines the degree of conversion, or 

3) a CSTR, continuously stirred tank reactor, in which a steady state is obtained depending on the residence of the reagents in the vessel, which is also rapidly stirred so as to ensure that there are no concentration differences in the vessel. 

There are many ways to measure the concentrations of reacting species or species formed during the reaction, such as there are gc, UV-visible spectroscopy, IR spectroscopy, refiactometry, polarometry, etc. Conversion can be monitored by pressure measurements, gas-flow measurements, calorimetry, etc. Data are collected on a computer and many programmes are available for data analysis [3,4], The two-reaction system described above can be treated graphically, if it fulfils either the Bodenstein or Michaelis-Menten criteria. 

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Further, we have found that for terr-butyl bromide solvolysis (61), based on Abraham s collection of rate data (446) (solvents 18,25,28,-32,104,105,111,201) at 2S°C, the total solvatochromic equation for aliphatic solvents is... 

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