Data acquisition system for chemical kineticstudies

摘要

A microcomputer-interfaced data acquisition system for chemicalkinetics (interfacing with laboratory analogue instruments) hasbeen developed. Analogue signals from instruments used in kineticsexperiments are amplifed by a wide-range adjustable high-gainoperational amplifier and smoothed by an op-based filter, and thendigitized at rates of up to 104samples per channel by an ADC0816 digitizer. The ADC data transfer and manipulation routinewas written in Assembler code and in high-level language; thegraphics package and data treatment package is in Basic. For thevarious sampling speeds, all of the program can be written usingBasic-Assembler or completely in Assembler if a high samplingrate is needed. Several numerical treatment methods for chemicalkinetics have been utilized to smooth the data from experiments.The computer-interfaced system for second-order chemical kineticstudies was applied to the determination of the rate constant of thesaponification of ethyl acetate at 35°C. For this specific problem,an averaging treatment was used which can be called an intervalmethod. The use of this method avoids the diffcully of measuringthe starting time of the reaction. Two groups of experimental dataand results were used to evaluate the systems performance. All of theresults obtained are in agreement with the reference value.