Using the personal computer, multichannel data acquisition is possible for plural samples. Measurement of freezing point depression of benzene is demostrated for determination of molecular weight of acetic acid. One of typical application of PC is to help a person from simple, dull and long-term jobs. Also, it makes possible to carry out more precise and convincing measurement free from artificial errors. Here, it is shown that temperatures of plural samples are measured simultaneously. You can obtain plural cooling curves at the same time.
Although this is a demostration experiment, the analysis is carried out by yourselves. Just the difference from the ones made by each pair is that data obtained is electromotive force of thermocouple instead of reading of the Beckmann thermometer.
Employed Measurement System
The measurement system employed here is shown in
the figure.
Each sample is put into the double fold test tube to place in the ice bath. Temeperature measurements are carried out by Cupper-Constantan thermocouples (Cu-Con TC) inserted to the sample using thinned glass tube. Digital multimeter (DMM-2000; Keithley Inc.) installed with 10 ch of mutlichannel scanner card is used for the measurement of electromotive force (EMF) of Cu-Con TC. The DMM-2000 is connected to and controlled by personal computer (PC-9821Ne; NEC) via GP-IB bus. On the PC, a GP-IB interface (GP-IB(PM); CONTEC) of PCMCIA card type is installed.
Software used for control is developed by a BASIC language (QuickBASIC for MS-DOS; Microsoft Inc.). If somebody needs this program, I can provide it for free. However, it is not generic program which does not work in other combination of systems.
Results of Measurement
Refer to this link for results of PC
demonstration.