Determination of the Temperature Change by Means of an Outcoming Signal of Electric Resistance in an Isoperibolic Calorimetric Cell. Obtainment of Heat Solution

An isoperibolic calorimetric cell is built with glass surrounded by plastic insulation. The cell has a lid on which a thermistor thermometer, an electric resistance to provide the cell with definite quantities of electric work and a container for a glass ampoule, are placed. For measuring the thermal changes, an NTC thermistor, which provides an electric resistance signal that varies with temperature, is used. Calibration curves of the thermistor and of the stabilization of the system signal in thermal equilibrium are shown, which enable the observation of a good insulation. The calorific capacity of the system with water, with a value of 206.7 ±0.7 J °C(-1) is determined; the solution enthalpy for propanol-water and KCl-water systems is obtained, which shows the behavior of the cell before exothermic and endothermic effects, respectively.