The Chemical Equilibrium between Nitrogen Dioxide and Dinitrogen Tetroxide. An Introductory Experiment in Chemical Thermodynamics

A simple experimental procedure using syringes for determining the temperature dependence of the equilibrium constant for the chemical equilibrium between NO2 and N2O4 is proposed as a suitable laboratory activity for an introductory experiment in chemical thermodynamics at universities and colleges. Using their experimental data, students construct fundamental thermodynamic plots, where the relationships among the thermodynamic parameters for the chemical equilibrium can be clearly illustrated. As a result, fairly appropriate values of thermodynamic parameters, for instance, ΔH0, ΔS0, and ΔG0, can be evaluated. On the basis of the thermodynamic parameters, it is possible to make students consider the thermodynamic properties of the dimerization reaction of NO2 to N2O4.