The Experimental Determination of the Heat Capacity of Gaseous Ozone

Abstract

The mean heat capacity of ozone between 300 and 476°K has been determined from explosions of mixtures of ozone and oxygen in a spherical bomb by the method the authors described in a previous paper. The value obtained is 10.94 calories per mol of ozone. The value obtained from band spectra is 10.39 calories per mol. The difference cannot be accounted for by incorrect assignment of the optical frequencies of ozone, and it is larger than the probable experimental error. It is proposed that the difference may be due to a contribution to the heat capacity of an electronic level lying close to the ground state of the ozone molecule. It is estimated that this supposed level has an energy of 0.1 to 0.2 volt. The existence of low-energy electronic levels probably implies an isosceles triangle structure and paramagnetic properties of the ozone molecule in the normal and the low excited states.