Isoperibolic Calorimetry Applied To The Pt/D$_2$O Blank System

Doubts have often been expressed about the precision and accuracy of isoperibolic calorimeters where the heat transfer is controlled by radiation across the vacuum gap of the Dewar cells. Therefore, experiments were conducted on blank systems consisting of Pt cathodes polarized in 0.1 M LiOD/D$_2$O. Both the differential and intergral heat transfer coefficients were evaluated, and the latter based on backward integration of the data sets should be used for accurate evaluations of the experimental data. The heat transfer coefficients obtained are in agreement with values given by the product of the Stefan-Boltzmann coefficient and the radiant surface area. It is shown that the precision of this calorimetry is better than 99.99 percent while the accuracy is close to this figure. This high precision and accuracy allows the determination of the rate of enthalpy generation due to the reduction of oxygen electrogenerated in the cell. This rate was 0.0011 W for oxygen reduction whereas the input enthalpy to the cell was about 0.8 W for these experiments.