High precision calorimetric apparatus for studying electrolysis reactions

We have developed a low cost continuous flow labyrinth calorimetric system which attains 0.3% accuracy in absolute energy balance and has a minimum sensitivity of 20 mW. This system is ideally suited to measure the energy balance of electrolytic reactions for output powers ranging from 0 to at least 25 W. By employing a catalyst to recombine the gaseous reaction products, the electrolysis cell can be operated as a closed system, thus eliminating many uncertainties associated with calorimetric measurements on open cell electrolytic processes. Careful calibrations using different electrical heater configurations inside the calorimeter demonstrate insensitivity to temperature gradients and local heating. We present measurements of energy balances of electrolytic reactions using Pd and Pt cathodes in 0.1 M LiOD in D2O as electrolyte. No anomalies are observed in the energy balance of either sample.