CONSTRUCTION OF A ROTATING-BOMB COMBUSTION CALORIMETER AND MEASUREMENT OF THERMAL EFFECTS

ABSTRACT Based on an RBC-I type rotating-bomb calorimeter, an RBC-II type rotating-bomb calorimeter with digital indicator, wherein an integrated circuit is employed, aiming at promoting the precision and accuracy of the experimental thermochemistry, is developed. The accuracy uncertainty of the present calorimeter has been reduced from 1.6 × 10−3 to 4.68 × 10−4 by calibration with the standard benzoic acid. The constant volume combustion enthalpies of the new complexes of Cr(His)(NO3)3 3H2O (A), Cr(His)2(NO3)3 3H2O (B), and Cr(His)3(NO3)3 3H2O (C) have been determined by the RBC-II type rotating-bomb calorimeter. The standard formation enthalpies of the complexes have been calculated; they are −1160.22±2.64 kJ mol−1, −1844.91±4.33 kJ mol−1, and −5400±5.08 kJ mol−1, respectively.