Improved analysis of isoperibol heat-pulse calorimetry

Abstract

The post-heating temperature drift curve in isoperibol heat-pulse calorimetry with isothermal shields is correctly described by an exponential function. The authors have implemented this analysis in an extended form in a small-sample (<or=10-2 mol) calorimeter with a 'tray-type' sample holder, when the external relaxation time constant is comparable to the heat-pulse duration. The analysis turned out to be particularly advantageous at temperatures above 100 K. They obtained an average scatter of about 0.07% which is nearly five times lower than the normally used linear extrapolation method and yield absolute errors below 1%.