Reducing the experimental error in an experiment to determine the latent heat of vaporization of liquid nitrogen

Abstract

In this work, modifications are made to a fairly simple laboratory experiment to experimentally determine the latent heat of vaporization with a substantially lower error than those previously reported. A new experimental technique of using an asynchronous data capture method is proposed for use with an adiabatic calorimeter for measurement as it isolates the measurement vessel from changes in the surroundings affecting the measured quantity. Further modifications are made to the experiment to determine the power at each instant the rate of mass drop is measured within the measurement range to ensure the errors associated with varying power resulting from resistance fluctuations are also minimized. The asynchronous data capture method proposes the use of computer control for the entire experiment, which again reduces the error in terms of delays in human reaction time. Applying these three new techniques to the experiment enables the latent heat of [Formula: see text] to be determined experimentally and results in a substantially lower error bar attached to the final value for the latent heat of vaporization of liquid nitrogen. The value of Lv = 201.2 ± 0.194 J/g differs by approximately 1% from the accepted value of 199.0 J/g (G.W.C. Kaye and T.H. Laby. Tables of physical and chemical constants, fifteenth edition. Longman, London. 1995). Sources of systematic (experimental) error are suggested and estimated for in this experiment and thus this small discrepancy is accounted for.