In order to carry out this experiment properly, we would need to continuously measure both the mass of the LN2 and the temperature of the aluminum cylinder as it cools in the LN2 and integrate the above relation. This would be experimentally more complex to carry out! Fortunately, most of the LN2 boil-off occurs at the higher temperatures. Thus, using the approximation that cAl is independent of temperature (with a value ~900 J/kg-K), then from measuring the total mass of LN2 boiled off, the latent heat of vaporization of nitrogen is: