Task id16965

To determine the degree of thermal insulation of a Dewar flask, ice was placed in it at 0°C; 42 g of ice melted in 24 hours. Liquid nitrogen is usually stored in this dewar at a temperature of 78 K. Assuming that the amount of heat entering the dewar is proportional to the temperature difference inside and outside the vessel, determine how much nitrogen will evaporate per day. Ambient air temperature 20°C, heat of evaporation of nitrogen at normal pressure 1.8 105 J/K.