Problem 2. Liquid nitrogen, which has a boiling point of 77 K, is commonly used to cool substances to low temperatures. How much energy must be removed from 1.4 kg of gaseous nitrogen at 77 K for it to completely liquefy? Assume the latent heat of liquid nitrogen is 2.01 *10^5 J/kg Answer in units of J. Problem 4. You have collected exactly 2200 aluminum cans for recycling, each with a mass of 14.1 g. How much energy is needed to melt them if their initial temperature is 26.8 degrees C? Assume the specific heat, the latent heat and the melting point of aluminum are 899 J/kg * degrees C, 3.97*10^5 J/kg and 660.4degreesC respectively. An- swer in units of J.