The heat of vaporization of a refrigerant is 1370 J/g. Calculate how many kilograms of refrigerant must be evaporated to freeze a tray of 16 one-ounce (1oz= 28g) ice cubes starting with the water at 18C. The heat capacity of water = 4.184 J/g*C and deltaH_fusion(water)= 330 J/g.