Compounds like are known as chlorofluorocarbons. These compounds were once widely used as refrigerants but are now being replaced by compounds that are believed to be less harmful to the environment. The heat of vaporization of is 289 . What mass of this substance must evaporate in order to freeze 250 of water initially at 19? (The heat of fusion of water is 334 the specific heat of water is 4.18 .)