Why is sublimation an effective technique for the isolation of pure caffeine? Select one or more: The impurities of caffeine synthesis are expected to decompose at high temperatures. The purified caffeine will vaporize and can be collected as a solid, leaving impurities behind. When heated, caffeine will sublime at a lower temperature than it melts. The synthesis of caffeine tends not to produce impurities, so a more thorough purification technique is not needed