Question
Why CaO is used for drying NH3 but not conc. H2SO4?
Answer
CaO reacts with NH3 to form calcium hydroxide [Ca(OH)2] and ammonium nitrate [NH4NO3]. This reaction removes the moisture content from NH3 and makes it dry. In contrast, when conc. H2SO4 is added to NH3, it reacts with it to form ammonium sulfate [(NH4)2SO4], which is a salt and does not remove moisture content.
