There are way in separating mixtures of chlorides salts such as that of sodium chloride and ammonium chloride. It can be done by crystallization, filtration or sublimation. The easiest method among the three is separation by sublimation.
Ammonium chloride sublimes upon heating. Actually, the sublimation is a decomposition of ammonium chloride forming ammonia and hydrogen chloride. The reaction can be written as:
`NH_4Cl _((s)) -> NH_3_(g) + HCl_((g))`
Sodium chloride on the other hand doesn't sublime and has a higher melting point than ammonium chloride. If we want to separate the mixture, we have to heat up to 330-350 degrees Celsius and collect the gas that will be produced.