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Question
Ammonium chloride is also a sublimable solid. Give a reason why the sublimation of ammonium chloride involves a physical and a chemical change.
Solution
Sublimation of ammonium chloride – [NH4C1]
Ammonium chloride sublimes on heating and dissociates into ammonia [NH3] and hydrogen chloride [HC1], which recombine on cooling to give back – NH4C1
\[\ce{NH4Cl [s] ⇌ NH3 [g] + HCl [g]}\]
Dissociation is a chemical change.
Hence, the sublimation of such substances involves both – a physical and a chemical change.
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