To study the changes in the state of sublimate solids on heating.
Sublimation is the process by which substances transition from one state to another, such as from solid to gas. Sublimation transfers material from the solid to the gaseous phase without transitioning to the liquid phase. This endothermic phase transition happens at temperatures and pressures lower than the substance's triple point. The triple point is the point at which a substance's pressure and temperature are such that it may exist simultaneously in all three states of matter. A substance's triple point is a distinguishing feature. DE sublimation, also known as deposition, is the process by which a gas is turned directly into a solid state.
Solid ⇌ Vapour (gas)
The chemistry behind the reaction based on the experiment
Ammonium chloride changes directly from solid to gaseous state on heating. Hence, on heating ammonium chloride, it gets converted into white vapours. The gaseous form of ammonium chloride can be cooled easily to get a pure solid.
Ammonium chloride is NH4Cl, which decomposes into ammonia and hydrochloric acid when heated by the process of thermal decomposition.
This dissociated molecule recombines on cooling to form NH4Cl
Dissociation is a physical change that also happens to be a chemical change because the change is reversible.
Examples of sublimation
Note: Sublimation occurs more efficiently when the air is dry, and the ice is near the melting point of water.
Application of Sublimation