How would you perform an activity to understand the process of sublimation?
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Solution
Sublimation:
The process of changing of solid state directly into the gaseous state without passing through the liquid state on heating is known as sublimation.
The solid substance which undergoes sublimation is known as sublime and the substance obtained by cooling the vapors of solid is known as sublimate.
Example:
Solids such as Iodine, Camphor, Naphthalene, and Ammonium chloride change directly into the gaseous state on heating without passing through the liquid state.
An activity to understand the process of sublimation:
Procedure:
Take some camphor or Ammonium chloride.
Crush it and put it in a china dish.
Put an inverted funnel over the china dish.
Put a cotton plug on the stem of the funnel to prevent the escape of ammonium chloride vapors into the atmosphere, as shown in the figure below.
Now, heat the china dish slowly with the help of a burner and observe.
Experimental set-up for the sublimation of ammonium chloride:
Observation:
On heating the solid ammonium chloride does not melt.
As crystalline solid on coming in contact with the cold inner walls of the funnel it is directly converted into vapors and gets deposited on the inner wall of the funnel.
Conclusion:
A change of state directly from solid to gas without changing into a liquid state or vice versa is called sublimation.
