Q1.
Observe the inner wall of the funnel carefully. Do you notice any solid deposits?
Answer
Yes — a layer of white solid camphor collects on the cool inner wall of the inverted funnel, while the sand stays behind in the china dish.
Camphor (solid) —heat→ camphor vapour —cooling on the funnel wall→ camphor (solid)
Solid → vapour directly = sublimation
Vapour → solid directly = deposition
Solid → vapour directly = sublimation
Vapour → solid directly = deposition
Why it happens: On gentle heating (kept below its melting point) camphor passes straight from the solid state to the vapour state without ever becoming a liquid — its particles gain enough energy to escape from the solid surface directly. The vapour rises and meets the funnel wall, which is much cooler because it is exposed to the room air. There the vapour loses energy and settles straight back into the solid state. Sand does not sublime at these temperatures, so it is left in the dish. The mixture is separated because one component sublimes and the other does not.
Tip: The cotton plug in the funnel nozzle is not decoration — it stops the camphor vapour from escaping so that all of it condenses inside the funnel. Naphthalene, ammonium chloride and dry ice (solid carbon dioxide) also sublime and can be used the same way.