Sublimation
Chemistry ⇒ States of Matter
Sublimation starts at 7 and continues till grade 12.
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See sample questions for grade 12
A mixture contains naphthalene and sodium chloride. Which method would you use to separate them and why?
A sample of dry ice is left at room temperature. What will you observe after some time?
A student heats a mixture of ammonium chloride and sodium chloride. Only white fumes are observed and collected on a cold surface. Which process is responsible for this observation?
Calculate the enthalpy of sublimation if the enthalpy of fusion is 10 kJ/mol and the enthalpy of vaporization is 40 kJ/mol.
Describe the difference between sublimation and evaporation.
Describe the molecular changes that occur during sublimation.
Describe the role of pressure in the sublimation of solids.
Explain why camphor balls shrink in size when left exposed to air for a long time.
Explain why dry ice is used to create fog effects in stage performances.
Explain why iodine crystals appear to 'disappear' when heated gently in an open dish.
Explain why not all solids can sublime under normal conditions.
Explain why sublimation is used as a purification technique for certain solids.
Name two common substances that undergo sublimation at atmospheric pressure.
Which process is the opposite of sublimation?
A 2.00 g sample of iodine is heated in a closed container at 25°C. After some time, the mass of solid iodine decreases to 1.50 g. Calculate the mass of iodine vapor formed, assuming no iodine escapes the container.
A chemist wants to purify a sample of benzoic acid contaminated with a non-volatile impurity. Explain how sublimation can be used for this purpose and describe the steps involved.
A student claims that sublimation is always a reversible process. Critically evaluate this statement.
Explain, with reference to molecular structure, why ionic solids like sodium chloride do not undergo sublimation under normal atmospheric conditions.
The phase diagram of carbon dioxide shows that at 1 atm pressure, solid CO2 does not melt but sublimes directly to gas. Explain why this occurs, referring to the phase diagram.
