Can sublimation be used to identify a substance?

Answer 1

In theory, yes. In practice, this would be a difficult endeavor. Sublimation involves the change from the solid to gaseous state of matter. Inspection of a phase diagram will show that sublimation happens only in a narrow range of temperature and pressure. For many common substances this range is outside the standard temperature and pressure regions and therefore would require specialized equipment to carry out the analysis.

For substances whose sublimation ranges do include the standard pressure region, the analysis would be relatively simple: heat the substance until it begins to sublime, noting the temperature range from beginning to end of the process. One could possibly even use the standard MelTemp apparatus.

For substances whose sublimation ranges do include the standard temperature region, a pressure vessel could be designed to hold the substance at constant temperature while varying the pressure and making the observation noted in the paragraph above.

Answer 2

Yes, sublimation can be used to help identify a substance. By observing the temperature at which a solid directly transitions to a gas, known as the sublimation point, and comparing it to known values, scientists can make connections to the identity of the substance. Additionally, the appearance of the sublimed material can also provide clues about its identity.

Answer 3

It's possible to identify elements based on the difference in energy between various electronic energy levels; this is how we can determine the chemical composition of stars.