Question

Which phase change at standard temperature and pressure represents sublimation?

Answer 1

The phase change at standard temperature and pressure that represents sublimation is the transition from solid to gas. Carbon dioxide (dry ice) and iodine are examples of substances that undergo sublimation at these conditions.

Step-by-step explanation:

The phase change at standard temperature and pressure (STP) that represents sublimation is the direct transition from solid to gas without passing through the liquid phase. Substances like carbon dioxide (CO₂), commonly known as dry ice, and iodine are known to undergo sublimation at STP conditions. For instance, dry ice sublimes at −78 °C and atmospheric pressure, making it a classic example of sublimation. On the other hand, water requires conditions below its triple point pressure of 0.00600 atm to sublime; this process is utilized in freeze-drying foods.

Answer 2

Substances on Earth can exist in three phases namely, solid, liquid or gas. The phase can be changed from one to other by any of six changes of phase: melting, condensation, freezing, vaporization, decomposition or sublimation.

Chemical process in which a solid turns to a gas without going to liquid stage is known as sublimation. It is an endothermic (absorbs heat) process. For example: Transformation of dry ice (solid carbon dioxide) to vapors to form clouds.

Hence, phase change at standard temperature and pressure which represents sublimation is solid turns to a gas without going to liquid stage.