Question

A sample with the phase diagram below starts at room temperature (25oC) and 1 atm. What phase change would the sample go through if it was cooled to 80 K?

a)Condensation (gas to liquid)

B)Fusion (solid to liquid)

C)Deposition (gas to solid)

D)Vaporization (liquid to gas)

E)Sublimation (solid to gas)

F)Freezing (liquid to solid)

Answer 1

Answer: C)Deposition (gas to solid)

Explanation: According to the phase diagram, at room temperature (25°C) and 1 atm, the sample is in the gas phase. As the temperature decreases to 80 K, it falls below the sublimation curve. T he sublimation curve represents the conditions at which a substance can change directly from a solid to a gas or from a gas to a solid without passing through the liquid phase.

Since the sample is in the gas phase at room temperature, cooling it to 80 K would cause it to go through the process of deposition, where the gas particles directly transform into a solid without first becoming a liquid. This is indicated by the section of the phase diagram below the sublimation curve.