Multiple Choice
In a phase diagram, at which temperature does a substance vaporize under standard atmospheric pressure?
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13. Liquids, Solids & Intermolecular Forces
Phase Diagrams
Multiple Choice
Which of the following best describes what occurs when a substance melts?
A
The substance transitions from the gas phase to the solid phase as its particles lose energy and become fixed.
B
The substance transitions from the liquid phase to the gas phase as its particles escape into the atmosphere.
C
The substance transitions from the liquid phase to the solid phase as its particles slow down and arrange into a regular pattern.
D
The substance transitions from the solid phase to the liquid phase as its particles gain enough energy to overcome their fixed positions.
Verified step by step guidance1
Understand the definition of melting: Melting is the phase transition where a substance changes from the solid phase to the liquid phase.
Recall the behavior of particles in different phases: In a solid, particles are closely packed in a fixed, orderly arrangement and vibrate in place; in a liquid, particles have more freedom to move around but remain close together.
Recognize that melting occurs when particles in a solid gain enough energy (usually from heat) to overcome the forces holding them in fixed positions, allowing them to move more freely and form a liquid.
Note that melting is not a transition from gas to solid, nor from liquid to gas, nor from liquid to solid; these correspond to other phase changes (deposition, vaporization, and freezing, respectively).
Therefore, the best description of melting is: the substance transitions from the solid phase to the liquid phase as its particles gain enough energy to overcome their fixed positions.
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