Name: Kevin M.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 2000
Question:
Why does temperature remain constant during a phase change?
Replies:
Kevin,
As an example, consider melting an ice cube: As heat is added to the cube, the
energy serves to break water molecules from the ice latticework. Rather
than to
raise the temperature of the surrounding water, the heat is used to
continue the
melting process -- to continue breaking water molecules from the lattice. The
temperature of the surrounding water cannot rise until the ice has completely
melted. At that time, additional heat will raise the temperature of the
melt-water.
The same is true for the reverse process. As water is cooled and allowed to
freeze, energy is released from the bonds that are formed as water molecules
become incorporated into the ice latticework. That released energy holds the
temperature constant until all the liquid water has been frozen. Continued
cooling thereafter will reduce the temperature if the ice cube.
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