Practice question · Multiple choice
Why does the solid-liquid coexistence line of water slope backwards?
Hints
- The slope’s sign is set by the sign of the volume change in the Clapeyron equation.
- Ice floats, so melting it REDUCES the volume.
Show the answer
A. Ice is less dense than liquid water, making the volume change negative on melting
Why
In , melting ice has because ice is the less dense phase, so the slope is negative. Almost every other substance has a denser solid and a forward-sloping line.
Practise Phase Transitions and Critical Phenomena
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