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Paraffin Expansion and Freezing
Name: Klara
Status: student
Grade: 9-12
Location: AK
Country: USA
Question:
Does paraffin expand upon freezing?
Replies:
Paraffin shrinks as it gets colder (that's true for its phase change, and
also for both liquid and solid forms).
Water (which expands upon freezing) is quite unusual. Most things expand
when heated and shrink when cooled.
Hope this helps,
Burr Zimmerman
Hi Klara,
Actually, quite the opposite. Paraffin wax expands significantly when
it melts, and it shrinks when it freezes. Water is one of the very few
liquids that expands when it freezes.
Regards,
Bob Wilson
Klara,
Paraffin wax (solid) typically has a density of 0.9g/mL, whereas paraffin oil
(liquid) has a density of 0.8g/mL. This means that paraffin contracts (rather
than expands) upon freezing. The data varies a bit because paraffin is a
mixture of different molecules or compounds. But the values are reasonably
consistent.
Another indication that paraffin does become more dense upon cooling is the
"lava lamp", when the paraffin is heated it becomes less dense and rises to
the top of the lamp. When it reaches the top, it cools and becomes more dense
and sinks.
Greg (Roberto Gregorius)
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Update: June 2012
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