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Name: Klara
Status: student
Grade: 9-12
Location: AK
Country: USA

Does paraffin expand upon freezing?

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.

Bob Wilson


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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