Name: Chris J.
What is the densest liquid known?
I am assuming you mean, what is the densest fluid measured at
room temperature. If so, I believe the answer is Mercury. If
you want to get a little hotter (that is, about 5500°F!), I
suspect it is liquid Osmium, since solid Osmium (at nearly 23
times heavier than water is the heaviest solid known.
Mercury, by contrast is a "mere" 13.5 times heavier than
water. Perchloroethylene, the solvent used in dry cleaning,
is heavier than most common fluids, but still is only about
1.6 times the density of water; a real lightweight compared
"The densest liquid known" has no unique answer because the
density of a liquid (or more precisely, a fluid) depends upon
the temperature and pressure. Of the common elements, mercury
(at 25 C.) has a density of 13.6 gm/cm^3. However, Plutonium
at its melting point -- about 650 C. -- has a density of about
Now, if you do not limit the scope of the question to temperatures
below the critical point of a substance, then the density can have
almost any value, depending on the applied pressure and the melting
point of the substance.
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Update: June 2012