Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Densest Fluid
Name: Chris J.
Status: other
Grade: other
Location: AP

What is the densest liquid known?

Hi Chris,

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 to Mercury!

Bob Wilson.

"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 16.6 gm/cm^3.

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.

Vince Calder

Click here to return to the Material Science Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory