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 Density and Surface Tension
Name: Heather
Status: student
Age: N/A
Location: N/A
Country: N/A
Date: N/A


Question:
Does the density of a liquid affect its surface tension?



Replies:
The quick answer is that no, density and surface tension are not tightly related. You can find examples of all four combinations dense-high-tension, dense-low-tension, low-density-high-tension, and low-density-low-tension.

That is not to say there is no relationship though. This question can get very complicated very quickly, so I will try to be brief -- the nature of the molecules involved and how attractive they are to each other or to other molecules (such as on a surface) affect both density and surface energy. Molecules that are strongly attracted to each other tend to have higher surface tension and higher density. However, since molecules can be very different -- small molecules like water, intermediate molecules like organic alcohols, and large molecules like polymers -- and one place on a molecule can be chemically different than another place, many possibilities exist.

Hope this helps,

Burr Zimmerman


It all depends upon the geometry of the liquid setup -- bubbles, foams, flat surface -- the relation between surface tension and density is different for each case. A common arrangement is the rise of a column of liquid in a uniform capillary of radius 'r'. In this case, the liquid will rise in the capillary a height 'h' which is given by: 1/2 x (h x d x g x r) = S. Here, 'd' is the density of the liquid, 'g' is the gravitational constant, and 'S' is the surface tension. This capillary rise is used to measure the surface tension of liquids. A word of caution, however. Because surface tension is a "surface phenomenon" it is subject to minute changes in the liquid, the surface in contact, and other experimental variables -- it is not an easy property to measure accurately.

Vince Calder



Click here to return to the Physics 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 (help@newton.dep.anl.gov), or at Argonne's Educational Programs

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

Argonne National Laboratory