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 Phase Boundary, Immiscible Liquids
Name: Stephano
Status: student
Grade: other
Location: LA



Question:
What exactly are we seeing in a phase boundary between immiscible liquids?


Replies:
Stephano,

Picture a common example of a two phase system of immiscible liquids -- oil and vinegar salad dressing. When the bottle has been just sitting for at least several minutes you see the characteristic boundary. The vinegar (a dilute, aqueous solution of acetic acid) is on the bottom. The oil (a hydrocarbon, extremely water-hating -- hydrophobic) on the top. Light in the room passes through each liquid (how else would you see the boundary?). The light does not pass through each liquid at the same rate, and it does not exit at the same angle that it entered. The boundary between the layers results from the difference of the angles of the light exiting the liquids. See Snell's Law in a physics text for a deeper discussion of light in transparent materials.

Warren Young


At the most fundamental level, we see the difference in the speed of light between liquid (1) and liquid (2). This difference forms a meniscus (in the case of a transparent tube) or a "bent" line in the case of an optical path between the two transparent phases, for example a fishing line. This is the most basic observation, however, depending upon the experimental arrangement it may not appear to be "exactly" what we are seeing.

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 (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