Naked Science Forum

General Science => General Science => Topic started by: neilep on 26/07/2007 21:29:01

Title: Surface Tension
Post by: neilep on 26/07/2007 21:29:01

Surface Tension is well cool...it allows insects and magicians to walk on water.

But what is it ?...and do all liquids have surface tension ?...milk ?...wee wee ?...still cola ?....oil ?..blood ?...chicken soup ?




Remain chilled and don't let your tension surface as you educate the educateable.

Title: Surface Tension
Post by: another_someone on 27/07/2007 00:12:09

The nature of all liquids is that they do have surface tension.  Surface tension is what holds liquids together, and stops them being gases.

Water has particularly strong surface tension, which is why a molecule that is lighter than oxygen, let alone carbon dioxide, can be a liquid at room temperature, while both carbon dioxide and oxygen are gasses at room temperature.

Surface tension is caused by the electrical attraction between molecules of the same substance which holds them together in liquid form.

Title: Surface Tension
Post by: paul.fr on 27/07/2007 08:17:43

http://www.thenakedscientists.com/forum/index.php?topic=6730.msg72880#msg72880

Title: Surface Tension
Post by: eric l on 27/07/2007 08:52:40

"Surface tension" is actually a particular example of "interfacial tension" :  it is the interfacial tension between a liquid and the air.  But you also have interfacial tensions between a liquid and any other surface it is in contact with (glass, plastic...).  Differences between them are the cause of either convex or concave meniscus.
There is a clear relation between surface tension and vapour pressure :  a high vapour pressure meaning low surface tension and vice versa.  Water is a liquid at room temperature because it has a low vapour pressure - at least much lower than carbondioxide or even alcohol.
Interfacial tension is important in many processes.  Offset printing is based on the differences in interfacial tension between the printing plate and ink on one side, and between the printing plate and water on the other.  Because certain zones are treated to change this interfacial tension, they will be wetted by ink while the untreated zones are wetted by water.

Title: Surface Tension
Post by: neilep on 27/07/2007 13:48:43

Thanks You GEORGE, PAUL (Nice experiment) and ERIC,

It is a peculiar thing and I appreciate your helping me to understand it better.

It is interesting to know that specifically in processes like offset printing that it is particularly important.

Thank you ALL again.