2 replies to this topic

[Art Montemayor]

Mac:

Find or obtain a copy of:

"The Properties of Gases and Liquids"
by Robert Reid and Thomas Sherwood
McGraw-Hill Book Company

My copy is the 2nd Edition (1966) and on p. 387 to 391, you'll find the section called Surface Tensions of Aqueous Solutions. There, the authors explain that whereas for nonaqueous solutions the mixture often approximates a linear dependence with mole fraction, aqueous solutions show pronounced non-linear characteristics.

For binary mixtures of highly polar materials, the method of Tamura et al. can be used with expected approximate success.

I hope this information helps out.

Art Montemayor
Spring, TX

[MrShorty]

I checked through that book yesterday, and the section focuses on surface tensions of aqueous-organic systems, with very little mention of aqueous-electrolyte systems. It may not matter, but it seems that you can rarely assume that an electrolyte behaves the same as a "normal" molecule.

Found this using google: http://www.gewater.c...ilicity_and.jsp Claims that the surface tension of a 5.7% NaOH sol'n is 76 where that of pure water is 73 dynes/cm. I'm not sure how accurate you would be upon extrapolation.

I recall locating books dedicated to surface chemistry and similar phenomena at the local university library.

If your need for the surface tension warranted such a move, it shouldn't be too hard to set up the experiment and measure the surface tension of that sol'n, or pay a testing lab with a tensiometer to do it.