JCE Online Journal of Chemical Education
 | Subscriptions  | Software Orders  | Support  | Contributors  | Advertisers  | 

JCE Print
   Current Issue
 Previous Issues
 Supplements
 Search JCE Index

JCE Digital Library
   DigiDemos
 QBank
 SymMath
 WebWare

JCE Software
   Latest Releases
 Software & Video
 Downloads
 Support

Only@JCE Online
   JCE Online Store
 JCE HS CLIC
 JCE Discussion Forums
   Biographical Snapshots
 ChemEd Resource Shelf
 Featured Molecules
 Hal's Picks
 Project Chemlab
 Reviewed WWW Sites
 "Web-Ed" Articles

About JCE
   Features
 Publications
 Operations
 Outreach
 Contact Us


  Home > JCE Print > Journal of Chemical Education > Issues > 1999  > March  >
Research: Science and Education
Regression Methods To Extract Partial Molar Volume Values in the Method of Intercepts
Leon F. Loucks
University of Prince Edward Island, Chemistry Department, Charlottetown, Prince Edward Island C1A 4P3, CANADA
Cover
March 1999
Vol. 76 No. 3
p. 425
Abstract
Partial molar volumes of the components of binary solutions have been traditionally evaluated by "the slope method" or by "the method of intercepts". The latter, founded on the relationship VM = VM1 + (VM2 - VM1)x2 (where VM is molar volume) relies on the relatively imprecise graphical assignment of tangents to the curved plot of VM as a function of the mole fraction of one component, x2. The intercepts of the tangent with the left and right axes give the partial molar volumes, VM1 and VM2, of components 1 and 2. Molar volume data can now be readily analyzed by regression techniques of spreadsheet software to generate an equation that fits the data well and includes the curvature in the plot of VM against mole fraction. The inclusion of a parabolic term centered on x2= 0.5 is especially helpful. Thus, VM = a + bx2 + c(x2 - 0.5)2 has been used. The coefficients a, b, and c, once evaluated for the dependence of VM on x2, are then used to determine the first derivative, which is the slope of the tangent line at any x2 value; that is: dVM/dx2 = b - c + 2cx2. Hence the intercepts of the tangent line can be determined as VM1 = a + 0.25c - cx22; VM2 = a + b - 0.75c + 2cx2 - cx22. This method has been applied to the binary system of ethanol-ethylene glycol and data are provided for the t-amyl alcohol-toluene system. This method of analysis is much more precise than graphical methods and it extends the laboratory experiment to utilize modern computer techniques.
More Information
*  Citation
 Loucks, Leon F. J. Chem. Educ. 1999 76 425.
*  Keywords
 Physical Chemistry; Thermodynamics; Laboratory Computing / Interfacing; Solutions / Solvents; Intermolecular Forces
*  History
 Created:
Last Updated:		 June 15, 1999
June 22, 2005
<< Previous Article Table of Contents Next Article >>
  Home > JCE Print > Journal of Chemical Education > Issues > 1999 > March > Page 425


Subscriptions
 Subscription Info
 Order Forms

JCE HS CLIC

Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
 JCE HS CLIC

Contributions Welcome
JCE welcomes your submission
 Contributors' Corner

Advertisers
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
 Recent Advertisers

Be An Ambassador
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.
 Outreach with JCE

Comments to
jceonline@chem.wisc.edu		 Copyright © Division of Chemical Education, Inc., American Chemical Society.
All rights reserved.