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
   JCEDLib Catalogue
   ChemInfo
 Data-Driven Exercises
 DigiDemos
 Featured Molecules
 LivTexts
 LrnCom
 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 > 1998  > January  >
Information • Textbooks • Media • Resources
The Real Reason Why Oil and Water Don't Mix
Todd P. Silverstein
Willamette University, Chemistry Department, 900 State Street, Salem, OR 97301-3922
Cover
January 1998
Vol. 75 No. 1
p. 116
Abstract
The majority of introductory chemistry and organic chemistry textbooks state that oil and water don't mix because of enthalpic effects. These texts generally make the argument that the mixing process is endothermic, reasoning that the water-water hydrogen bonds that must be broken in order to accommodate the solute are much stronger than the subsequent solvent-solute dipole-induced dipole intermolecular forces that are formed. In fact, in most cases the mixing process is exothermic, so the immiscibility of the two liquids must be explained by a loss of entropy in the system. The widely accepted model explaining the hydrophobic effect invokes the formation of icelike clathrate hydrate "cages" around nonpolar solute molecules. Water molecules at the surface of these relatively rigid clathrate structures are strongly hydrogen-bonded to one another. The formation of these solvent "cages" explains why both Delta H and Delta S are negative for the solution process, and the endergonicity of solvation is thus due to entropy and not enthalpy. Authors should remove from their textbooks the incorrect enthalpic/hydrogen-bond explanation for the hydrophobic effect. Because aspects of the correct entropic/clathrate "cage" explanation lie beyond the scope of introductory or organic chemistry courses, it may be wisest to omit any detailed physical explanation of the "like dissolves like" phenomenon. If the overall format of the text permits, a brief discussion of solvation entropy effects might be included in the section dealing with the immiscibility of oil and water
More Information
*  Citation
 Silverstein, Todd P. J. Chem. Educ. 1998 75 116.
*  Keywords
 Introductory/High School Chemistry, Physical/Theoretical, and Biochemistry
*  History
 Created:
Last Updated:		 June 28, 1999
June 23, 2005
<< Previous Article Table of Contents Next Article >>
  Home > JCE Print > Journal of Chemical Education > Issues > 1998 > January > Page 116



Chemistry Teacher Connection

The "Chemistry Teacher Connection" (CTC) is especially for high school chemistry teachers. For only $40/year, it offers an online-only subscription to CLIC along with membership in the Division of Chemical Education, normally $65/year. CTC subscribers receive access to all articles and supplements from 1996 through the current issue.
More About CTC
Order the Chemistry Teacher Connection

C&EN CLICs

Through special arrangement with the ACS, JCE High School CLIC is now able to provide subscribers with online access to Chemical & Engineering News articles that have been selected specifically for secondary science instructors and their students. 
 C&EN CLICs

JCE Collections Available
Occasionally, collections of JCE back issues become available for donation to individual teachers, schools, or libraries. JCE matches collections with interested recipients. Recipients pay shipping costs or pick up the collection.
 List of available collections

Contributions Welcome
JCE welcomes your submission
 Contributors's Corner

Subscriptions
 Subscription Info
 Order Forms

Fishing for New Ideas
Always in the
process of
improving, CLIC
welcomes ideas and comments.

Email Us

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