A Study of Hydrogen Bonding Using Liquid

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 8 Issue 5 (2003) pp 327-329

A Study of Hydrogen Bonding Using Liquid–Vapor Equilibria

Jennifer S. Holt, Rachel Grabow, and Christopher J. Pursell*

Department of Chemistry, Trinity University, San Antonio, TX 78212-7200, cpursell@trinity.edu
Received May 16, 2003. Accepted July 16, 2003.

Published online: 23 August 2003

Abstract. Many undergraduate laboratories use the familiar liquid–vapor equilibrium experiment to demonstrate the Clausius–Clapeyron equation. This paper aims to extend this experiment beyond typical liquid–vapor equilibrium calculations to also explore the hydrogen-bonding capabilities of a series of liquids. By carefully choosing a series of liquids that are very close in molecular weight, but very different in composition (an amine, an alcohol, and a hydrocarbon), students will be able to observe the importance of hydrogen bonding on thermodynamic properties, such as the entropy and enthalpy of vaporization and the normal boiling point of a liquid, and they will be able to verify the assumptions made by Trouton’s rule. Using these chosen liquids, many chemical principles can be explored concurrently with the normal liquid–vapor equilibrium experiment.

Key Words: Laboratories and Demonstrations; physical chemistry; equilibrium; intermolecular forces; thermodynamics; physical properties; phase transitions

(*) Corresponding author. (E-mail: cpursell@trinity.edu)

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Supporting Materials:

Two Excel spreadsheets have been included with this manuscript. One is a representative data set (student data.xls), including the calibration data and the data analysis using the Clausius–Clapeyron equation for each of the liquids chosen. A second worksheet is a template worksheet that students can use to analyze their own data with the appropriate equations and graphs prepared for them (cctemplate.xls). An MS Word document containing a proposed series of questions for the students to consider has been included as a guide for students when writing their laboratory reports (student questions.doc). These files may be downloaded in a Zip file (128 KB) 10.1007/s00897030716a.