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A Simple Computer-Interfaced Calorimeter: Application to the Determination of the Heat of Formation of Magnesium Oxide

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Sze-Shun Wong , Natasha D. Popovich and Shelley J. Coldiron

Department of Chemistry, Iowa State University, Ames, IA 50011

J. Chem. Educ., 2001, 78 (6), p 798

DOI: 10.1021/ed078p798

Publication Date (Web): June 1, 2001

Section:

History, Education, and Documentation

Abstract

This paper describes the design, construction, and laboratory instructional application of a simple computer-controlled, constant-pressure calorimeter. The calorimeter was made using a covered Styrofoam cup as the reaction chamber. A thermistor was used as a temperature-sensing element and was incorporated in a temperature-to-voltage converter circuit based on a bridge amplifier. The instrument was interfaced to a personal computer via an I/O board, and data acquisition software was used to monitor the output voltage of the bridge amplifier. The design and construction of this instrument offer many possible applications of operational amplifiers and related basic electronics theory in chemistry and in interfacing experiments to computers. One application, the determination of the enthalpy of formation of magnesium oxide by applying Hess's law of heat of summation, is demonstrated in this paper. Experimental results for the heat of formation for magnesium oxide were within 1% of the literature value. This experiment also demonstrates the utility and ease of automating temperature measurements for other applications.

Keywords (Audience):

First-Year Undergraduate / General

Keywords (Domain):

Analytical Chemistry

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Calorimetry / Thermochemistry

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This article has been cited by 1 ACS Journal articles (1 most recent appear below).

An Inexpensive Solution Calorimeter
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- An Inexpensive Solution Calorimeter
  Emma Kavanagh , Sam Mindel , Giles Robertson and D. E. Peter Hughes
  Journal of Chemical Education2008 85 (8), 1129
  We describe the construction of a simple solution calorimeter, using a miniature bead thermistor as a temperature-sensing element. This has a response time of a few seconds and made it possible to carry out a thermometric reaction in under a minute, which ...
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