CHED 239 |
| Classical calorimetric methods of analysis and thermal equilibrium experiments are frequently used to determine specific heats of unknown substances. Differential scanning calorimetry (DSC) is a rugged, easy to use instrumental method for thermal analysis and specific heat determinations. DSC has become more routinely used and is finding its way into the chemistry curriculum and has been reported in some physical chemistry, analytical chemistry, and even in some general chemistry courses. The work described herein discusses the use of DSC in a general chemistry laboratory course to determine the specific heats of pure metals and demonstrate the empirical law of Dulong and Petit. The specific heat of seven metals were determined in both a low temperature mode (25oC)and a high temperature mode (150oC)using the DSC. The specific heats of the seven metals were calculated using the Perkin-Elmer Pyris for windows software. The experimental specific heats were compared to the National Institute of Standards and Technology (NIST) values for specific heats calculated using the Shomate equation. The experimentally determined values have an average percent relative error of 1% or less when compared to the NIST values. A constant is calculated based on the empirical law of Dulong and Petit which allows for the calculation of the atomic weight of an unknown metal and its identity. |
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Undergraduate Research Poster Session: Chemical Education
2:30 PM-4:30 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Poster
Division of Chemical Education |