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Combustion Calorimetry with Fluorine: Constant Pressure Flame Calorimetry
Summary
New methods accurately measure reaction heats between fluorine and gases. The heat of formation for hydrogen fluoride (HF) was determined to be -64.4 ± 0.25 kcal/mole using fluorine and ammonia reactions.
Area of Science:
- Thermochemistry
- Fluorine Chemistry
- Chemical Thermodynamics
Background:
- Accurate measurement of reaction enthalpies is crucial for chemical process design and understanding.
- Previous methods for determining the heat of formation of hydrogen fluoride (HF) had limitations.
- Gaseous fluorine reactions present unique challenges due to their high reactivity.
Purpose of the Study:
- To develop and describe novel instruments and methods for measuring reaction heats between fluorine and various gaseous materials.
- To establish a precise method for verifying the extent of reaction for hydrogenous materials.
- To determine the standard heat of formation of hydrogen fluoride (HF) with high accuracy.
Main Methods:
- Development of specialized calorimetric instruments for handling reactive fluorine gas.
- Implementation of methods for precise measurement of gaseous reaction enthalpies.
- Application of techniques to verify the reaction stoichiometry, particularly for hydrogenous compounds.
- Calculation of corrections for non-ideality of hydrogen fluoride.
Main Results:
- Established a measurement system with an estimated accuracy of approximately 0.3 percent.
- Successfully measured heats of reaction between fluorine and several gaseous substances.
- Determined the standard heat of formation of hydrogen fluoride (HF) to be -64.4 ± 0.25 kcal/mole.
- Identified the uncertainty in hydrogen fluoride nonideality corrections as a significant factor affecting precision.
Conclusions:
- The developed instruments and methods provide a reliable means for measuring fluorine reaction enthalpies.
- The determined heat of formation for HF is a valuable thermodynamic datum.
- Further refinement of corrections for hydrogen fluoride nonideality could enhance measurement accuracy.
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