The Free Energy, Heat, and Entropy of Formation of Thorium Tetrafluoride

Technical Report · Sun Feb 14 23:00:00 EST 1960

DOI:https://doi.org/10.2172/4142593· OSTI ID:4142593

Darnell, A. J. ^[1]

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1. North American Aviation, Inc., Canoga Park, CA (United States). Atomics International Div.

The equilibrium constant for the reaction, ThF₄(s) + SiO₂(s) ⇌ ThO₂(s) + SiF₄(g) was determined over the temperature interval 871 to 1077 °K by measuring the equilibrium pressure of SiF₄ above the system. The pressure of SiF₄ from this reaction is given by log P_(atm) = $$\frac{-8200 ± 120}{T (°K)}$$ + 7.740 ± 0.1.30. A heat capacity correction of -2.76 cal/deg-mole gives, for the reaction at 298 °K: ΔF° = 27.9 kcal/mole, ΔH° = 39.4 kcal/mole, and ΔS° = 38 cal/deg-mole. From these calculations and previously published thermodynamic data for SiO₂, ThO₂, and SiF₄ the ΔF°, ΔH°, and ΔS° of formation of ThF₄from the el ements at 298 °K were calculated to be -459.9 kcal/ mole, -482.4 kcal/mole, and -75.8 cal/deg-mole, respectively.

• Research Organization: North American Aviation, Inc., Canoga Park, CA (United States). Atomics International Div.
• Sponsoring Organization: US Atomic Energy Commission (AEC)
• DOE Contract Number: AT(11-1)-GEN-8
• NSA Number: NSA-14-013714
• OSTI ID: 4142593
• Report Number(s): NAA-SR--4924
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL REACTIONS
EQUILIBRIUM
MEASURED VALUES
PRESSURE
REACTION KINETICS
SILICON FLUORIDES
SILICON OXIDES
STABILITY
TEMPERATURE
THERMODYNAMICS
THORIUM FLUORIDES
THORIUM OXIDES