Experimental Program - BeO-H20 Reaction
- North American Aviation, Inc., Canoga Park, CA (United States). Atomics International Div.
Although BeO has desirable nuclear and physical properties, it reacts readily with water vapor at temperatures above 1250° C to form a volatile compound. The volatilization rate increases with increasing temperature and is too high to be accounted for by the equilibrium vapor pressure of beryllia alone. Measurements by Grossweiner and Seifert on the effect of temperature and the partial pressure of water on the rate of volatilization of beryllia indicate that the increased volatility results from the reaction BeO(s) + H2O(8) → Be(OH)2(g). From their data at 1400° C, ΔH° = 41.5 kcal/mole and ΔF° = 29 kcal/mole. Hence ΔS° = 7.5 entropy units. No heat capacity data are given, so we shall assume that ΔH° does not vary with temperature; ΔF° at 2000° C, then, is available from the relationship ΔF° = ΔH° - TΔS° and is equal to 24.5 kcal. Since all spontaneous processes taking place at constant temperature and pressure are accompanied by a decrease of free energy, one might hastily conclude from. the large positive value of ΔF° that reaction does not proceed spontaneously. However, the product of the reaction, Be(OH)2 is gaseous and is being constantly removed; this allows the reaction to proceed.
- Research Organization:
- North American Aviation, Inc., Canoga Park, CA (United States). Atomics International Div.
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- OSTI ID:
- 1346553
- Report Number(s):
- NAA-SR-MEMO-1758
- Country of Publication:
- United States
- Language:
- English
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