Sodium hydride dissolves in and reacts with molten NaOH to give an equilibrium mixture of NaH, NaOH, Na/sub 2/O, Na, and H. In the case where there is a gaseous phase (hydrogen) and only one condensed phase, the system is defined by the temperature, pressure, and one composition variable. The equilibrium, H/ sub 2/ pressure, which is a measure of the H/sub 2/ activity within the melt, was determined as a function of the composition of the condensed phase(s) at 600, 700, and 500 deg for equilibrium mixtures with original compositions of 2.5 to 97.5, 5.0 to 95.0, l0.0 to 90.0, and 20.0 to 50.0 mole% NaH-NaOH. The equilibrium H/sub 2/ pressure-composition isotherms obtained by removing measured increments of H/sub 2/ were reproduced by reabsorbing H/sub 2/. Results for the 5.0 mole % NaH mixture were duplicated by starting with an equivalent quantity of either Na in NaOH or Na/sub 2/O in NaOH, and reacting with measured increments of H/sub 2/. The system is discussed in relation to the interdependent reactions involved, the phase rule, the thermodynamics of certain reactions, and experimental techniques employed. (auth)

Portions of the NaOH-NaH phase diagram were studied by means of differential thermal analysis. Under certain conditions NaH will either react with NaOH according to the equation NaH + NaOH in equilibrium Na/sub 2/O + H/ sub 2/ or thermally dissociate according to the equation NaH in equilibrium Na + 1/2 H/sub 2/. Both of these reactions are suppressed by a high H/sub 2/ pressure; and NaH neither reacts nor dissociates to an extent sufficient to affect the results reported. This was evidenced by the fact that changing the H/ sub 2/ pressure above the system in the range indicated did not change, within the limit of error of the experiments ( approximately plus or minus 5 deg ), the temperature at which a phase change was started or completed. Therefore the concentrations of Na and Na/sub 2/O present in the samples must have been small in all cases. Under a high H/sub 2/ pressure, therefore, the system may be considered as essentially binary, consisting of NaOH and NaH. (auth)

A 4-ft-7-in. adsorption column packed with 1/8 in. sodium fluoride pellets was designed to reduce the hydrogen fluoride content of the fluorine being used by the Volatility Pilot Plant from 5% to less than 0.01%. It will be a non-isothermal packed bed with the bas inlet heated to 100 C to avoid plugging and the exit cooed to 25 C for more complete HF removal.