The heat capacity of sodium amide has been determined from 15 to 300°K. in an adiabatically operated calorimeter. At 298.15°K. the heat capacity, entropy and enthalpy were found to be 15.81 cal. deg.-1 mole-1, 18.38 cal. deg.-1 mole-1 and 2841.6 cal. mole-1, respectively.At 240°K. the standard free energy of formation of ammonous amide ion in the h}rpothetical 1 molal ammonia solution is 30.5 kcal. and the partial molal entropy of amide ion is -19.3 cal. deg.-1 mole-1 relative to 5240 [H+(am)[ = 0.0. In comparison with other negative ions the observed entropy of the amide ion in liquid ammonia appears qualitatively correct for a freely rotating ion. For the reaction: XH3(1) = H-(am) + NH»-] = -14.7 cal. deg.-1 mole 1 and K = 2.2 X 10 28 for the ionization of liquid ammonia.

No abstract

No abstract

Vol. 00 gen double bond and a single bond, then each bond would possess 50% double bond character. The interatomic distance found by application of the usual resonance curve is 1.69 Á. The discrepancy between this value and that observed is probably due to the importance of electronic structures in which the oxygen is bonded to the selenium atom by a triple bond. A bond of this type is possible because selenium is not restricted rigorously by the octet rule.The observed sulfur-oxygen distance in sulfur dioxide bears about the same relation to the radii as that found for selenium dioxide, and the two molecules are probably closely similar in electronic structure.The selenium dioxide crystal4 does not contain (4) James D. McCullough, This Journal, 69, 789 (1937).discrete SeOs molecules, but instead consists of infinite chains. The observed Se-0 distances in the crystal, 1.78 Á. and 1.73 Á., have been discussed by McCullough.We are indebted to Dr. James D. McCullough for furnishing us with the sample of selenium dioxide, and to Professor Linus Pauling for his aid and criticism during the course of this investigation. SummaryElectron diffraction photographs of selenium dioxide vapor have been interpreted to lead to the value 1.61 * 0.03 Á. for the Se-0 distance. The value of the angle O-Se-O could not be de crmined.Pasadena, Calif.

No abstract