Portal de Periódicos da CAPES

Heat and free energy of formation of deuterium oxide

1940; US government; Volume: 24; Issue: 4 Linguagem: Inglês

10.6028/jres.024.020

2376-5305

Frederick D. Rossini, John W. Knowlton, H.L. Johnston,

Hydrogen Storage and Materials

Calorimetric measurements of the ratio of the heat evolved in the formation of 1 mole of liquid deuterium oxide, from gaseous deuterium and ordinary oxygen, to the heat evolved in the formation of 1 mole of ordinary liquid water, from gaseous ordinary hydrogen and oxygen, yielded the value 1.030 68 ± 0.000 29 for 25° C and a constant pressure of 1 atmosphere.Calorimetric measurements of the ratio of the heat of vaporization of 1 mole of deuterium oxide to that of 1 mole of ordinary water yielded the value 1.031 45 ± 0.00075 for 25° C and zero pressure.Combination of these with other data yielded the following thermodynamic values: D.(g) + 1/2 O.(g) = D.O(liq), c.Ho",.u= -294,563 ± 94 into j/mole (-70,414.0± 22.5 cal/mole), c.FO,g8.l.= -243,470 ± 100 into j/mole (-58,200.5 ± 23.9 cal/mole) ; D,O(liq)=D.O(g), c.Ho",.u=45,391 ±36 into j/mole (10,850.5 ±8.6 cal/moleh c.Fo208.I.=8,949 ± 9 into j/mole (2 139.2 ± 2.2 cal/mole); D,(g)+1/2 O,(g)=D,O(g) , c.H 6 ", ... = -249, 172 ±100 into j/mole (-59,563.5±23.9 cal/mole), c.Fo",.,,=-234,521 ±100 into j/mole (-56,061.2±23.9 cal/mole), AHoo=-246,231 ±100 into j/mole (-58,860.5±23.9 cal/mole); D.(g) +H~O(liq) = HHg) +D,O(liq), AW"'16 = -8,770± 83 into j/mole (-2,096.4 ± 19.8 cal/mole), C.r"U6= -6,316 ± 96 into j/mole (-1,509.8 ± 22.9 cal/mole); D,(g) +H~O(g)=HHg)+D,O(g), AHO,g8.1.=-7,386±90 into j/mole (-1,765.6 ±21.5 cal/mole), C.FO ",.16=-5 ,966 ±90 into j/mole ( -1,426.1 ±21.5 cal/mole), AHoo=-7,337 ±90 into j/mole (-1,753.9±21.5 cal/mole); D,O(liq), 8°108 ... = 76.099±0.130 into j/degree mole (18.191 ± 0.031 cal/degree mole).On the assumption that the bond energies in H~ and D, are the same, and likewise in H~O and D20, the difference in the zero-point energies of H~O(g) and D20(g) was calculated to be 14,841 ± 91 into j/mole (3,548 ± 22 cal/mole, or 1,243.0± 7.6 wave numbers).The accord of this value with that recently calculated by Darling and Dennison from the vibrational-rotational spectra of deuterium oxide and protium oxide, 1,245.5 ± 2.0 wave numbers, indicates that, within the assigned limits of uncertainty, the respective bond energies are independent of the mass of the nucleus of the atom .I. Introduction ___________________ _ .______ ________________________ 370 II.