Some Thermodynamic Properties of the H1H2, H2H2 Molecules and Compounds Containing the H2 Atom

The summations of state and free energies of the molecules H21, H22 and H1H2 have been calculated at temperatures from 20.4 to 700°K and their dependence on the spin and statistics of H2 discussed and illustrated. The equilibrium constants of the reaction H21+H22 = 2 H1H2 are found to deviate markedly from the value 4 expected from simple probability considerations. The equilibrium constants of the reactions H21+2 H2Cl⇄H22+2 H1Cl and H21+2 H2I→H22+2 H1I have been calculated and found to be appreciably different from unity, showing that appreciable differences in equilibrium constants of chemical reactions may be expected depending on which isotope of hydrogen enters into the reaction. Small differences in the electrode potentials of the two hydrogen isotopes may be expected but no exact estimates have been made.