Halpern Arthur M
Department of Chemistry and Physics, Indiana State University, Terre Haute, Indiana47809, United States.
J Phys Chem A. 2021 Oct 21;125(41):9071-9076. doi: 10.1021/acs.jpca.1c05996. Epub 2021 Oct 12.
A new equation of state (EOS) for helium-4 is used to obtain the equilibrium thermochemical properties of helium-4 dimerization (2He ⇌ He) and trimerization (3He ⇌ He) between 3.0 and 10.0 K. It is shown that at sufficiently low temperatures there are appreciable populations of dimer and trimer. The calculations account only for monomer, dimer, and trimer. At 3.0 K, the respective values for dimerization and trimerization are 0.4832 and 0.4876, respectively. The standard enthalpy changes at 3.0 K are -54.53 and -110.0 J/mol, and standard entropy changes are -24.22 and -42.97 J/mol-K. Statistical thermodynamic calculations provide results that are qualitatively consistent with those obtained from the EOS calculations.
一种新的氦 - 4状态方程（EOS）被用于获取3.0至10.0 K之间氦 - 4二聚化（2He ⇌ He）和三聚化（3He ⇌ He）的平衡热化学性质。结果表明，在足够低的温度下，二聚体和三聚体有相当数量的存在。计算仅考虑单体、二聚体和三聚体。在3.0 K时，二聚化和三聚化的各自值分别为0.4832和0.4876。3.0 K时的标准焓变分别为 - 54.53和 - 110.0 J/mol，标准熵变分别为 - 24.22和 - 42.97 J/mol - K。统计热力学计算提供的结果在定性上与从EOS计算获得的结果一致。
