The Molecular Fields of Carbon Dioxide and Nitrous Oxide
The Molecular Fields of Carbon Dioxide and Nitrous Oxide
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二氧化碳和一氧化二氮的分子场
DOI：
10.1098/rspa.1939.0162
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发表时间：
1939
期刊：
影响因子：
--
通讯作者：
T. Ibbs
中科院分区：
文献类型：
--
作者：
R. E. Bastick;H. R. Heath;T. Ibbs
实验表明，在相当大的常温范围内，两种气体的混合物因温度梯度而产生的热分离通常可视为与log （t1 / t2）成正比，t1为热侧的绝对温度，t2为冷侧的绝对温度。因此混合物的总浓度差可以写成Δλ = kt log (t1 / t2)，其中常数kt是热分离系数。kt常数的理论意义是，不同的分子可以被看作是服从逆幂律的排斥力的点中心。在较低的温度下，总趋势是kt随温度逐渐降低。kt实验值的一般表达式可以写成kt = - dλ 1/ d log T = dλ 2/ d log T'，其中λ 1为重气体的比例，λ 2为轻气体的比例，λ 1 + λ 2 = 1。在测量含有二氧化碳的混合物的热分离时发现了一个特点，即kt从低于约145°C的一个确定值变化到高于该温度的一个更高的确定值（Ibbs和Wakeman， 1932）。由此得出结论，二氧化碳分子场的性质发生了变化，从“软”分子变成了“硬”分子，即在145°C以上的行为变得更像一个刚性弹性球体。对二氧化碳粘度的测量支持了这一结论。
Experiments show that the thermal separation produced in a mixture of two gases by a temperature gradient may generally be regarded as proportional to log ( T 1/ T 2) over a considerable range of ordinary temperature, T 1 being the absolute temperature of the hot side and T 2 that of the cold side. Thus the total difference in concentration in the mixture may be written Δλ = kt log ( T 1/ T 2), where the constant kt is the coefficient of thermal separation. The theoretical meaning of the constancy of kt (Chapman 1918) is that the unlike molecules may be regarded as point centres of repulsive force obeying an inverse power law. At lower temperatures there is a general tendency for kt to decrease gradually with temperature. The general expression for the experimental value of kt may be written kt = - dλ 1/ d log T = dλ 2/ d log T' where λ 1 is the proportion of the heavier gas, λ 2 the proportion of lighter gas, and λ 1 + λ 2 = 1. A peculiarity has been found in the measurements of thermal separation in mixtures containing carbon dioxide, in that kt changes from one definite value below about 145° C to a higher definite value above that temperature (Ibbs and Wakeman 1932). This led to the conclusion that there is a change in the nature of the molecular field of carbon dioxide from a “soft” molecule to a “harder” molecule, i.e. the behaviour above 145° C becomes more like that of a rigid elastic sphere. Measurements of the viscosity of carbon dioxide support this conclusion.