Trouton's Law - Trouton's Law

This law governs the boiling point of liquids, stating that the ratio of the molar heat of vaporization to the boiling point is almost constant regardless of the liquid, and is equal to 85 (JK ^-1 mol ^-1 ). This ratio corresponds to the entropy of vaporization. This law applies well to liquids with molecular weights of around 100, not very high boiling points, and which are non-associative. However, for liquids with very low boiling points, such as helium and hydrogen, this ratio is much smaller than 85, and for associative liquids, such as water and alcohol, it is greater than 85.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

液体の沸点についての法則で，モル蒸発熱と沸点との比が液体によらずほぼ一定で，85(J K^－1 mol^－1)に等しいという法則．この比は蒸発のエントロピーに対応する．この法則は分子量が100前後で，沸点があまり高くなく，しかも非会合性の液体に対してよく成り立つが，ヘリウム，水素のような非常に沸点の低いものでは，この比は85より非常に小さく，水，アルコールのような会合性のものでは，逆に85より大きい値を示す．

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