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Chemistry

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Analytical Chemistry

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Chemical Equilibria

Chemical Potential in Solution Activity

Description

Chemical potential and activity describe how a species behaves in a solution. Activity is the effective concentration of a species. It accounts for the electrolytes near that species and depends on the ionic strength of the solution.

Activity is calculated as molar concentration multiplied by the...

Transcript

一种物质的活度是其有效浓度的度量,同时考虑了其他因素,例如电解质对化学平衡的影响。

因此,热力学平衡常数用活度表示比用浓度表示更为准确。

活性可以表示为该物种的摩尔浓度与其活度系数的乘积。

活度在形式上是根据化学势定义的,化学势也称为偏摩尔吉布斯能,即在给定温度、压力和组成条件下,系统吉布斯能随某物种每摩尔变化所发生的变化量。

请记住,吉布斯能同时受熵和焓的影响,而热力学上有利的反应其吉布斯能变化为负值。

随着混合物组成的改变,其偏摩尔吉布斯能也随之变化。因此,活度反映了影响反应有利性的与组成相关的性质,例如离子强度。