Among the chemical reactions having a pronounced thermodynamic driving force to the formation of products, a distinction has to be made between processes which attain a chemical equilibrium state very much shifted towards the products and those where the final equilibrium state corresponds to the truly complete consumption of reactant(s), i.e. where a true chemical equilibrium is actually not attained under the given conditions. Based on a few selected examples, two thermodynamic arguments are led which rationalise the above distinction from different points of view: a phase-rule point of view and a Gibbs energy minimization approach. “Conceptually complete” reactions involve pure phases and, as a consequence, establishing chemical equilibrium would imply a negative variance, what is avoided by the complete consumption of one or more phases. In the Gibbs energy approach, “conceptually complete” reactions and “practically complete” ones can be distinguished (at fixed temperature and pressure) by the different way to attain the minimum Gibbs energy condition, respectively with sharp (not differentiable) and flat (zero derivative) minimum points as a function of the extent of reaction ξ.

中文翻译：

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原则上所有的化学反应都是可逆的吗？“概念上完全”和“实际上完全”反应之间的热力学区别

在对产物的形成具有显着热力学驱动力的化学反应中，必须区分达到化学平衡状态非常向产物转移的过程和最终平衡状态对应于真正完全消耗的过程。反应物，即在给定条件下实际上没有达到真正的化学平衡。基于几个选定的例子，提出了两个热力学论点，从不同的角度合理化上述区别：相位规则的观点和吉布斯能量最小化方法。“概念上完整”的反应涉及纯相，因此，建立化学平衡将意味着负方差，而完全消耗一个或多个相可以避免这种情况。ξ.