大学化学 >> 2021, Vol. 36 >> Issue (2): 2002076.doi: 10.3866/PKU.DXHX202002076

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平衡近似和稳态近似使用条件浅析

孙莹, 张树永()   

  • 收稿日期:2020-02-27 录用日期:2020-04-08 发布日期:2020-04-16
  • 通讯作者: 张树永 E-mail:syzhang@sdu.edu.cn
  • 作者简介:张树永, Email: syzhang@sdu.edu.cn

Analysis on the Application Conditions of the Pre-Equilibrium and Steady-State Approximations

Ying Sun, Shuyong Zhang()   

  • Received:2020-02-27 Accepted:2020-04-08 Published:2020-04-16
  • Contact: Shuyong Zhang E-mail:syzhang@sdu.edu.cn

摘要:

对化学动力学中经常使用的平衡近似和稳态近似的使用条件进行了讨论。从对峙反应达到和维持平衡的角度,给出了平衡近似使用的条件,指出了原条件的不足之处。对于连续反应,采用定义无量纲量和作图的方法,进一步明确了采用稳态近似的条件是中间体消耗速率常数(k2)比生成速率常数(k1)大100倍,即k2>100k1。此时采用稳态近似处理的误差小于1%。

关键词: 近似处理, 平衡近似, 稳态近似, 连续反应, 作图法

Abstract:

The application conditions of pre-equilibrium and steady-state approximations usually used for treatment of complex chemical kinetics are discussed. Based on the characters of opposing reaction, the simplified application conditions for pre-equilibrium approximation is proposed. The shortcoming of the former conditions is pointed out. By defining a dimensionless parameter relating to the discrepancy from steady state and using graphic method, the application conditions of steady-state approximation for the consecutive reaction is clarified. When the rate for consumption of the intermediate is 100 times larger than its generation rate, the error by using steady-state approximation is less than 1%, which is a good approximation.

Key words: Approximation treatment, Pre-equilibrium approximation, Steady-state approximation, Consecutive reaction, Graphic method

MSC2000: 

  • G64