University Chemistry ›› 2021, Vol. 36 ›› Issue (2): 2002076.doi: 10.3866/PKU.DXHX202002076

• Between Teacher and Student • Previous Articles     Next Articles

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

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