Validity of the Quasi-Stationary-State Approximation in the Case of Two Successive Reversible First-Order Reactions

Viossat, V.; Ben-Aim, R. I.

doi:10.1021/ed075p1165

Cited by 3 publications

(2 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The relationship of zeroth-order reactions and the ratedetermining step is also a concept that students struggle with, as is the whole idea of a zeroth-order reaction, especially when a reactant concentration becomes so high that the order with respect to that reactant becomes zero. 16 Consecutive first-order reactions, 17 leading to the idea of the steady-state approximation 18 and its applications in the simplifying of chemical kinetic systems, are a further challenge for some students. Even more complicated systems, such as enzyme kinetics 19 in more advanced chemical kinetics courses, require a deep understanding of fundamental kinetic principles.…”

Section: ■ Introductionmentioning

confidence: 99%

Smart Worksheets and Their Positive Impact on a Second-Year Chemical Kinetics Course

Shallcross,

Davies-Coleman,

Lloyd

et al. 2024

J. Chem. Educ.

View full text Add to dashboard Cite

Smart Worksheets were introduced in 2017 into a second-year undergraduate chemical kinetics course (UK) and were available to students from the start of the course until the summer examination (ca. 3 months in duration). Several metrics strongly suggest that the introduction of the Smart Worksheets has a very positive impact on student understanding. For example, students who attended workshops completed twice as many questions as in previous years, with some completing them all. Students who attended workshops were much better prepared for these workshop activities, and because students had used the Smart Worksheets before the workshops, the tutor had information on what students understood and did not understand. Therefore, workshop tutors were able to prepare workshops that targeted specific needs. Questions asked in workshops and in an online forum showed more higher-order thinking than in previous years. Student feedback highlighted the usefulness of the Smart Worksheets (e.g., the instant feedback), and examination scores showed a statistically significant difference (95% confidence level) between the mean score for those who used the Smart Worksheets (larger than) compared with those who did not. This study suggests that Smart Worksheets can have a significant positive impact on student cognition, assessment (here examination) performance, enjoyment, and enthusiasm for a highly quantitative course.

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Smart Worksheets and Their Positive Impact on a Second-Year Chemical Kinetics Course

Shallcross,

Davies-Coleman,

Lloyd

et al. 2024

J. Chem. Educ.

View full text Add to dashboard Cite

show abstract

“…[6][7][8][9][10][11][12] Both methods are specific examples of the elimination of a fast variable, also called adiabatic elimination. [13][14][15] Nevertheless QSSA and PEA do not simply consist in eliminating a fast variable from a system of rate equations. The eliminated variable must be either a concentration for QSSA 16 or an extent for PEA.…”

Section: Introductionmentioning

confidence: 99%

Quasi-Steady-State and Partial-Equilibrium Approximations in Chemical Kinetics: One Stage Beyond the Elimination of a Fast Variable

Pellissier-Tanon¹,

Morgado²,

Jullien³

et al. 2021

Preprint

View full text Add to dashboard Cite

<pre>Classical approximations in chemical kinetics, the quasi-steady-state approximation (QSSA) and the partial-equilibrium approximation (PEA), are used to reduce rate equations for the concentrations and the extents of the reaction steps, respectively. We make precise two conditions on the rate constants necessary and sufficient to eliminate a well-chosen variable in the vicinity of a steady state. The first condition expresses that dynamics admits a small characteristic time associated with a fast variable. The second condition ensures that the fast variable is a concentration for QSSA and an extent for PEA. Both approximations exploit the zeroth order of a singular perturbation method. Eliminating a fast variable does not mean that it has reached a steady state. The fast evolution is considered over and the slow evolution of the eliminated variable is governed by the slow variables. The evolution of the slow variables occurs on a slow manifold in the space of the concentrations or the extents. In some cases the dynamics of the slow variables can be associated with a reduced chemical scheme. QSSA and PEA are applied to three chemical schemes associated with linear and nonlinear dynamics. We find that QSSA cannot be identified with the elimination of a reactive intermediate. The nonlinearities of the rate equations induce a more complex behavior.</pre>

show abstract

Reduction of Large Detailed Kinetic Mechanisms: Application to Kerosene/Air Combustion

Luche

Reuillon

Boettner

et al. 2004

Combustion Science and Technology

View full text Add to dashboard Cite

Validity of the Quasi-Stationary-State Approximation in the Case of Two Successive Reversible First-Order Reactions

Cited by 3 publications

References 16 publications

Smart Worksheets and Their Positive Impact on a Second-Year Chemical Kinetics Course

Smart Worksheets and Their Positive Impact on a Second-Year Chemical Kinetics Course

Quasi-Steady-State and Partial-Equilibrium Approximations in Chemical Kinetics: One Stage Beyond the Elimination of a Fast Variable

Reduction of Large Detailed Kinetic Mechanisms: Application to Kerosene/Air Combustion

Contact Info

Product

Resources

About