Class 4

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The Bodenstein Steady-State Approximation

Class 4 examines the use of the Bodenstein steady-state approximation for generating mechanistic rate expressions. It explains the relationship between the rate of mechanistic steps and the apparent rate of non-elementary reactions. Apparent rate coefficients and limiting forms of rate expressions are introduced.

Learning Outcomes

After completing Class 4 you should…

  • Know
    • the definition of a reactive intermediate, kinetically insignificant step, effectively irreversible step, apparent rate coefficient, and limiting form of a rate expression
    • the defining equations for the net rate of generation of a species in terms of the rates of mechanistic steps, and the Bodenstein steady-state approximation
  • Understand
    • mechanistic steps are elementary reactions
    • there must be a linear combination of the mechanistic steps that equals the apparent, non-elementary reaction
    • mechanistic steps must be reversible, but the reverse rate may be negligibly small
  • Be able to
    • write an expression for the rate of generation of a reactant or product of a non-elementary reaction in terms of its rates of generation in the steps of the reaction’s mechanism
    • simplify rate expressions for kinetically insignificant and effectively irreversible steps
    • identify reactive intermediates
    • write Bodenstein steady-state approximation for a reactive intermediate
    • eliminate concentrations of reactive intermediates from mechanistic rate expressions using the Bodenstein steady-state approximation
    • define the minimum number of apparent rate coefficients in a mechanistic rate expression
    • generate limiting forms of mechanistic rate expressions

Prepare

  • Read Sections 4.1 - 4.3 and 4.6 and Example 4.8.1 from Chapter 4 of REB, The Book
  • Watch the Class 4 Preparation Video

Participate

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Practice

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