October 11, 2024, 10:55:37 PM
Forum Rules: Read This Before Posting


Topic: Consecutive Second Order Reaction Kinetics  (Read 2673 times)

0 Members and 1 Guest are viewing this topic.

Offline eskimogenius

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Consecutive Second Order Reaction Kinetics
« on: March 28, 2015, 10:05:15 PM »
Hi all,

Need assistance solving this consecutive, second order, irreversible reaction in a batch reactor problem.

Initially, 1 mole of A, 2 moles of S. Find mole fraction of X after half of A is consumed. k2/k1 = 2

A + S >k1> X
X + S >k2> Y

Attempted Solution
I formed a system of ODEs for A,Y,S, and X but I don't know where to proceed from here. Furthest I can get is:

Nx' + Ns' = -4 (k1) Nx Ns

Where Ns' = dNs/dt

Offline mjc123

  • Chemist
  • Sr. Member
  • *
  • Posts: 2069
  • Mole Snacks: +302/-12
Re: Consecutive Second Order Reaction Kinetics
« Reply #1 on: March 30, 2015, 07:09:28 AM »
I did it this way:
Define fractions α and β such that
[A] = 1-α
[Y] = β
[X] = α-β
[S ] = 2-α-β
Obtain expressions for dα/dt and dβ/dt. Hence obtain an expression for dβ/dα and solve.
In this way I got (laboriously) β = α2, and the answer to the question follows easily. I can't help thinking that if the solution is that simple there must be an easier way to get to it, but I may be wrong.
It is of course very easy to solve numerically.
« Last Edit: March 30, 2015, 08:32:12 AM by mjc123 »

Sponsored Links