ChE 344
Problem Set 3
Due Tuesday, January 15, 2008 (Lecture 4)
Group Assignment

 

  1. PLQ3 - Each group member is to individually define θi, θA, θB, and δ and then send to CTools before 9:10 a.m.
  2. P2-12B
  3. P3-6B
  4. P3-10 (a) and (b)
  5. Write a paragraph describing activation energy, its origin, and how it affects chemical reaction rates.
  6. Go to the website: http://www.chem.uci.edu/undergrad/applets/sim/simulation.htm. Note: make sure your browser suports Java.
    When you access the website, you should see something very similar to this:

    The reaction is
    (A + B ↔ C + D)
    Red + Yellow ↔ Green + Blue

    In the upper left-hand corner of the screen should be a box, which is the “simulation control panel”. The numbers in the boxes next to red/yellow/green/blue represent the initial number of molecules (i.e. initial concentration or number density) present in the simulation. The values k_f and k_r are the forward and reverse reaction rate constants respectively. These are expressed as a probability between 0 and 1 that a collision between reactants will result in a reaction. The “Stripchart ON” button allows you to track changes in the number of molecules over time. Detailed instructions for operating the simulation are available by clicking on the link displayed above the graphic.
    (a) Run a simulation with k_f = k_r, and beginning with equal numbers of red and yellow balls. Track the changes in numbers of molecules using the stripchart. What is observed? Now run the simulation again in the cases when k_f > k_r and k_f < k_r. How do these simulations differ from the original case?
    (b) How does the time to reach equilibrium change when you increase the number of red and yellow balls? Why?
    (c) How does the time to reach equilibrium change when kf and kr are increased? Why?
    (d) Once equilibrium is reached are reactions taking place? What does this result say about chemical equilibrium?
    (e) Describe what happens when the number of red balls does not equal the number of yellow balls initially.
    (f) What is the most important thing you learned from running the simulation