Experiment: Chemical Equilibrium


    The JAVA applet below simulates the gaseous reaction

2 A     —›     B

in a closed container. Select the initial number of A molecules ( 80 ) or the initial number of B molecules (40 ) and the temperature (298 or 380 K or the value "Low"). Click the "Start" button to begin the simulation and the "Stop" button to end it. The A molecule is symbolically represented by a red ball. A blue ball depicts the B molecule. When the "On" button is clicked, plots of the number of A and the number of B molecules versus time are displayed along with the animation.

    Use the applet to perform the following exercises and answer the questions.

  1. Select 80 molecules of A and a temperature of "Low." Click the "Start" button and observe the animation for a couple minutes. Describe what you observed.
  2. Select 80 molecules of A and a temperature of 298 K. Click the "On" button and observe the animation for three minutes. Record the value of Kc at three minutes. How did the number of A molecules and the number of B molecules change with time?
  3. Select 40 molecules of B and a temperature of 298 K. Click the "On" button and observe the animation for three minutes. Record the value of Kc at three minutes. How are the plots of the number of A molecules and number of B molecules versus time in this exercise different from the plots in the previous (#2) exercise? In what way are the plots in the two exercises (#2 and #3 ) similar?
  4. What evidence do you have to support the assertion that the equilibrium states in exercises #2 and #3 are effectively the same?
  5. Select 80 molecules of A and a temperature of 380 K. Click the "On" button and observe the animation for three minutes. Record the value of Kc at three minutes. How does the equilibrium state at 380 K in this exercise differ from the equilibrium state at 298 K in exercise #2?

    If you have preformed all of the experiments, answered all of the questions, and completed the report to be submitted for credit, then you may check the Answers to Chemical Equilibrium Questions



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Dr. Nutt's CHE 115 Course