Instructions and Experiment on Reversible Reactions and Acid-Base Solutions

Instructions:

1) Open the PhET “Reversible Reactions (Links to an external site.)” simulation if you would like to use Java.  If you would prefer to use the applet in a browser, click this link. (Links to an external site.)

2) Play with the simulation. Try to manipulate all of the possible components!

3) Complete the following:

· Put some number of balls (>50) in one of the wells. In a table, record the number of green and red balls in each well as a function of time. (Suggested time length: 5 minutes, suggested intervals: 15-20 seconds) Paste the table into your document.

· Paste in a graph of your data. Describe the shape of the graph and what it means in terms of the red and green balls. Consider the ratio of red balls to green balls. How does that change over time?

· After some amount of time, this simulation reaches a dynamic equilibrium state. That is, a situation in which components of a system are moving but no net change is observed. Describe how this simulation fits this model in terms of the amount of red and green balls.

B) Investigate - Create your own experiment

Instructions: Investigate, using available tools in the simulation, the effect of a change in temperature on a particular system, Your investigation should include the following factors:

· Purpose

· Hypothesis

· Procedure

· Observations

· Analysis

· Conclusion

Note from me (student): Try to keep the experiment as small as it can possibly be, while fitting in what is needed/expected.

Part 2 - Acid - Base Solutions

1. Take a few minutes to play with the sim.   Check out both the Introduction and Custom Solution tabs. Explore what factors affect pH. List the factors you found that affect pH.

 2.  Select three weak acids from the list that we looked at in class.  For all three of the acids that you selected, solve for the pH of a solution where the initial concentration of the acid is between 3 x 10-3 M and 8 x 10-3 M.  Show your work.  In the simulation, create a custom solution (use the My Solution tab at the bottom of the screen) that shows the equilibrium state for all three of the acids at the concentration and pH that you have selected and calculated.  Take a screen shot and include all three screen shots in your submission.

Here is the list of acids that were looked at in class: https://docdro.id/2xSuvCE