PhET: Equilibrium Part 1
Name: Melina Ramirez Period: 6 
Exploration:
Go to this PhET.
We will use this simulation to help us understand equilibrium and reversible reactions. 
Start by playing around with the simulation. Press all the buttons, move all of the levers, etc.
When you are done, press the green reset button on the far right.
Tips:
You will be making predictions before many of the steps in this activity.
Make sure to make your best guess before performing the steps.
Once you have made a change to the PhET, you will need to wait until the number of molecules on each side reaches the point where they are staying in about the same range. This will often take a couple of minutes.
This DOES NOT mean that the number of molecules on Side A and Side B will be the same, but rather that the number of molecules on Side A is staying about the same and the number of molecules on Side B is staying about the same.
Because the molecules will always be moving, the number of molecules will continue to change. 
Press the green reset button on the far right. 
Adjust both gray platforms so they are as far down as they can go. 
You can do this by clicking and dragging the platforms. 
In a moment, you will add 100 molecules to the Side A. What do you think will happen to the molecules over time?
Once the simulation has had time to adjust, how many molecules do you think there will be on each side?
Add 100 molecules to Side A.
This can be done most easily by typing in ‘100’ to the text box in the upper right corner next to the green ‘A’.
Wait for the simulation to adjust.
Hint: The simulation will adjust more quickly if you turn up the heat.
What happened to the molecules you put on ‘Side A’?
When the simulation has had time to adjust, about how many molecules are on each side?
Once the simulation has adjusted, do the molecules continue to move back and forth?
If so, how does the number of molecules on each side stay about the same?
Will all of the molecules ever move back to their original position, with all 100 on Side A?
Why or why not?
What does this simulation help us visualize about what direction a reaction can go?
Do you think all reactions can go in both directions?
Why or why not?
What do you think would have happened if I would have started with 200 molecules on Side A?
Explain your answer.
What do you think will happen if you add 50 more molecules to Side B?
Why?
Add 50 more molecules to Side B.
You can do this by pressing the ‘up’ arrow next to the Side B text box on the upper right 50 times.
Wait for the simulation to adjust. 
What happened when you added these new molecules?
About how many are on each side?
How does this compare to your prediction?
Why do you think this happened?
What do you think would happen now if you added 50 more molecules to Side A?
Why?
What do you think would happen if I removed molecules from Side A?
Why?
Remove 50 molecules from Side A.
You can do this by pressing the ‘down’ arrow next to the Side A text box on the upper right 50 times.
Wait for the simulation to adjust.
What happened when you removed these molecules?
About how many are on each side?
How does this compare to your prediction?
Why do you think this happened?
Keeping in mind what you just learned, complete the following statements by highlighting the words that make the statements correct.
After adding molecules to Side A, the number of molecules on Side B will begin to increase / decrease (select one).
After removing molecules from Side A, the number of molecules on Side B will begin to increase / decrease (select one).
After adding molecules to Side B, the number of molecules on Side A will begin to increase / decrease (select one).
After removing molecules from Side B, the number of molecules on Side A will begin to increase / decrease (select one).