Lesson 6. Lesson 6 - Modeling Liquids and Evaporation

Umit Aslan, Umit Aslan, Royi Lachmy, Umit Aslan
Chemistry
N/A
Introductory High School Chemistry
v1

Overview

Will be updated.

 

 

 

Standards

Computational Thinking in STEM
  • Computational Problem Solving Practices
    • Developing Modular Computational Solutions

Acknowledgement

Cite the Modelsim research

Activities

  • 1. Purpose
  • 2. Exploration 1- Experiment and Observations
  • 3. Exploration 1- Observations 2
  • 4. Exploration 2 - Brainstorming
  • 5. Exploration 2 - Predict
  • 6. Exploration 2 - Procedure
  • 7. Exploration 2 - Experiment and Observation
  • 8. Exploration 3 - Procedure
  • 9. Follow up

Student Directions and Resources


In the last activity you explored how pressure and temperature might impact the gas inside of a closed container. As part of this unit, you also attempted to replicate the behavior of a steam piston in your syringe sandbox model. However, we did not consider the role of water in this model (as steam is heated water). In an earlier activity, you also explored how an odor travels through a room. However, we did not consider that the odor came from peppermint oil, a liquid.

Purpose: How do substances change from one state to another?

 

 

 

1. Purpose


Consider the question of how substances change from one state to another.


Question 1.1

How does a substance change from a liquid to a gas or from a gas to a liquid?



Question 1.2

Consider what other factors might cause particles to "clump" together like they do in a liquid?



Question 1.3

Gravity may have an effect on whether or not particles act like a gas or liquid.  Think about your previous work with particle sandbox models. How could we add gravity to those models?

2. Exploration 1- Experiment and Observations


  1. Press SETUP, and then GO/PAUSE/ADD ELEMENTS to run the model.
  2. Be sure to set the "gravity-on?" and/or "use-graph-for-gravity" switches to "on."
  3. To change the forces on the particles, click the DRAW GRAVITY VS HEIGHT GRAPH button and then draw a new graph by clicking and dragging in the graph side of the view.
  4. Experiment with different graphs to see how particles behave. For example, think about whether or not gravity is the same throughout the container.
  5. Once you've made a graph you're happy with, use the "SAVE" button to save to your machine so that the rest of your classmates can see it.

 

While conducting the experiment described in the previous steps, answer the questions below:


Question 2.1

1.  Record the observations you made during the virtual experiment.



Question 2.2

2.  How did the movement of the particles in this model compare to the movement of particles in previous activities?



Question 2.3

3.  How did the graph you drew of gravity compare to the graph made by your classmates?



Question 2.4

4.  Did the graph you made cause the particles to act like a liquid?

3. Exploration 1- Observations 2


In reality, gravity is essentially the same throughout the room or a given container.  For that reason, we should use a constant amount of gravity despite the height of the particles.  Try drawing in a constant value for gravity and observing the particles.


Question 3.1

When gravity is set to a constant, do particles behave as if they are a liquid? Describe their behavior and any observations you made during the experiment below.

4. Exploration 2 - Brainstorming


Watch the video below:


Question 4.1

How does a substance change from a liquid to a gas or from a gas to a liquid?



Question 4.2

Consider the video above that shows alcohol evaporating. What do you think happens in the container with water? Would it act the same as alcohol and nail polish?

5. Exploration 2 - Predict


Now watch the video again.


Question 5.1

Why do you think water evaporates differently than alcohol?  What other forces might be acting on the particles in a liquid?

6. Exploration 2 - Procedure


  1. Press SETUP, and then GO/PAUSE to run the model.
  2. You can use the attractive and repulsive force graph on the right side of the model to change the way the particles interact with one another.
  3. Set the MOUSE INTERACTION drop down menu to "add green particles" add some more green particles to the view.
  4. To change the intermolecular forces between particles, click the DRAW GRAPH button and then draw a new graph by clicking and dragging in the graph side of the view.
  5. Experiment with different graphs to see how particles behave.
  6. When you've found a graph that you like, save your model with the SAVE button.

 


Question 6.1

Sketch a graph of the intermolecular forces that you think exist for water.

Note: Draw your sketch in the sketchpad below


Question 6.2

How do you think this graph compares to the graph of intermolecular forces for the alcohol from the video?

7. Exploration 2 - Experiment and Observation


  1. Press SETUP, and then GO/PAUSE to run the model.
  2. Set the "MOUSE-INTERACTION" chooser to anything that isn't "none - let particles move"
  3. Set MOUSE INTERACTION to "add green particles." Add green particles throughout the space on the left.
  4. Set MOUSE INTERACTION to "add purple particles." Add purple particles to the bottom fourth of the space on the left.
  5. Make sure the "gravity-on?" switch is set to "on."
  6. To change the intermolecular forces between particles, click the DRAW GRAPH button and then draw a new graph by clicking and dragging in the graph side of the view. Then set the "attractive-forces-from-graph" switch to "on."
  7. Try replicating the graph on the right.
  8. When you're ready, switch the MOUSE-INTERACTION chooser to "none - let particles move"
  9. Observe the model for a while. Record your observations on the following step.

 

 

While conducting the experiment described in the previous step, answer the questions below:


Question 7.1

Record the observations you made during the virtual experiment.



Question 7.2

How did the movement of the particles in this model compare to the movement of particles in previous activities?



Question 7.3

The graph used in this model is similar to a graph of the attractive and repulsive forces in water. Now, your teacher will do a demonstration that shows these forces in alcohol. Would you expect a graph of the alcohol used in the teacher demonstration to be the same? Describe what you think that graph would look like and why. 

8. Exploration 3 - Procedure


Using the same model, try to replicate what you watched in the video with alcohol and nail polish.


Question 8.1

Record your observations below

9. Follow up


Now that we've completed a number of explorations about how forces such as gravity, as well as forces between particles change the way particles behave, answer the questions below:


Question 9.1

While water didn't evaporate quickly when it was placed on the table, how might we speed up this process? Be sure to explain your answer from a particle perspective!



Question 9.2

What would happen if we placed a fan so that it continually blew air over the puddle of water on the table. How would this impact evaporation? How would this change the way the particles interacted?



Question 9.3

What would happen if the puddle of water was on a hot plate that was slowly increasing in temperature. How would this impact evaporation? How would this change the way the particles interacted?



Question 9.4

If we wanted to keep the water from evaporating, what are some ways we could accomplish this? Be sure to explain your answer from a particle perspective!