Activity 6

Activity 6: States of Matter and Intermolecular Forces



To begin this activity, review the Content Slides in D2L on States of Matter and Intermolecular Forces. We are all familiar with the states of matter (solids, liquids and gases) for many substances. In the First Activity we explored these states of matter for water. In Activity 6, we would like to take our overall understanding of states of matter to the molecular level. We will use the States of Matter simulation at http://phet.colorado.edu/ . There are two key characteristics of molecules that determine their state of matter. The first one is the temperature of the matter, and the second one is the intermolecular forces (how well atoms/molecules stick to one another) between atoms and molecules.

One of the first things to think about here is temperature. Temperature and thermometers have a very similar relation to speed and speedometers. For all practical purposes, a thermometer is really a speedometer for molecular speed or motion. At this site (another good NSF funded science education site)http://www.visionlearning.com/library/module_viewer.php?mid=48 , is a good overview of temperature with a good image of the temperature scales and conversions between different scales. Notice that the Kelvin scale starts at zero and goes up from there. This is like our car speedometer, in that at 0 Kelvin (K), molecular and atomic motions stop. As the temperature rises, atoms and molecules begin to move faster and faster.



The second thing to consider is the intermolecular forces (attractions) that exist between molecules. In the D2L content slides there are a few types of attractions described, notice all of these are defined by the attraction that exists between positive and negative charges. Water is a great example of a molecule that has strong attractions that we call hydrogen bonding. It is this strong attraction that makes water a unique molecule on our planet. It turns out that the hydrogen atoms tend to be positive in charge, and the oxygen atoms tends to be negative in charge.



Tasks to be completed for Acitivity 6

1. Convert 0°F, 32°F, 70°F, and 212°F to Kelvin

a.      0°F= 273.15

b.     32°F= 305.15

c.      70°F= 343.15

d.     212°F= 485.15

2. Complete the Teaching Idea: States of Matter Simulation Lab by Kelly Vaughan. Complete the lab worksheet as if you were a student, and then post this on your blog. You can scan it or just take a picture of it. 

States of Matter Simulation Lab.

Before you open the simulation:

PREDICT

1. Draw a diagram below showing what you think the molecules will look like for each state of matter, solid, liquid, and gas. Write a sentence below each diagram predicting what the motion of the molecules will be like.

2. If you start with a substance as a solid, what will happen to the molecules as you add thermal energy (heat)?                Be adding heat to a solid the molecules will start to separate and turn into a liquid. If you have enough heat for a long time, it will continue to turn into a gas.

ONCE YOU HAVE COMPLETED THIS PAGE, YOU MAY BEGIN THE SIMULATION.
Open the simulation. You will find it in a folder on your desktop labeled “States of Matter Simulation.”

INVESTIGATE:

3. Use the menu on the right side of the program to select Water and Solid. Draw and describe what you see in the space below.

4. Now, use the slider on the bottom of the program to Add Heat. Notice the thermometer at the top of the program. What temperature scale is this thermometer showing? The temperature is showing kelvin.

5. What happens to the water as you increase the temperature? When I add heat to the liquid, the molecules start to come apart and more freely around the whole can. Not staying together. When adding heat to solids, they perform the same way as the liquids do.

6. What is the melting/freezing point of water in Kelvin? The melting point of water in Kelvin is = 273.15K the freezing point is = 273.15K. They are the same

7. Add heat until the temperature is just below and then just above the melting point of water. How is water different below its melting point and above it?

8. Draw and describe what water looks like as a liquid.

9. What is the boiling/condensation point of water in Kelvin? The boiling condensation point of water is Kelvin is 373.15K

10. Continue to add heat until you are just below and then just above the boiling point of water. How is water different below its boiling point and above it? Water is different  when the temp is just below the boiling point at 370 K by the water molecules still jumping around on the bottom of the can, but more are becoming lose from the group and moving quite faster . Water is different when the temp is just above this point at 379K by all the molecules being off the bottom of the can, and more and more are reaching the top of can. The molecules are move faster and jumping much higher.

11. Draw and describe what water looks like as a gas.

12. Choose one of the other three substances listed in the menu on the right. Investigate what happens when you add and remove heat from this substance. Use the buttons on the right to see this substance as a solid, liquid, and gas. Draw and describe its properties in the table below.

                                                        

Substance Selected: Argon

ANALYZE:

13. How was this substance similar to water in each state of matter? How was it different?

For each of the states of matter, I noticed that there was a lot of similarities and not to make differences. All the solids were very close together at the bottom of the can. The liquids were still connected but moving a little faster, and gas was jumping all over the place not in a group setting. One difference that I noticed was that under the oxygen even in the gas state, the molecules were moving in pairs. Two molecules were glued together jumping and spinning around. 

14. Were your predictions (see p. 1) correct or incorrect? Explain.

My prediction were very close to what the molecules showed me. I believe this is because I have avery good understanding of what a gas, liquid and solid look like and I know that the molecules had to look something like that.

BONUS: Optional, worth up to 10 points added to the lab’s final grade

15. Choose a substance other than water from the menu on the right side of the program. Use the slider to add and remove heat. Based on what the molecules do, figure out the approximate temperatures of the melting point and boiling point of this substance. (Hint: The temperatures given when you click solid, liquid, and gas are NOT the melting and boiling points.)

Substance: Neon

Melting Point: 24K

How did you figure it out?

The way that I figured this our was I slowly started to heat up the temperature until the molecules started to spread apart and go from sitting on the bottom of the can to moving up to the top.

Boiling Point:      26K

How did you figure it out? The way that I figured the boiling point was to continue to raise up the heat until the molecules were no longer in a group at all and they were all on their own. Also known as a gas once it gets this hot.

3. In the States of Matter simulation, choose the Solid, Liquid, and Gas Tab at the top of the screen. Choose the water molecule and cool the water to 0 K. Describe how the water molecules are aligned and attracted to each other. Which atoms are attracted to which other atoms?

hot 25K movement, moleules have space inbetween them, fly around all over area, most fast, no order

cold 0k slow down, bunch together, no space between them, sink to bottom of area

Which atoms are attracted to which other atoms?

cold attracted to cold

hot repelled from hot

4. Switch to the Phase Changes Tab on the States of Matter simulation. Notice how on the bottom right there is a small red dot that indicates where the system is at as far as temperature, pressure and state of matter. Play with the simulation to notice changes, notice that when you push down the pressure can go way up and explode the box. On your blog, report a temperature and pressure required to make oxygen a liquid. This is sometimes how the oxygen exists in pressurized oxygen tanks, perhaps like ones you may use to go diving.

Triple point: Temperature 55K = Pressure= 0   ATM
                                          55K                     .05 ATM

The more pressure, the less amount of heat needed to liquify oxygen at a fast rate.
The less pressure, the more amount of heat is needed to liquify the oxygen faster.
temp 49K+
Adding more oxygen does not make the process go faster or slower.

5. List and describe at least two Science Standards that this activity addresses.

Standard D 4.3 “Understand that substances can exist in different states-solid, liquid, gas”

            This science standard is addressed throughout the whole activity. This activity deals with solid, liquid, and gases as being different elements in the beginning. Later on in the activity we learn how a liquid can turn into a gas. How a gas solid can turn into a liquid and so on.

Standard C 4.5 “Use data they have collected to develop explanations and answer questions generated by investigations”

            This activity addresses this standard because of how easy it was for me to answer the questions once I had completed the activity. While I was in the process of doing the tests with the simulations, I was keeping track of my numbers and collect important data. At the end of the test when it came time to answer the questions all I had to do was look at my written results and not have to do the test over again. Saves time and much easier to put into my own words.