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Steven Dziuk SC300 Big Ideas in Science: From Methods to Mutation Unit Five Project Temperature and Equilibrium Virtual Lab June 15, 2010 Temperature and Equilibrium Virtual Lab This virtual lab studies the affects different temperatures have on two sets of molecules, both separate and when mixed. I will compare how these two sets of molecules react in colder temperatures; then hotter temperatures; and how the two react with each other. Then, based on these findings, I will offer theories of two case studies involving 1) honey added to two cups of tea and 2) a package of smelly limburger cheese opened on a winter and summer day.

The experiment begins with a chamber that is divided—on the left are 20 red molecules, on the right, 20 blue. Each molecule is given a maximum mass of 199 amu. When I lowered the temperature on the red side to 1K, these molecules slowed way down. The blue molecules, at 273K, moved quickly, with much more energy. Lowering the temperature seems to “thicken” the area the molecules move in. These molecules slow down to almost a stand-still. If the temperature was lowered further, the molecules would eventually stop or “freeze”.

The molecules would not be moving and bumping into one another, which would result in a loss of heat or energy transfer (Trefil & Hazen, 2011, p. 75). The next step was to lower the temperature on the blue side to 1K also. I added more molecules to each half, bringing the total up to 99. The additional molecules seemed to slow down their movement even more. At 20, the molecules had a chance to “explore the chamber”. When the number increased to 99, there was less room for the molecules to move. Some even appeared stopped, or frozen.

The higher volume of molecules at the lower temperatures appeared to make the chamber denser. Removal of the divider allowed for the mixing of the 99 blue and 99 red molecules at temperatures of 1K and 999K: “Mixing at 1K” 5 minutes elapsed: Some mixing had occurred. Mostly, the molecules stayed to their original sides. 10 minutes elapsed: The mixing did not change much from the five-minute mark. There was an average of five to ten molecules that did transfer to the opposite side. It seemed that the cold temperatures, chamber density and number of molecules kept the mixing to a minimum. Mixing at 999K” 27 seconds elapsed: Both colors moved very fast. The result was blue molecules reaching the opposite red chamber wall and the red reaching the opposite blue chamber wall. 1 minute elapsed: A complete mixing of all molecules resulted. This virtual lab shows how temperature changes the reaction of molecules in a substance. As temperatures decrease, the molecules slow and do not collide as much. With little or no collisions, there is less probability for heat transfer and equilibrium.

The higher the temperature, the rate of heat transfer is greater, until equilibrium is achieved (Trefil & Hazen, 2011, p. 75). The molecules at these higher temperatures collide and share energy until each molecule shares the same amount. Let’s put these findings into practice. The first example involves two cups of the same tea. One is at a temperature of 200F, while the other measures in at 45F. When a spoonful of honey is added, what are the results? 200F: This water is extremely hot, but not quite at the boiling point (212F).

When the honey is added, the water molecules are moving extremely fast and with a lot of energy. The honey will be bombarded by these water molecules and begin to break up as heat is transferred. The honey will go from being thick, to thin, almost appearing to melt in the hotter water. The honey reaches equilibrium with the water when the mixture occurs—the honey molecules receive the heat transferred from the water molecules, resulting in faster, thinner honey molecules. 45F: In this case, I will assume that the honey is at equilibrium with its urroundings, room temperature (72F). If this is true, when the honey is added to the colder tea, it may sit on top for a bit. As the heat from the honey transfers to the colder water, the water molecules will speed up. This allows the tea to become thinner and the honey will begin to sink in and dissolve. The first statement of the second law of thermodynamics describes the behavior of two objects at different temperatures (Trefil & Hazen, 2011, p. 82). Here, the faster molecules of the honey are moving the slower molecules of the tea along.

The second example involves me enjoying a snack of stinky limburger cheese in an open parking lot. There is a group of shoppers 50 feet away. How long will I be able to enjoy my snack before the group complains on a summer day compared to a winter day? Summer: I will assume that wind plays no role in this experiment. The warmer atmosphere contains fast-moving molecules. When I open the container, the fast molecules will collide with the cooler limburger molecules. Those limburger molecules will be pushed out into the air and travel faster and farther throughout the parking lot.

The group 50 feet away will react quickly as they catch a whiff of what I am ingesting. Winter: Here, the opposite of the summer is true. The air is thicker than the aroma of the limburger. The warmer limburger molecules want to transfer to the colder air, but are slowed by the tightly-packed air molecules. Equilibrium may be achieved, but it will take longer. The group 50 feet away may not even notice what I am eating, or it will take a while before they do. Heat is energy that always moves from a warmer object to a cooler one.

Temperature is a measure of how molecules move in a substance (Trefil & Hazen, 2011, p. 75). The warmer the temperatures, the more molecular motion, the more heat (energy) is given off. Start to cool the temperature and the molecules slow down and there is less energy given off. This experiment was an examination of how substances are changed by adding or taking away heat. How molecules react in a cup of tea, a container of limburger, or even in a weather pattern, affect how we live our everyday lives. Reference: Trefil, J & Hazen, R. (2011). The sciences: An integrated approach. Hoboken, NJ: John Wiley & Sons.

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