Thursday+(Gas+law+basics)


 * BELLWORK (Including character education, ACT math and vocabulary)**

l “The surest way to corrupt a youth is to instruct him to hold in higher esteem those who think alike than those who think differently.” Friedrich Nietzsche
 * Quote**

Ecstatic //–adjective//
 * Vocabulary**
 * of, pertaining to, or characterized by ecstasy.
 * 1) subject to or in a state of ecstasy; rapturous.


 * CLASS ACTIVITES**
 * Introduction to the gas laws**
 * The bellwork asked a series of question meant to test the student’s familiarity with the gas laws.**

1) What will happen to the pressure in your tires if the temperature drops 40 degrees over the night?

a) Pressure will increase b) Pressure will decrease c) Pressure will not change d) Cannot determine

2) Would happens to the temperature of a gas when the pressure is increased and the volume is also increased?

a) Temperature will increase b) Temperature will decrease c) Temperature will not change d) Cannot determine

3) Would happens to the temperature of a gas when the pressure is increased and the volume is decreased?

a) Temperature will increase b) Temperature will decrease c) Temperature will not change d) Cannot determine

The students did well on the first question, but not so well on the last two. In fact, the students had no clue on the last two questions, they might as well have been guessing.

I asked the students to explain what pressure was using the tire question as a guide. I asked each students to draw a before and after picture of the tire to help explain what pressure was. As each group did this, I moved around the room and asked the students questions about what they were drawing. This was very interesting. At the end of this activity I asked the students who’s answers were the most accurate to explain their definition and pictures to the class. This only got the ball rolling.
 * Modeling the tire question**

I asked the students, “What caused the tire to be expanded?” They responded that the air caused the tire to expand. I asked, “Why will it be under less pressure when the temperature was lower?” They responded that the air got closer together when it got cold. After a series of questions I got the students to believe that warmer air moved more rapidly. Once I had this, we were ready to model the gas laws.
 * The gas laws make logical sense, but not all students are quick to see this.**
 * Boyle, Charles, and Gay-Lussac’s laws**

We cleared the desks out of the center of the room and formed them into a piston. Each student was a “particle” of gas. The students were set in motion within the confines of the piston and instructed to count the number of times that they contacted the walls of the piston. After a series of questions I got the students to realize that the total number of times the wall was contacted was analogous to the pressure, but eventually the got on board.

The students were set in motion at three different “volumes” (I reduced the area in which they were free to move) to derive the inversely proportional relationship between pressure and volume. At the end of each round each student told me the number of time he/she contacted the desks that bound them, and I used excel to determine the sum. I then used excel to graph the results.

This process was repeated three more times at constant volume with “temperature” be varied. The students decided that “temperature” could be changed by changing the rate at which people walked inside the area. Again, they counted the number of times they struck the desks and reported it to me at the end of each round. Totals were summed and the data was graphed using Excel. We concluded that pressure and temperature are directly proportional.

Once we determined that temperature and pressure are directly proportionally, and that pressure and volume are inversely proportional, we were able to derive the combined gas law. Armed with the combined gas law we will reinvestigate the questions what were asked on the pretest:
 * The combined gas law**

a) If pressure increases and temperature remains constant, volume will b) If temperature increases and volume remains constant, pressure will c) If pressure decreases and volume remains constant, temperature will d) If volume increases and pressure remains constant, temperature will e) If volume decreases and temperature remains constant, pressure will

I showed each student how to solve these problems using the combined gas law. This procedure is very similar to some of the work that we did with the density equation. The students learned this skill quickly and were proficient at solving these problems by the time class ended.

I suspect that nearly every student will perform well on the first bellwork question (what happens to tire pressure when it gets cold). The following two questions will almost certainly show random guessing on the part of the students. I think that this lesson will be very effective, I have used it before and it has worked.
 * __What I expect__**


 * Reflection**
 * I think the activity went well, but I’m not sure how many of the students really “got” the activity. I know that several of them did get it and therefore truly understand what’s going on at the molecular level. Sadly, I fear that may of them had no clue why they were walking around the class for half an hour. I look forward to re-administering the pretest after break to see if any of them really “got” it.**