Unit 2

In Unit 2 in Accelerated Chemistry, the class learned about the relationships between volume, pressure, temperature, and number of particles.

First we did the lab on Pressure and Volume. In this lab we observed the relationship between pressure and volume and how to make particle diagrams based on what we observed. The class white boarded particle diagrams on pressure and volume and learned how to show a higher pressure using particle collisions. The more collisions represented by the diagram, the higher the pressure is and less collisions on the diagram show less pressure. We observe more collisions because as volume gets smaller, the pressure goes up and the particles are more likely to collide with other particles and the walls of our container. Also when the volume gets bigger the particles have more room to move and collide less often with each other and the walls of the container.

The next lab we did, Pressure and Number of Particles, we observed the relationship between pressure and the number of particles in a given volume and how to make diagrams and white board those diagrams to accurately represent what we observed. We observed that when the volume and temperature stayed the same, but the number of particles or pressure went up, the pressure or number of particles also went up and when either of them went down, the other went down as well. So, as we observed the relationship between pressure and number of particles, we observed that when the number of particles go up, there are more particle collisions being observed because the volume stays the same but there are more particles to collide with each other and the container so we measure a greater pressure.

In the third lab we did, Pressure and Temperature we observed the relationship between pressure and temperature when volume and number of particles are constant. We observed that when the temperature goes up, the pressure also goes up because the particles have more energy, move faster, and therefore are more likely to collide more often with the container or with other particles. We showed this in our particle diagrams by using more “wishees” as we call them, or lines behind particles to show direction/collision than we did in the previous labs of Pressure and Volume, and Pressure and Number of Particles. So if temperature increased in the final reading in contrast to the initial, we would draw more lines, or longer lines (as shown in the picture) behind the particles and also more collisions because the pressure has gone up as well.

The class learned how a thermometer works as well. Most thermometers now use an alcohol that is colored red. When the air temperature rises, the air particles collide more often with the glass tubing that encases the alcohol and transfer energy to it, speeding up its particles and causing them to collide more with the alcohol. The energy is then transferred to the alcohol causing its particles to speed up. Because the alcohol has nowhere to go but up, it expands upward until its particles don’t collide enough to keep moving up. The opposite happens when the air temperature goes down. The air particles collide less often with the glass, which then slows down its particles causing them to contract slightly and then transfers less energy to the alcohol causing the alcohol to contract as its particles cannot collide enough to keep it up.

Finally, the class learned about air particles and pressure using straws and how we do not “suck” substances through them, but we actually create a vacuum to bring the particles up through the straw. This causes near zero pressure pushing down on the liquid, and also almost zero air particles colliding with the liquid, forcing it through the straw and into our mouths. These are all of the things my Accelerated Chemistry class learned about regarding particle collisions in Unit 2.