Blog Post #6

The main ideas in SG Chem1 this week were pressure and particle movement. Pressure is the force applied to an object. We measure pressure in atmospheres (atm). Particle movement and pressure relate because they both relate to energy and temperature. Particle motion always involves energy and pressure is energy per unit of volume. We also did experiments on these subjects, too. We measure temperature in degrees Celsius or Kelvins.

We did an experiment early in the week where we put Luke on an inflatable raft and four students blew air into the raft to inflate it. Then we whiteboarded the experiment. It explained a lot about particle movement. Air particles are moving randomly in the air at all times. Then when the students blew air into the raft, the amount of force exerted outward from the raft, or the pressure of the molecules pushing inside of the raft is larger than the force of gravity pushing Luke down. Here is a video of the students blowing Luke up:

The rest of the week, we did three important experiments involving pressure. We compared pressure to temperature, number of particles, and volume. 

For the pressure to temperature experiment, we attached temperature and pressure sensors to a computer and used LoggerPro to record our information and measure the pressure and temperature. We put a temperature probe in a beaker and added hot water to cover most of the flask we put in the beaker. We then recorded the temperature. Then we repeated the process with cooler water, ice water, and alcohol with ice in it. We predicted that, as Pressure as the y-axis and Temperature as the x-axis, the line on the graph would go up and to the right, and we were correct.

On the second experiment, pressure versus number of particles, we attached a pressure sensor to our computer and hooked up LoggerPro. We measure the number of particles in puffs, and again predicted that, as Pressure as the y-axis and Number of Particles as the y-axis, the line on the graph would go up and to the right. It did.

For the third and final experiment, we again attached the pressure sensor to our computer. We then attached that to our syringe. We started at 14 mL, recorded the pressure for that, then slowly pushed down to 12, then 10, 8, and 6. We predicted that with Pressure as the y-axis and Volume as the x-axis, the line on the graph would be straight and go down and to the right. We were close, except the line was curved. 

From these experiments, we concluded that pressure is inversely proportional to volume, directly proportional to number of particles, and directly proportional to temperature. 

One question I have from this week is: how is force different from pressure? I know pressure is a force, but then why not just call it force? Is all pressure force, but not all force pressure?

I participated thoroughly during the experiments this week and feel I have learned a lot about particle movement, energy, and pressure.