Chemistry Blog #4

The main idea we looked at this past week was pressure and the relationship between pressure, volume, temperature and the number of particles. We finished part 2 and part 3 of the PTVn lab, which was testing number of particles and temperature.The purpose of this lab was to test pressure with different variables to see how those variables affect pressure and to see the relationship between pressure and volume, pressure and temperature, and pressure and number of particles. We were trying to show that pressure increases then the volume decreases, that pressure increases as the temperature increases and that pressure increases as the number of particles increases.  In my previous blog, I gave the results for the pressure vs. volume lab which was that, as the volume increases, the pressure decreases. For the second part of the lab, we tested the relationship between pressure and number of particles. The lab didn't really go as planned but what should've happened is that the pressure should've increased as the number of particles increased. That should've happened because as more particles are added, it becomes more crowded in that space so there are more collisions. These are the results for that lab:

puffs	5.00	7.00	9.00	11.0	13.0	15.0	17.0	19.0
atm	.988	.986	.985	.990	.987	.987	.986	.986

For the third lab, we explored the relationship between pressure and temperature. This lab didn't really go as expected either, but what was supposed to happen is that the pressure was supposed to increase as the temperature increases.This is because as the temperature increases, the particles move faster and when they move faster, there are more collisions with the side of the container and each other. These are the results for that lab:

Temp	42.6	41.9	40.0	36.7	32.8	27.1
atm	.983	.983	.98	.983	.983	.983

Next, we were looking at PTVn problems and how to solve those. A PTVn problem is word problem where any of the 4, pressure, temperature,volume or number of particles are changing and you're given the initial and final measurement for some but you have to figure out the final and effect for all of ones that aren't given. I think the tricky part of these problems are finding out the effect, like what happens to the pressure if the volume is increasing but the temperature is increasing? For that problem, you'd make note that the pressure would decrease for the volume but increase for the temperature. Then, the way you'd set it up would be that the higher volume given would go on the bottom of the equation and the higher temperature given would go on top of the equation. Sort of like this:

	Pressure	Temperature up	Volume
Initial	50 atm	298 K	150 mL
Final	?	323 K	163 mL
Effect	T up    V down		up

50 x 323 x 150 =49.68

298 163