Accel. Chem. Blog Two

The first demo we did for this section was the one with the stink spray, which actually smelled quite nice. It showed diffusion through the air, as the particles of the spray, which started out at the front of the room, were spread around by the other air particles until they had evenly spread throughout the room. Similarly, we next did the demo with the hot and cold water. For this, drops of food coloring were put into hot and cold water and left to mix around. The food coloring in the hot water mixed much more evenly, and had distributed throughout the whole container after a few minutes. In the cold water, the food coloring mixed a little, but not much. The disparity in results was caused by the fact that the hot water has more energy in its particles, meaning they will bounce around more and move the food coloring particles around faster than in the cold water, because the cold water has less energy.

Later, we did a computer simulation that demonstrated how gas particles move. It showed that gas particles transfer energy when they bounce off each other. The transfer of energy is demonstrated by one particle gaining speed and the other losing speed. It also showed that particles of different sizes will move at different speeds, because it takes the larger particles longer to heat up and get that energy from heat. After this, we did a solid, liquid, and gas demo where we learned about the different qualities of the three states of matter and recorded them in our notebooks. For example, we were taught that solids have their particles in a lattice and are vibrating, liquid particles are free to move past and along each other, and air particles move randomly in all directions. The second part of this was the Eureka videos, which acted as a sort of review. They gave us the phrase "dance of the little lumps" to describe molecular motion, which is hilarious.

The last two experiments we did involved blowing people up and straws. For the first one, we demonstrated the power of air pressure by inflating a garbage bag while someone was sitting on it.

 Before

After

The bag was able to support Kate's weight because of air pressure. When all of us were blowing in though our straws, the amount of air in the bag increased, and eventually all of the particles bouncing off the walls of the bag was enough force to actually lift Kate off the ground. The straw experiment started by all of us getting Koolaid pouches to drink and then having to explain why the liquid rises up the straw. It's not because of suction, as I previously thought, but instead because you create a vacuum. When drinking from a straw, you suck out all the air, creating a pressure difference in the straw and in your  mouth, which in turn causes the liquid to rise up the straw and get to your mouth.

Reflection Blog #1

The first week and a half of chemistry have been great! I like the labs we've done, especially the one that involved working with chemical and physical changes. Unfortunately, I wasn't able to experience the second half of the lab, but the part I did get to do helped me learn a lot. I also like how the notes haven't been too crazy. There have been some, but not loads. I've learned quite a bit through the labs we're doing, and that coupled with the notes about them has helped me to learn and remember the information I need to know.

The first lab that we did involved boats and making them float. While the title always trips me up when trying to say it, it was a great reprieve from the endless amounts of syllabi and forms to be signed on the first day. Not only that, but it was a fun lab to do. It was a challenge to figure out how to make the best boat out of the cheapest items, and though my group lost, we learned a lot from the winning group as to how it was best done.

Next, we did the lab on weight and changes in mass. Things such as burning steel wool, melting ice in water, and more helped us discover that when combining two things, such as the melting ice and water, there should be no change in weight because it's only a physical change. However, when burning steel wool, it got heavier because the change is a chemical one. As it was burned, the metal oxidized, meaning that it now has the mass of both the steel wool and the oxygen atoms. The primary objective of the lab was to teach us the difference between physical and chemical changes, and it worked. I learned that an object does not gain mass if the change is only a physical one, because the change only affects the appearance of an object. However, if the change is chemical, the object can gain or lose mass because it is being changed on a molecular level. The object is the same after a physical change, but different after a chemical one.

 Kate, pictured here mixing sugar and water as part of this lab and less than enthusiastic about me photographing her. The change was a physical one.

Kate pouring the sugar.

After this lab, we did one that focused more heavily on physical and chemical changes. We held wire in  fire, burned magnesium, and mixed acids. Unfortunately, doctors appointments meant I wasn't able to be there for the acids part, but I think I was able to still get a benefit from this lab. I won't go too far into the whole physical and chemical change part, because I already did that above, but I do want to say that the wire experiment was a physical change and the magnesium was a chemical change. Since only the physical appearance of the wire was changed, it was a physical change, and since the magnesium turned to ask after being burned, it was a chemical change.