Week 9 Reflection

In chemistry class this week, one of the main components we reviewed involved the relations of volume, pressure, and the temperature of a gas. The volume of a gas is directly related to the temperature of a gas, meaning that if the volume is increased by 2 units, so does the temperature and vice versa. The pressure of a gas is inversely related to its volume; this means that if the volume is multiplied by 2, the pressure is multiplied by 1/2, the inverse of two and vice versa. This was extremely helpful, especially when completing PTVn charts. PTVn are story problems based on chemistry that consist of at least two the components above (pressure, temperature, volume, and number of particles). The relations reviewed above played a huge roll in solving these problems, for they helped limit certain areas with their rulings.

Also, another idea explored this week in class was the barometer. A barometer is tool used in chemistry to measure the atmospheric pressure. Our assignment was to make a barometer outside of school with a partner for class. My partner and I made sure to utilize various materials, such as a glass jar, a ballon, a straw, tape, a rubber band, and water. Our first step was to fill the glass jar up halfway up with water. After, we were to cut the balloon in half and stretch the half without the neck over the top of the jar, before sealing it with a rubber band. The straw was then taped down on top of the balloon, in the center. Then, we drew marks on a piece of paper showing where the straw originally started, along with other tick marks to show where the straw could potentially move to as the atmospheric pressure changes throughout the day and was placed behind the jar. If the pressure increased, you could tell by physically looking at the balloon; as the pressure increases, it exerts a downward force on the ballooon, causing the top of the balloon to become concave and straw to point upwards. If the atmospheric pressure decreases, you can also see this through a physical change in the balloon; since the pressure decreases, the balloon is now slightly convex and the straw is pointing downawards. In lower pressure systems, the temperature is generally warmer and the air is usually containing more moisture, while higher pressure systems usually consist of cooler temperature and less humidity and moisture in the air. This was demonstrated after the class took their barometers outside to test and everyone's straw was pointing upwards within 15 minutes, ultimately proving this to be true. This is the same for those of us here on Earth, because after all, "We are the Spongebobs under this ocean of air."

Week 8 Reflection

During chemistry class this past week, we continued our discussion of pressure vs. the changing factors of a system. In a direct pressure vs. particles system, doubling the number of particles always doubles the pressure because the have a constant ratio. Pressure is equal to the number of particles multiplied by a pressure to particle ratio. In a directly proportinal pressure vs. temperature relationship, it was odd to see the beginning of the line of the graph not start at zero, which aroused the question, do particles still move at 0 kilopascals? Though particles are still moving at 0 degrees Celsius, is there still a temperature that all particles stop moving at? It was then revealed to us that after many tests and multiple researches done on this topic, that there was an "absolute zero". This "absolute zero" is -273.15 degrees Celsius or 0 Kelvin.

This week, we were introduced to the concept of a third temperature scale: Kelvin (whose units are the Kelvin). From here, we were able to determine that while Celsius is relative to water, Kelvin is the absolute scale. When dealing with Kelvin from now on, it was agreed upon that instead of starting our graphs at zero, we would start our graphs at absolute zero, or -273.15 degrees Celsius. We then established rules for converting tempertures after noticing certain patterns in our data: degrees Celsius ---> Kelvin = degrees Celsius + 273.15; Kelvin ---> degrees Celsius = Kelvin - 273.15; degrees Celsius ---> degrees Fahrenheit = 2(degrees Celsius) + 32.

Another discussion in class involved two full 2 L bottles of water each with a tube with on a rubber stopper on top. One tube has a sealed tip, while the other's tip was unsealed. As you squeezed the sides of both bottles, you could see the pressure building up inside the bottle as it forced water up the tubes, causing them both to sink. The only difference between the two was that sealed tip tube didn't stay sunk and bounced back up. While each tubes mass stayed the same, the volume increased inside the sealed tip tube, causing it to bounce back up after hitting the bottom of the bottle becauses it was less dense. The unsealed tip tube stayed at the bottom of the bottle because its volume had decreased, which then caused its density to increase and not allow it to float.

Week 7 Reflection

In chemistry class this past week, we did a mini experiment involving water and ethanol in test tubes. One test tube had a designated amount of water in it while the other had ma atching amount of ethanol. Both had stoppers sealing off the top of them with narrow, straw-like tubes coming out of them. Each of the test tubes were placed in a flask of water over a heating plate. The heating plate was thne turned on and each of the liquids began to rise. As time went on, it became noticeable that the ethanol was rising more rapidly than the water was. We were then able to determine that as the liquid's volume increased, it's density decreased, which also caused the ethanol to rise faster than the water, for it was less dense. Since temperature is the measure of the energy (motion/speed) of the particles, we could then relate the speed of particles to the surrounding temperature. The average velocity of these particles all depended on the temperature, for particles do not move as rapidly at colder temperatures.

Another new idea that we were introduced to this week was the idea of pressure. Pressure is an inverse relationship of force over an object's surface area. For a steady force, the surface area must decrease in order for the pressure to increase; with a steady surface area, the amount of force must increase in order for the pressure to increase. We then came to the consensus that some of the factors that might affect gas pressure would be the number of particles, the volume of the gas, and the temperature. From there, we conducted an experiment to help us understand the relationship of pressure vs. the number of particles. We were to take a syringe and attach it to a Labquest, which would calculate how many kilopascals were being exerted throughout the experiment. A happy medium was established: 10 milliliters, which was where the pressure would be measured after each number of puffs. Each puff consisted of 4 milliliters of air and after each puff, the end of the syringe would be drawn to 10 mL to measure how the pressure was affected by more and more particles being added and taken away from the system. We then came to the conclusion that after each puff, the amount of pressure at 10 mL nearly doubled.

One of the other pressure experiments we did this week consisted of measuring pressure to see how it varied at designated mark. We first had to hook a syringe up to a Labquest's pressure sensor to help us obtain an accurate reading. If the syringe was pulled, the pressure would decrease, but if the syringe was pulled in, the pressure would increase. After obtaining our data, we noticed our graph looked a little more different than usual because it had a negative curve to it. In order for us to graph a linear function, we were informed that are volume measurements were to be inversed. This would help us equate the two things because they were now both consistently proportionate. By multiplying the temperature to the inverse of the calculated volume, we were able to obtain a more familiar graph, for pressure is inveresely relateed to volume at a constant temperature.