Chemistry Blog #5

The main idea that we have been focusing on this week in chemistry was energy. The first thing we focused on was creating energy bar graphs. The energy bar graphs has 3 bars in it, the E(th) which is the temperature and the E(ph) which is the phase and the E(ch) which is the chemical aspect. Theres 2 graphs, initial and final, and also the energy flow which shows if the energy is flowing in or out of the object that is changing. For this energy bar graph, the water starts as liquid and it starts as room temperature. Then, it freezes, goes down to -8 degrees celsius and becomes a solid. Because when something becomes a solid and gets colder, it looses energy due to the fact that the particles are slowing down and that theres less space for the particles to move around in so they can't move as freely.

For this energy bar graph, the soda starts cold and as a liquid, and stays a liquid but becomes room temperature. The energy flow is directed inwards. This is because as the soda warms up, the particles speed up and create a higher energy, so energy is added when the soda becomes room temperature. For a energy bar where something is turning into a gas, the energy flow would also be going in because when something becomes a gas, the particles speed up so much they break away from each other. For something to become a gas it has to become really hot so the particles speed up a lot and that creates a higher energy. The second thing we were focusing on is quantitive energy problems. One of the first things we learned is that energy is a substance like quantity that is always involved whenever a system undergoes change, such as hotter to colder, faster to slower, or higher to lower. Energy is stored and transferred in different ways but it never comes in different forms. Heat is a way to transfer energy but an object doesn't store heat. Heating a system increases its thermal energy by a process of energy transfer through particle collisions. Temperature is a way to assign a numerical value to thermal energy, but temperature and energy aren't the same. As temperature increases, particles move faster and faster, so at some temperature, the particles are moving so rapidly that they can no longer maintain the arrangement of a solid, so they break free into the shape of a liquid. Then, as the temperature keeps increasing, the same things happen and particles break free into a gas phase. The flat region of a heating curve is where the phase change is happening. When you look closer at the phase change region, you can see that it is rigid, moving up and down at very small amounts. This is because when energy enters the thermal account, it raises the temperature and then the energy is immediately transferred to the phase account , which lowers the temperature. Now for the quantitive energy problems.  These let us know how much energy is transferred during these changes. We can do this by the equation Q= mc(change in temperature). Q is the amount of energy transferred, m is the mass, c is the specific heat. and change in temperature is the difference between the initial and final temperatures. That is the equation to figure out how much energy is transferred when the substance is heating or cooling. There are other equations for when a substance is freezing or melting, which is Q= (change in mass)H(f) , where H is the energy constant and (f) is for fusion. For when a substance is vaporizing or condensing, the equation is Q=(change in mass)H(v), where H is the energy constant and (v) is the for vaporizing.

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

Chemistry Blog #3

The main ideas that we have been focusing on are energy and pressure. We learned that there are 2 types of energy, kinetic and potential energy.Potential energy is energy that is stored and not yet used, Kinetic energy is energy that is moving. Energy creates heat and heat is an example of kinetic energy. We did an experiment showing how food coloring moves in different water temperatures, The food coloring in the hot water moved faster and spread throughout the water faster. This is because the hot water is conducting more energy and the particles are moving faster. The food coloring in the cold water spread much slower, because there's not as much energy because the particles are moving slower. We talked about why the alcohol level in a thermometer rises or falls when the thermometer is in contact with warmer or colder objects, The answer to that is thermal expansion, if the temperature of whats being measured is hotter than the alcohol then the alcohol will rise in the thermometer. Same for when the temperature is colder than the alcohol, the alcohol will fall. Also, you can't measure your own temperature with your own hand because it'll feel the same temperature as your forehead because you have the same body temperature all over. Next, we started talking about pressure,  We can drink a liquid through a straw because of pressure. When you suck the air out of the straw, you're creating a vacuum. The liquid fills the straw because of the vacuum and because particles move from high to low pressure. So the liquid moves from the cup, or can to the straw. We read an article about scuba diving,gas and pressure related to it.The water pressure, as the divers descends, increases greatly. The gas and pressure in your body increases and the gas has to go somewhere. The gas either gets exhaled, or goes into the bloodstream. Diving can be very dangerous, you have to descend and ascend slowly so your the gas and pressure in your body can change with the water pressure. If it can't change with the surrounding air pressure, the alveoli in the lungs can rupture and air can enter the bloodstream which causes a blockage which can lead to many problems and may result in death. There were a few laws mentioned in this article. Boyle's law states: The volume of a gas sample varies inversely with its pressure. Harry's law states: The amount of gas that will dissolve in a liquid at a  given temperature varies directly with the pressure above the liquid. Next, we did a lab that was called the Pressure vs. Volume lab. We connected a syringe to a pressure sensor and connected that to LabQuest, First,we recorded the pressure when the syringe was at 10mL. That was .98 atm. Then we recorded the pressure every time we went down 2mL. At 8mL, the pressure was 1.107 atm. The pressure at 6mL was 1.54 atm, 4ml was 2.1 atm and the pressure at 2mL was 2.3 atm. The we went back up, starting at 10mL, we went up every 2 mL. At 12mL ,the pressure was .84 atm. At 14mL, the pressure was .71atm. The pressure at 16mL was 0.62 atm, 18mL was 0.56 atm and at 20mL , the pressure was 0.51 atm. From this lab, we learned that the smaller the volume, the higher the pressure, and the bigger the volume, the lower the pressure.

Chemistry Blog #2

The main idea that we have been working on in chemistry this week is density. We have learned that density is the amount of particles packed into a space. The density of an item, or element, does not change no matter the size of the item or element. The formula for density is density=mass/volume. First we explored graphing mass,volume and density. If  mass, in grams, is on the x-axis and volume, in cm3, on the y-axis, the density is slope of the line. So for example, if the mass of something is 14, and the volume is 7, then the density is 2. And to graph it, the slope would be 2.

 The next thing that we did while looking at density was the Density of a Gas lab. In this lab, we filled a trough with water, put a jar filled with water over the hole in the bottom of the trough. Then we filled a flask with water, wrapped an alka-seltzer tablet in aluminum foil and put that in the flask, then we attached the trough and flask. What happened, is the water in the jar, which was in the trough, decreased. To be honest, I don't know why this happened because I really don't understand this lab. I know this happened because of the gas from the water and the alka-seltzer tablet. Our data was 127.2g was the mass of everything before we did the lab, and 126.7g was the masss of everything after the lab.

After the Density of a Gas lab, we did a Thickness of Aluminum Foil lab. What  we did in this lab, is  we had 2 pieces of aluminum foil, one regular and one heavy duty. We were also given the density of aluminum. We found out the masses of both foils, put it in the equation, density=mass/volume, and figured out the volume. To figure out the thickness, we can insert the volume into the equation volume=length x width x height. The thickness in this case is height. So then we measured the length and width and put all of that into the equation to figure out the height.

Chemistry blog #1

The main ideas that we have been focusing on, in Chemistry, so far are, matter,mass, volume, density, significant figures, zeroes and measuring all of those things. We have looked at the relationship between matter and mass, mass and volume, density and mass, and density and volume. In exploring matter and mass, we learned that matter is what everything is made out of, it takes up space, its composed of atoms and elements, and it has 3 forms, solid,liquid, and gas. Then we learned that mass is the amount of something, or how much space something takes up. That is the difference between matter and mass. To explore mass a little bit more, we did a lab called the Mass and Change lab. In that lab we massed different items, then changed them either chemically or physically and massed them again. This helped us understand how and why mass may or may not change, for different reasons.Then we compared mass and weight, and came to a conclusion that weight and mass are very different, weight is how much something weighs and mass is how much space something takes up, and mass doesn't change no matter where you are. For example, being on the moon would change your weight but not your mass because there is still the same amount of matter. Next, we looked at the relationship between volume and mass. Volume is more of how much space something has, or can be filled up with, almost. For example, a jar has a certain amount of matter, which is its mass, but how much it can be filled up, is its volume, That can be tested by the water displacement test.We did another lab on volume. In the lab, we had 5 objects and we measured the volume of them in 2 different ways, using measurements and formulas, and then using water. This lab just gave us 2 different ways to measured volume and which way is more accurate. After that, we moved onto density. Density is how dense, or compact something is.  Density, mass and volume are all different but they do relate to eachother quite a bit. The equation for density is Density= Mass/Volume, so in order to find the density of something, you need the mass and volume. Or, if you have the volume and density, you can find the mass by rearranging the equation to look like this; Mass=Density x Volume. Then we started talking about measuring correctly, significant figures are zeroes. To measure correctly, you can't measure too many decimal places beyond where the gradations on the measuring tools go. So lets say on a graduated cylinder the gradations are at every ones place, you are only allowed to measure to the tenths place and no beyond that. The number in that tenths place is the uncertainty of the measurement. For significant figures and zeros, we learned a number of rules about them. 

1. Non zeros are always significant
2. Sandwich Zeroes/ Captive Zeroes are always significant (103)
3. Leading Zeros are not significant
4. Decimal Trailing Zeroes are significant
 5. Whole number trailing are not significant