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