Lab 5.1 Alka Seltzer Poppers

In this lab, I started by doing a controlled experiment. The control consisted of a 1/4 tablet of Alka Seltzer being dropped in 10 mLs of room temperature vinegar. For each test after that, I changed one variable. For the temperature test, instead of room temperature vinegar, I used vinegar that had been heated, and vinegar that had been cooled over ice. For the surface area test, I did one test with a 1/4 tablet of alka seltzer that had been crushed, and another test in which a 1/4 tablet of alka seltzer that had been ground into dust. For the vinegar concentration tests, I did one test in which I used 5 mL of water, and 5 mL of vinegar. For the second test of concentration,  I used 2.5 mL of vinegar, and 7.5 mL of water. It is important that I first created a controlled experiment, so that I could compare the results of the experiments to how Alka Seltzer normally reacts. The procedure was effective in determining how each variable influenced the rate, because I only changed one variable at a time, whilst keeping the other conditions the same. If I had changed more than one variable at a time, I would not be able to obtain accurate results.
By changing the temperature of the vinegar, the particles will move faster or slower, depending whether or not the temperature of the vinegar is increasing or decreasing, and the particles may collide more often, so they will react quicker. By decreasing the amount of vinegar, the Alka Seltzer will react slower because t is apparent that the Alka seltzer reacts better in vinegar than it does in water. If the tablet is crushed, there is more surface area, so more of the particles will be colliding more often, so the reaction will speed up.
Enrichment: An example of a biological catalyst is Amylase. Amylase is found in saliva, and it helps any ingested starches break down into simple sugars. It works like a key, because it helps the saliva molecules fit to starch molecules, in order to chemically break them apart.

Lab 4.2 Heating and cooling curves

The melting point of Lauric acid is about 45° Celsius. The freezing point is about 45° Celsius. They are the same because they involve phase changes between the same two phases (liquid and solid). The only difference is that heat is being added to reach the melting point, and heat is being removed to reach the freezing point. So they are the same, only in different directions. I determined the freezing and melting points, because on the graphs, the line plateaued at about 45° Celsius. This means that during that time period (roughly one and a half minutes) the Lauric acid was changing states of matter.

On the heating curve, when the substance is in either state of matter, (liquid of solid) the kinetic energy, or temperature of the Lauric acid is increasing. This is because the substance is heating up and the molecules that it is composed are beginning to move faster. The potential energy is at a constant because the substance is not changing phases of matter during this time. This is similar for the cooling curve, only instead of increasing, the kinetic energy (temperature) is decreasing, because as heat is being taken away, the molecules are slowing down. The amount of potential energy is increasing when the Lauric acid is melting, and decreasing when it is freezing. There is more potential energy in a liquid than in a solid, so as it is changing phases of matter, the potential energy is also changing.

Enrichment: The actual melting/ freezing point of Lauric acid is 43.2° Celsius. My results were slightly off because I was only calculating the temperature every fifteen seconds. If i were to record it every second, then the data may have been more accurate. My percent error was 4.17%.

Lauric acid is used to help scientists learn the molar mass of unknown substances. They mix the unknown substance with the Lauric acid and calculate the temperature at which the mixture freezes. The chemical formula is C12.

Source: http://en.wikipedia.org/wiki/Lauric_acid

Lab 4.1 Having Fun With Air Pressure

1. A becrease in pressure causes the volume of a balloon to increase.
2. Adding more pressure increases the pressure in that bottle.
3. As the volume of a cylinder in increased, the pressure will decrease.
4. Inreasing the pressure in a tire by adding more gas will cause the volume to increase.
5. As the temperature of a closed container of water in increased, the amount of water vapor above the water causes an increase in vapor pressure.
6. As the air pressure of a liquid is increased by adding more air, the boiling point of the liquid will decrease.
7. If a balloon filled with air is taken under water to a depth of ten feet, its volume will decrease.
8. The temperature of a beaker of boiling water will increase as more heat is added.
9. Hot air rises because it is less dense than the cold air around it.
10. When heated, the volume occupied by air in the balloon will increase.
11. The lowest possible achievable temperature in -273 degrees celcius, which is also expressed as 0 degrees kelvin.
12. .88 atm.
13. 130 degrees kelvin is 403 degrees celcius.

Enrichment: The collapse of the tanker car shown in the picture can be explained quite simply. When the men cleaned its interior with hot water, they made the mistake of sealing it. Inside the tanker car, the air particles were mowing very quickly due to the high temperature. As the temperature on the outside of the tanker cooled, so did the temperature on the inside of the tanker. This caused the particle motion isnide the tanker to decrease, lowering the pressure. As the air may have warmer up some throughout the night, the pressure on the outside of the tanker car was greater than the pressure on the inside of it, thus causing it to collapse upon itself.