Kelly Pocian

Over the course of the past couple weeks we have been focusing on four main ideas. The relationship between Pressure, Volume, Temperature, and Number of Particles. These four things are represented by different units.

Pressure is measured in atmospheres (atm), pounds per square inch (psi), millimeters of mercury (mmHg), and kilopascals (kPa). 

            -Standard Pressure (at O*C): 1atm=14.7 psi=760 mmHg=101.3 kPa            - The pressure of a room (Proom) is at 730 mmHg

Volume is measured in centimeters cubed (cm^3), milliliters (mL), and liters (L).\

Temperature is measured in degrees Fahrenheit (*F), degrees Celsius (*C), and Kelvin (K). The form of measurement we want to use is Kelvin, as it will give us a more accurate representation of changes coinciding with the other factors. Celsius -----> Kelvin = *C+273
           

The Number of Particles (n) measured in puffs, the actual number of particles, or multiple units of a certain amount of particles. 

Through a series of labs conducted, we identified the relationships between pressure and the remaining three factors: Pressure vs. Volume, Pressure vs. Number of Particles, and Pressure vs. Temperature.

1: Pressure vs. Volume: In this lab we used a Pressure sensor and syringe. We filled the syringe with 5.8 mL of air particles and compressed these particles/expanded the volume of the syringe given our instructions. We found that this was an inverse relationship, as when the Volume was decreased the Pressure increased, the constant is found by using the formula k= P/V

                                                                   

                                                                       Results

    Volume (mL)       Pressure (kPa)      Constant (k=PV)
       5.8                       190.54                         1100
       9.8                       104.80                         1000
      11.8                       86.91                          1030
      13.8                       76.49                          1060
      15.8                       65.07                          1030
      17.8                       58.85                          1010
      19.8                       52.78                          1050

     


2: Pressure vs. Number of Particles: In this lab we once again used the Pressure sensor and a syringe. In this case a puff is used in the measurement of the number of particles. We took the syringe and filled it to a certain mL marking, with every 2 mL the number of particles went up one "puff". We then attached the syringe to the pressure sensor and compressed this amount of particles into 10mL. Thus, we examined how the amount of particles affected the pressure if  both the temperature and volume remained constant. We found that the relationship between Pressure and Number of Particles is a direct relationship, as when the number of particles increases, in turn, so does the pressure.

                                                                    Results

Number (Puffs)              Pressure (kPa)                    Constant(k=P/n
          1                                 27.11                                      27
          2                                 44.59                                      22
          3                                 63.58                                      21
          4                                 80.80                                      20
          5                                 99.52                                      20
          6                                117.35                                     20
          7                                136.89                                     20




3: Pressure vs. Temperature: In this lab we attached the pressure sensor to a glass flask. We had four beakers ranging in temperature from ice-water to boiling. We placed the flask in all four, measuring the temperature of the water and the pressure exerted by the air particles inside the flask when heated. Through this experiment we were able to analyze the effect of temperature on pressure. We found the relationship between Pressure and Temperature to be a direct one, for as the Temperature increases, so does the pressure.
                                                           
                                                                     Result

    Water      Pressure      Temp (*C)     Temp (K)    Constant(k=P/T)

     Ice           94.35           10.4                283.4                0.333
    Room       98.28           21.7                294.7                0.333
    Warm      102.46          42.0                317.0                0.323
    Boiling    110.66          79.0                352.0                0.314

How does a straw work?

As your lungs expand  the pressure inside your mouth lowers, as there is more space to occupy and not as many particles, creating a near perfect vacuum. As particles move from an area with higher pressure to an area with lower pressure, the particles inside the, lets say, juice pouch move into your mouth, as the pressure inside your mouth is less that the pressure inside the pouch. 

                         How does a Thermometer work?

As the liquid inside the thermometer is heated, thus making the particles move faster and expand, by expanding they must take up more space, therefore they travel up the tube, as there is more space there to occupy.

10/5

          This week our labs were focused on density and how we can find other variables with it. Our first lab was where we tried to measure the density of gas. The first test run,  in order to find the mass of the CO2, we measured the mass of the glass jar, the sheet of glass, and the mass of the water after its displacement (after we measured the mass of the glass jar+sheet of glass+water+CO2 we emptied the water into a beaker, of which we previously had measured the mass, and found the mass of the water) We then took the total mass of the jar, the sheet, the CO2, and water and subtracted the mass of the jar, the sheets of glass, and water to get only the CO2........ we calculated a gain in mass... we were very confused.... and our second experiment proved the same......

        We also had a quiz where we had to calculate the thickness (h) of a thin sheet of aluminum foil and a thick sheet. We knew the density of aluminum is 2.7g/1cm3. In order to find the height we used the equation m/L*W*H=2.7g/cm3....... First we measured the length and width of the thick sheet of aluminum (L=19.2cm, W=9.8cm), then we found the mass (m=1.16g) then we inserted them into the equation          1.16g/(19.2cm*9.8cm)h=2.7g/cm3        we cross multiplied and divided and came up with h=.00228cm      

      Then we took the measurements of the thin sheet of aluminum foil..... L=18.60cm, W=13.90cm, m=0.7 and density=2.7g/cm3  We inserted this data into our equation 0.71g/(18.60cm*13.90cm)h=2.7g/1cm3 and after cross multiplying and dividing got h=.00102 (we only received an 18/20in this quiz due to our confusion with significant digits)

If one substance has a greater density than another substance and they are combined, the one with the GREATER DENSITY WILL SINK (water has a density of 1g/mL)

9/28
As this is a new type of learning resource, devised from my past and future thoughts, I am going to record everything we have worked on/that I have learned/what I remember during the past couple weeks of school. The first week of school was dedicated to mass and changes in mass. We did a series of experiments: 1-We took a piece of steel wool and measured its mass. We then pulled it apart to at least double the size of the original ball and measured its mass again to see if it had changed. 2- We took an ice cube and placed it in a beaker with a watch glass over the top of the beaker (so we wouldn't lose mass through condensation), and measured its mass. After the ice cube had melted we measured it mass once again. 3- We also took a beaker 2/3 full of water and 1/8 tsp sugar and measured their mass, We then combined the two and after the sugar dissolved measured their mass once more. After all of our experiments, although there may have been changes in mass recorded, the class determined that any fluctuations were due to human error (ex: during the steel wool experiment some people didn't pull it apart over the paper letting little bits fall to the floor, consequently losing mass).

Mass and weight are not the same things. No matter where you are, your mass will stay the same (even if you are on a different planet). But, weight is determined by the amount of gravity. You could weigh 100 lbs here and weight much less on a different planet because of the amount of gravity.

 In an experiment the material in a system may change state or rearrange (physical or chemical?), but the mass stays the same until you gain particles from the surroundings.

This was displayed during an experiment. We took a ball of steel wool and held it with tongs over the Bunsen burner. Previously we had measured the mass and after we had heated it/"burnt" it we measured the mass once more. A majority of the class observed an increase in mass and we determined that because the steel wool was exposed to an uncontrolled environment during its time over the Bunsen burner particles were added/fused to the steel wool. By adding particles, we, in turn, added mass. Which led to our next revelation....

           Everything is made up of particles. Particles have mass. Mass takes up space, which means it has volume.

This last week we have touched on the meaning of density. We completed an experiment where we had two different substances, the grey and the silver. First we measured the mass of each of the different sized cylinders. We then took a graduated cylinder and filled it with water. We measured the mL of water and then slid the different sized cylinders in. We calculated the displacement each time, which was the volume of the cylinder, and recorded our data in a graph. We found that although the volume of the cylinders may be the same that the mass was greater in the silver substance than it was in the grey substance. Thus making the silver substance denser.

Density= mass/volume, density is the amount of mass for every unit of volume (mL=cm^3)

We also read an article on significant digits. We determined that you could only estimate one digit while estimating a measurement. Also that zeros can be place holders.

In making a measurement read all readable numbers using the tool and estimate 1 digit past.

We also discovered the following things through experimentation and class discussion.

Chemical Changes: A new substance is formed. The reaction gives off some form of energy: light, sound, color, and also gas (bubbles) or there's the formation of a new solid.

Physical Change: It is still the same substance (Ex: if you rip paper, it is still the same substance. The particles are just in a different arrangement)