Experiment One - Measurement (Final) Lab Report yolo

7/29/2019 Experiment One - Measurement (Final) Lab Report yolo

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Cesar Avila 1/23/13

Results:

Part A (measurements of samples to find density):

Mass (measured with electronic balance):

Dimensions of Plastic Sample (measured with Vernier calipers):

Volume (using measurements obtained from Vernier calipers):

Sample Equation for Plastic Sample 1:

V=l*w*h

2.00*1.70*1.45=4.93 cm3

V=4.93 cm3

Sample Volume (cm3)

1 4.932 7.39

3 9.86

4 12.33

Density (using measurements obtained from Vernier caliper):


=m/v6.671/4.93=1.3 g/cm3

=0.883g/cm3

Sample (g/cm3)1 1.33

2 1.37

3 1.38

4 1.37

Average Density (using measurements from Vernier calipers):

=1+2+3+4/4= 1.36 g/cm3

Sample Mass (g)

1 6.571

2 10.119

3 13.609

4 16.882

Sample Length (cm) Width (cm) Height (cm)

1 2.00 cm 1.70 cm 1.45 cm

2 3.00 cm 1.70 cm 1.45 cm

3 4.00 cm 1.70 cm 1.45 cm

4 5.00 cm 1.70 cm 1.45 cm


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Volume (using measurements obtained from graduated cylinder)


Vfinal Vinitial = Vplastic

74.3 mL-70.0 mL=4.30 mL

Sample Vinitial (mL) Vfinal (mL) Vplastic (mL)

1 70.0 74.3 4.30

2 70.0 77.2 7.20

3 70.0 79.9 9.90

4 70.0 82.0 12.00

Density (using measurements obtained from graduated cylinder):

Sample (g/mL)1 1.50

2 1.41

3 1.37

4 1.41

Average Density (using measurements from graduated cylinder):

=1+2+3+4/4= 1.42 g/mL

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Mass (g)

Volume (cm3)

Density (Vernier Caliper Measurements)

Density (Vernier Caliper Measurem


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Part B (use of density to identify unknown plastic):

Dimensions of Plastic 1 (cylinder):

Height 3.50 cmRadius (Diameter/2) 0.50 cm

Volume of Plastic 1 (cylinder):

V=r2hV=(.502)(3.50)V=2.75 cm3

Mass of Plastic 1 (cylinder): 2.298 g

Density of Plastic 1 (cylinder):

=m/v=2.298/2.75=0.836 g/cm3

Identity of Plastic 1 (cylinder): LDPE

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Mass (g)

Volume (mL)

Density (Graduated Cylinder Measurements)

Serie


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Discussion Questions:

1. Explain why significant figures are important to measurement and what theysignify.

As one of the most heavily scrutinized components of any calculation or setof data, significant figures have proved to be one of the most important

features in any numerical value given in a lab report. This importance stems

from the fact that significant figures, for the most part, determine the

accuracy of ones findings. If one were to rely primarily on calculations doneby a calculator without taking in to account of significant figures, then they

would ultimately be left with data more accurate than any of the instruments

that they used to take measurements or find certain values. Since garnering

results several degrees more accurate than measuring instruments are

capable of producing is impossible, significant figures show the correct result

to the closest known degree of accuracy. That being said, by controlling the

amount of decimal places that one can include in their results, significantfigures signify to the reader how accurately one could measure the data.

2. Of the measurements you made, which were more precise: the massmeasurements or the volume measurements?

After having completed all of the measurements necessary to determine the

density of the plastic sample it was clear that the measurements for volume

were more precise than those for mass. Since precision is defined as the

degree to which repeated measurements under unchanged circumstances

show the same results, it is impossible to measure true precision since the

samples all vary in terms of dimension and thus both volume and weight. Inorder to determine which was more relatively precise I studied the

increment of increase between sample variations:

As evidenced by the charts and the calculations for differences between

samples, the measurements for volume are more precise because they all increase in

a linear model of 2.47 cm3 per sample.

Sample Mass (g)

1 6.571

2 10.119

3 13.609

4 16.882

Sample Volume (cm3)

1 4.93

2 7.39

3 9.86

4 12.33

Difference: 2.47 cm3



Difference: 3.548 g

Difference: 3.490 g

Difference: 3.273 g


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3. Is it practical to use density to separate plastics? Explain.Although density is one of the most readily measurable properties of plastic,

it is not a very practical means of separating plastics. Since there are several

plastics that are denser than water then one could put all of the samples in a

pool of water. By doing this, one could ascertain that the plastics that havesunk have a density of over 1.0 g/mL, which would narrow the possible

plastics to very few, but not any one in particular. In order to further

separate the remaining plastics one would need to repeat the process several

times with liquids of varying densities in order to identify the plastics.

Perhaps if this were done on a small scale with readily available liquids of

varying densities then it might be pragmatic but generally speaking, it is not.

4. Propose another way to separate plastics making use of a different propertyother than density.

Since melting is one of the most integral steps in recycling, I believe that themost effective way to separate plastics would be to heat the plastics to

different temperatures to take advantage of their varying melting points. In

doing so, one would need a large-scale source of heat as well as a chart with

the melting point values for the various plastics. In order to increase

accuracy of separation, the samples would start at the lowest possible heat

and then increase according to the various melting points provided. At each

level, a different plastic will be identified until you are left with a single one.

While there are many different means of separating plastics, I believe that

this is an entirely practical way of doing so.


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Cesar Avila 1/23/13

Experiment One: Measurement

Observations:

Plastic samples all cut in same shape (rectangular prism) but differ indimensions.

Plastic samples are all proportional to one another. Exhibit a dark gray color, completely opaque. From sample to sample, the only dimension that changes is the length. This

means that there are constant values for both height and width.

Procedure:

Part A (measurements of sample to obtain density):

Linear Measurements (Vernier calipers):

1. Using the electronic balance, record the mass of each of the four samples. Record

this data.2. Using the Vernier calipers, measure the length, width, and height of each of the

four samples. Record this data.

3. Calculate the volume for each sample by inserting the measured values into the

formula V=lxwxh.

4. For each sample, divide its mass by its measured volume to obtain the density.

Graduated Cylinder:

1. Using the electronic balance, record the mass of each of the four samples. Record

this data.

2. Fill a graduated cylinder to a certain volume. Record this volume as the initial

volume or Vinitial.3. Place the plastic sample inside of the filled graduated cylinder. Record the new

volume of the water as the final volume or Vfinal.

4. Subtract the initial volume from the final volume in order to determine the

displacement of the plastic sample. This displacement will equal the volume.

5. Repeat for each sample.

6. For each sample, divide its mass by its measured volume to obtain the density.

Part B (use of density to identify unknown plastic):

1. Using the Vernier calipers, measure the height and diameter of the cylinder.

Divide the diameter in half to obtain the radius.

2. Calculate the volume of the cylinder using the formula V=r2h.3. Obtain the mass of the cylinder using the electronic balance.

4. Divide the mass by the calculated volume in order to find the density of the

sample.

5. Compare the calculated density with the literature values to determine the

identity of the sample.

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Experiment One - Measurement (Final) Lab Report yolo