Lab: Density Experiment #1: Density of Plastic Blocks Materials • 4 Plastic blocks (2 different colors and 2 the same color but different sizes) • Metric ruler, 0.1 em markings • Balance • Calculator Procedure Experiment #1: 1. Record the plastic block numbers and colors in data table 1. Color choices include the following: white, black, milky-white, clear, and gray. 2. Use the laboratory balance to measure the mass of each block (in grams). Record the mass in data table 1. 3. Use the metric ruler to measure the length, width, and height of each block (in centimeters). Record the measurements in data table 1. 4. Calculate the volume of each block (in crrr') using the following equation: Volume
= Length
x Width x Height
Record the volume in data table 1. 5. Calculate the density of each block (in g/cnr') using the following equation: Density = Mass Volume Record the density in data table 1. 6. Complete the Analysis and Conclusion questions. Data Table 1
Block Number Color of Block Mass (g) Length (em) Width (em) Height (em) Volume (ern") Density (g/cnr')
Analysis Experiment #1 1. What are the densities of the blocks that were the same color, but different sizes? Were they the . same or different? Explain your results. Block color = ----Block number
density =
_
Block number
density
=
_
Explain:
2. Select one of your other blocks and record its number and density below. If this block were cut into two equal pieces, what would be the density of each piece? Explain your answer. Block number = Block density = Density of each piece =
_
Explain:
3. Obtain the actual density of each colored block from your instructor. Determine the accuracy (percent error) of your calculated densities by comparing them to the actual densities using the following equation: Percent Error
=I
I x 100
Calculated Density - Actual Density Actual Density
Block Number -----
Actual Density
_
Block Number -----
Actual Density
_
Block Number -----
Actual Density
_
Block Number -----
Actual Density
_
Experiment #2: Density of Irregular Objects Materials • 3 different irregular objects (marble, cylinder, and small rock) • Graduated cylinder • Balance • Calculator • Beaker (with water) • Plastic spoon Procedure Experiment #2 1. Use the laboratory balance to measure the mass of each irregular object (in grams). Record the mass in data table 2. 2. "Fill the graduated cylinder part-way with water (fill at least high enough to let the irregular object to submerge when placed inside). Record this volume (in mL) in data table 2 as the first water level. HINT: To make reading easier, try to fill the graduated cylinder to an even number divisible by 10 (i.e. 20 mL, 40 mL, etc ...). 3. CAREFULLY drop an irregular object into the graduated cylinder by tipping the graduated cylinder slightly and allowing the object to slide down (BE CAREFUL NOT to spill any water). Record this new volume (in mL) in data table 2 as the second water level. 4. You are going to determine the volume of your irregular shaped object by water displacement using the following equation: Volume of Irregular Object = Second Water Level Volume - First Water Level Volume Record this volume (in mL) in data table 2 as volume of object. 5. Repeat the above procedure for the other two irregular objects. 6. Calculate the density of each irregular object (in g/cnr') using the following equation: Density =
Mass Volume of Irregular object Record the density in data table 2. 7. Complete the Analysis and Conclusion questions. Data Table 2
Object Mass (g) First Water Level Volume (mL) Second Water Level Volume (mL) Volume of Irregular Object (mL) I
Density (g/cm")
Marble
Cylinder
Rock
Analysis Experiment #2 1. Which of the irregular objects is made of the densest material?
2. Could this method (water displacement) be used to determine the volume and density of a small rectangular or square shaped object? Explain.
3. If a rock with a density of 10 g/crrr' is broken into five equal pieces, what is the density of each piece? Explain your answer.
Conclusions: 1. Why is the density of a substance important? Explain your answer in 3 - 4 sentences.
2. What state standards did you cover in this lab?
Conclusion: 1) What is the difference between accuracy and precision?
2) Which method of calculating the volume do you think is more accurate? Why?
3) When is it advantageous to use a graduated cylinder to measure volume?
