Physics
Vandebilt Catholic High School
Walt Dupre

Lab: Density

PURPOSE:    The purpose of this lab is to utilize proper measuring technique to measure the mass, and volume of four unknown solids. These measurements will be used to calculate the density of each solid. The results obtained will be compared to a list of acccepted density values in order to identify the substances.

CONCEPTS:    Fundamental and derived units, the metric system, measuring skills, accuracy, and precision, significant digits.

MATERIALS:    List all materials used to complete the lab using the proper format.

PROCEDURE:

  1. Select a metal cylinder and use the balance to measure the mass of the metal sample. Report your answer in grams (g) and use the proper number of significant digits.
  2. Use the metric ruler to measure the length of the metal cylinder. Report your answer in centimeters (cm) nd use the correct number of significant digits.
  3. Use the micrometer to measure the diameter of the metal cylinder. Report your answer in centimeters (cm) nd use the correct number of significant digits.
  4. Caluculate the cylinder's volume in cubic centimeters (cm3). Formula: V = pr2l
    where;"r" = radius and "l" = length.
  5. Calculate the cylinder's density in grams per cubic centimeter (g/cm3). Formula: r = m/V
    where; "r" = density, "m" = mass, and "V" = Volume.
  6. Identify the metal sample by comparing your calculated value for density with the accepted values posted throughout the room.
  7. Determine the accuracy of your results by calculating the percent error (ER).
  8. Repeat steps 1 - 6 for the other metal cylinders given.

DATA:    Complete a data table that resembles the following.

Sample

Mass (g)

Length (cm)

Diameter (cm)

Radius (cm)

Volume (cm3)

Density (g/cm3)

Type of Metal

Accepted Density (g/cm3)

Relative Error (ER)

1

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

3

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

SAMPLE CALCULATIONS:    Provide one example of the volume of the cylinder was calculated and one example of how the density was calculated.

ERROR ANALYSIS:

  1. Show one example of how the relative error was calculated.
  2. Statement of acceptability of your results.
  3. List possible reasons for error

CONCLUSIONS:    Discuss results as they relate to the purpose of the lab and the concepts covered in the lab.

QUESTIONS:

  1. What quantities and units used in this lab are fundamental and which are derived?
  2. How many significant digits are in each measurement in the column for mass, length, diameter, radius, volume, and density? Explain why there are different numbers of significant digits in the different columns.
  3. What is the difference between accuracy and precision? How does each play a part in this lab?
  4. Describe another method you could have used to determine the volume of the metal cylinders.

    5. Densities of Selected Substances

    Substance

    density (g/cm3)

    aluminum

    2.699 g/cm3

    zinc

    7.19 g/cm3

    tin

    7.30 g/cm3

    iron

    7.60 - 7.90 g/cm3

    brass

    8.44 g/cm3

    copper

    8.89 g/cm3

    lead

    11.347 g/cm3

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