Experiment 1

 Measurement and Density

Objectives:

To (1) become familiar with measurement devices commonly used in scientific work, and (2) to measure the mass densities of a few selected objects

 Equipment:

 A metric ruler, a Vernier caliper, a micrometer, a mass balance, a few regularly shaped solids, and a scientific calculator

Theory: 

           Measuring instruments have limited precisions that must be considered during use.  These limited precisions will result in the transmission and compounding of errors if the correct significant figures are not applied to calculations.  The student should have an understanding of significant figures prior to this experiment.

 Mass density is defined as the mass per unit volume.  gm/cm3 is, therefore, a unit of mass density.  The mass density of an object may be found by dividing its mass by its volume.

Formulas used in the calculation of volume (V) are:

Rectangular block or cube:  V = length x width x height  = LWH

                                         Sphere:  V = (4/3) π R3

                           Cylinder:  V = π R2L

Mass densities of a few substances are given below:

Table 1

Aluminum     2.7 gm/cm3 Ice        0.9 gm/cm3  Brass      8.6 gm/cm3
Concrete      2.3 gm/cm3 Iron      7.8 gm/cm3  Lead     11.3 gm/cm3
Copper         8.9 gm/cm3 Steel     7.8 gm/cm3 Gold     19.3 gm/cm3

Procedure:

  1. Record the sensitivity and zero reading of each measuring device on the data sheet (See the chart under Data).
  2.  Obtain the necessary measurements to calculate the volume of each object with the specified measuring device. 
  3. Record the readings to the correct number of significant figures on the data sheet.  Always estimate between smallest graduations.
  4. Determine the masses by weighing them on the mass scale (triple-beam balance).
  5. Calculate the average values to be used in determining the volume and mass.
  6. Calculate the volume and mass density for each measured object and display these values in a clearly labeled table of results.
  7. Calculate a percent error on the density of each item.

Data:

Given: The accepted values for the densities of the metals used (See Table 1 above).

Measured:

Device

Sensitivity

Zero

Vernier Caliper

    

Micrometer

    

Triple-beam Balance

    

 

I)  Aluminum rectangular block (Use a Vernier caliper)

Trial Length Width Thickness Mass
1        
2        
3        
Average        

II.                                       

II) Steel sphere (use a micrometer)

Trial Diameter (cm) Mass (gram)
1    
2    
3    
Average    

 

Calculation(s):

 

    Provide the necessary calculations.

Comparison of the results: 

     Provide the percent error formula used as well as the calculation of the percent errors.

Conclusion: 

     State your conclusions of the experiment.

Discussion: