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PERFORMANCE
ASSIGNMENT Lab Three |
So far you have determined how to use many laboratory instruments and make proper observations of physical and chemical change. In this laboratory you will use those skills to properly identify specific compounds using density. Density is an intensive property as it does not depend on the amount of material measured. A kilogram of lead has the same density as a gram of lead. Properties such as mass and volume are known as extensive properties as they depend on the amount of matter.
Objectives:
1.
Identify and use appropriate pieces of equipment to make observations.
2.
Evaluate laboratory results and draw conclusions.
Procedure:
1.
Use a balance to determine the mass of several samples of unknown
material. Record the information.
2.
Measure in 15 ml of water into the graduated cylinder.
3.
Submerge the unknown material into the graduated cylinder and record
the increase level in the graduated cylinder.
4.
Subtract the beginning volume from the ending volume and record.
5.
Calculate the density of the unknown by dividing the mass by the
volume.
6.
Identify the unknown and record its true density.
7.
Calculate the error in measurement by dividing the observed value by
the known value and multiplying by 100%.
Observations:
|
Unknown # |
mass |
Initial Volume |
Final Volume |
Volume of Unknown |
Density |
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Synthesis:
1.
Using a table of known densities, identify the name of the unknowns.
2.
Record the true values of the density
Calculations:
1.
Calculate the error of the
observed density.
2.
What are three reasons that
might account for the amount of error?