Name:Density and Buoyancy

Background: Density is a relationship between an object’s mass and its volume. Mass is measured with a ______in units of ______. Volume is measured with a ______in units of ______. The formula for density is and the unit for density is g/mL or grams per milliliter.

Hypothesis: Circle the materials that you think will sink in water:

zincaluminum steel plastic cubepencil

Procedure: You will measure the mass and volumes of five materials and determine their densities. You will then compare these values and how the materials behave to the idea of buoyancy. Buoyancy is a measure of the upward force a fluid exerts on an object.

  1. Mass each material and record the values in your data table with the unit grams.
  2. Use the water displacement method to find the volume and record it in mL.
  3. Compute the density of each material using the formula.
  4. Did the material sink or float?

Observations:

Material / Mass (g) / Volume (mL) / Density (g/mL) / Sink or float?
Zinc
Aluminum
Steel
Pencil
Plastic Cube

Water Displacement Table:

Zinc / Aluminum / Steel / Pencil / Plastic Cube
Initial Volume of Water
Final Volume of Water
Volume of Material

Calculating Density of an Unknown:

1. Obtain an unknown piece of metal from instructor. Use a balance and water displacement to find the mass and volume of the metal. Calculate density.

Material / Mass (g) / Volume (mL) / Density (g/mL) / Sink or float?
Unknown Metal

Conclusion Questions:

1. Use the density calculated for the unknown metal to determine the identity of the metal. Circle your answer.

Aluminum Density=2.7g/mLCopper Density=8.9g/mLIron Density 7.9g/mL

2. Did all the materials have the same density? _____ Why or why not?

3. Which materials sank? ______Did this match your hypothesis? ______Why do you think these materials sank and the others did not?

4. How do you think the material an object is made of might affect its buoyancy?

5. Calculate the density of a rock if the mass if 25.6g and the volume is 4.5mL. Show work.

6. Calculate the density of a liquid if the mass if 87.7g and the volume is 80.2mL. Show work.

7. Design your own experiment to calculate the density of vinegar (a liquid). Use the space below to write your procedures and to draw a data table. Carry out your experiment.