Exploring Our Fluid Earth

Use your powers of observation, investigation, and scientific thinking to figure out why some soda cans float and some sink.

• A variety of 12 oz. canned sodas
• Fresh water
• Bucket or other large container
• Scale
• Calculator
• Towels
• Small container (optional)
• Salt (optional)
• Graduated cylinder (optional)

1. Observe the soda can demonstration. Record your observations.
2. Examine your soda cans for variables that potentially affect soda can sinking and floating.
   
   1. To help you develop your list, look at the similarities and differences between the regular sodas. Then look at the similarities and differences between the diet sodas.
   2. Develop a list of at least three variables that might affect soda can sinking and floating record and record these in Table 1.1.
   3. For each variable make a prediction as to how the variable affects the sinking and floating of soda cans.  Record your prediction in Table 1.1.
   4. For each variable explain your prediction in Table 1.1.

3. Using your list of soda can variables, develop a hypothesis for the observed floating and sinking of the demonstration cans. Record your hypothesis in your notebook.
4. Transfer your list of soda can variables from Table 1.1 to Table 1.2. Note: these should be variables that you can quantify or test using the materials available.
5. Generalize the hypothesis you developed in procedure 3 to apply to all soda cans. Predict which of your cans will sink and which will float. Record your predictions in Table 1.2.
6. Test your hypothesis. Record your observations in Table 1.2.

3. Determine the density of each of your cans.
   1. Weigh each can–dry it off first–to the nearest tenth of a gram. Record in Table 1.1.
   2. The volume of the liquid in each can is 12 oz, or 355 mL. The total volume of the can is approximately 380 mL. (Optional: you can determine each soda can’s exact volume by using a graduated cylinder.)
   3. Calculate the density in g/mL of each type of soda by dividing the mass by the volume.
4. Based on your observations of your soda cans sinking and floating, review how the variables you chose affected sinking and floating. Return to Table 1.1 and summarize your observations in the last column. Note: it may be helpful to look at 
   the variable columns in Table 1.2.
5. Optional: Based on what you know about density, floating, and sinking, how could you make one of your sinking cans float? Design an experiment using only the materials provided by your teacher to do the following:
   1. Make a can of soda float in mid-water in a small container.
   2. Make a can of soda float above water in a small container.