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Dissolving Packing Peanuts

4.4 based on 14 ratings

Updated on May 01, 2014

Sometimes the best part of a package is the packing peanuts! They’re the inch-long, puffy pieces that protect fragile things like pictures frames and cups from breaking when they are shipped long distances. There are two kinds of packing peanuts: those made of starch, which is easy to break down, and those made of polystyrene, which is hard to break down.

For this experiment, you need to use starch packing peanuts. Starch is made from plant material mixed with lots of carbon dioxide, the same stuff that makes the bubbles in soda pop. The plant material exists as a solid, while the carbon dioxide is a clear gas that has no smell. The texture of packing peanuts might feel familiar to you because many puffy breakfast cereals are made the same way packing peanuts are!

Packing peanuts do an important job, but they take up a lot of space after the box arrives. People and businesses who get a lot of things shipped to them need to a way to get rid of their packing peanuts without filling up their garbage cans. Luckily, there are many ways to break down starch packing peanuts. Your job is to find the best one.

Problem: What substances break down starch packing peanuts the fastest?

Materials:

  • 8 equally sized starch packing peanuts
  • Metric ruler
  • 8 clean cups or glasses
  • Water
  • ¼ cup measuring spoon
  • Stove or microwave
  • Ice cubes
  • 8 spoons
  • Sugar
  • Salt
  • Vegetable oil
  • Vinegar
  • Any other substances you are interested in testing
  • Clock

Procedure

  1. First, set up a data table that looks something like this. Fill in items 7 and 8 in the column labeled “treatment” with the names of the treatments of your choice.

Treatment

Length before

Width before

Length after

Width after

Observations

1.Room temp water

  1. Ice water

  1. Hot water

  1. Salt water

  1. Sugary water

  1. Oil

Your choice

Your choice

  1. Using the ruler, carefully measure the length and width of a single packing peanut in centimeters. Record your measurement in the “before” column of your data table. Your peanuts should be about the same.
  2. Next, set up the treatments for the peanuts.
    1. Put ¼ cup of room temperature water in the first cup.
    2. In the second cup, add a couple ice cubes to ¼ cup water.
    3. For the third cup, have a grown up help you warm ¼ cup water on the stove or in the microwave.
    4. Pour ¼ cup of water in the fourth cup and add enough salt to make a saturated solution. A saturated solution contains as much dissolved material it can at a certain temperature. You can tell you have added enough salt to make a saturated solution when some salt remains on the bottom of the cup even when you stir it.
    5. Pour ¼ cup of water in the fifth cup and add enough sugar to make another saturated solution.
    6. Measure ¼ cup of oil into the sixth cup.
    7. Set up the treatments of your choice for the next two cups (or you might want to save testing these for a second round, after you have seen the results of your first experiment).
  3. Make a hypothesis about which treatment you think will break down the peanut fastest. What is your reasoning behind the hypothesis you made?
  4. Make sure there is a spoon in each cup, and add a starch peanut to each. Why do you want to add all of the peanuts at the same time?
  5. Stir all of the peanuts in their cups. You might note that the peanuts float better in some treatments than they do in others. Make sure to dribble some the liquid over the peanut to ensure that the whole peanut is covered.
  6. Continue stirring and observing for ten minutes.
  7. Remove the peanuts from the treatments at the same time, and place each beside its cup.
  8. Measure the length and width of each peanut, and record these measurements in your data table. Take any notes about peanut texture in your observation column.

Results

Your results will vary depending on the exact type of packing peanuts you used. The packing peanut in room temperature water will get shorter and less wide, and it is likely to feel slimier and less puffy. The packing peanut in ice water is likely to change less, while the packing peanut in hot water is likely to get smaller. The peanuts in the salt water and oil are likely not change much in size or texture, but the one in sugar will change more.

Of course, what happens in your choice cups depends on the treatments you chose.

Why?

The starch in the peanuts dissolves in water. When a substance dissolves, it breaks into very small pieces in the solvent (often a liquid) that is dissolving it. When the starch dissolves, it allows the carbon dioxide within the peanut to escape into the air, making the peanut much smaller and slimier.

Heating the water causes its molecules to move around faster, speeding up the dissolving process. Cooling the water slows down the dissolving process. Because the salt water already has so much salt dissolved in it, there’s not much room left in the solvent for starch molecules, so the peanut didn’t break down as much. The sugar solution also does not have much room for the starch, but since the sugar and starch are very similar, it is easier for the starch to dissolve in a sugar water solution. Because oil is not a good solvent for dissolving starch, the peanut does not break down much in oil at all.

Going Further

If you want, you can repeat your experiment using polystyrene peanuts. You will probably be a bit frustrated with how little they change, so you may want to ask a grown-up to measure out and test ¼ cup of nail polish remover. It will break down Styrofoam peanuts, but can be dangerous if inhaled!

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