Summary: Small pieces of spaghetti are added to a solution of baking soda and water. The addition of vinegar then makes the spaghetti "dance".

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Estimated Time: 15 - 20 minutes

Materials Needed:

• 1 tall, clear 12-oz (360 mL) plastic cup or tall, glass beaker
• 1 tsp baking soda (4g sodium bicarbonate)
• 2 tbsp vinegar (30 ml of 3% acetic acid)
• 4-5 large pieces of angel hair pasta (spaghetti)
• 1 spoon
• tap water

Safety Notes: It is not recommended for anyone to drink the solution. Never drink anything out of a beaker. If using glass beakers, make sure participants are aware of how to safely handle glass.

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Introduction: In the balloon activity, you were able to catch carbon dioxide and show it to someone. Now we are going to learn a little bit more about carbon dioxide. How did we make carbon dioxide in the last activity? We made it by mixing vinegar and baking soda. We will use the same reaction again in this activity.

Procedure:

• Fill the plastic cup 2/3 full with tap water.
• Add 1 teaspoon of baking soda to the water. Stir to dissolve.
  • What does the water look like when you add the baking soda?
  • What about after it dissolves?
• Break the spaghetti into small pieces (less than 1/2 inch). Put all of the spaghetti into the cup. Stir. Observe your cup.
  • Is the spaghetti doing anything?
  • Where is the spaghetti? Why?
    
• Take the spoon out of the cup and set it aside. Add 2 tablespoons of vinegar to the cup. Watch!
  • What is happening to the spaghetti? The spaghetti should be "dancing" in your cup and moving up and down. If not, add a little more vinegar. If needed, add more of both ingredients.
  • What else do you see occurring in the water? Why do you think this is happening?
  • Have you seen this before? Where?
  • Why does your spaghetti rise and sink?

  
  **When cleaning up, do not discard spaghetti into sink drains as it may cause clogging.

Think About It:

Elementary Level:

At the beginning of the experiment the spaghetti sinks to the bottom of the cup because it is "heavier" than water. However, things change when the vinegar is added to the water. There is actually a chemical reaction occurring in the water.

Baking soda is a chemical called sodium bicarbonate and it reacts with vinegar. Vinegar is called acetic acid. These two chemicals react and form something new. This new stuff is inside of the bubbles in the water. What do you think it is? That's right, carbon dioxide. Remember, carbon dioxide is a gas. Where else have you seen this kind of bubbles? Soda also has bubbles like this.

The noodles sink to the bottom of the water. Why? The spaghetti is "heavier" than water. We say that the spaghetti is more dense than the water. What about the bubbles? The bubbles rise in water. What does this tell you about carbon dioxide? Is carbon dioxide gas more or less dense than water? It is less dense.

The bubbles of carbon dioxide attach to the spaghetti pieces and make the spaghetti noodles float to the top of the cup. It's just like the spaghetti has its own life jacket. But what happens when the bubbles reach the top of the water? The bubbles pop. The noodles cannot float with out the bubbles because they are too heavy. The noodles fall back down until more bubbles attach to it.

Middle/High School Level:

Vinegar (HC₂H₃O₂) is a solution of acetic acid. It reacts with baking soda, sodium bicarbonate (NaHCO₃), to produce carbon dioxide gas (CO₂) and an aqueous solution of sodium acetate (NaC₂H₃O₂). The reaction can be written as follows:

NaHCO₃ (aq) + HC₂H₃O₂ (aq) ------> CO₂ (g) + H₂O (l) + NaC₂H₃O₂ (aq)

Bubbles of carbon dioxide gas attach to the surface of the spaghetti. The result is that the density of the spaghetti and the gas is less than that of the water solution, so the pieces rise to the surface. Many of the bubbles "pop" at the surface and the density is once again greater than that of the water, so the spaghetti sinks. Children's "water wings" operate on the same principle by increasing the volume of the child without increasing the mass considerably.

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Teaching Tips:

• Typically we have students complete this activity in groups of 2-4. The baking soda and vinegar fit nicely into 2-oz plastic cups. You can get these at school supply stores, craft stores or food stores. The containers we use are called ramekins and come with plastic lids. These are great because things can be portioned ahead of time and stacked. We recommend that you pre-measure ingredients for young students.
• The amounts of baking soda and vinegar are approximate and depend on the cup/beaker used. If a large container is used, increase the amounts of baking soda and vinegar.
• A drop of food coloring can be added to the water to enhance spaghetti "dancing" movement.
• Raisins can be used in addition to, or in place of, the spaghetti.
• Make sure to get angel hair pasta and not thin spaghetti. The thin spaghetti is still too dense.
• When disposing, remember to make provisions for solids to be placed in the trash instead of sinks. We have found that using a mesh screen placed over the drain is the most effective. Spaghetti pieces will clog drains!