Articles

    Floaters and Sinkers

    Kids, did you ever want to make a liquid in which you could watch objects automatically swirl around? Here you will make a liquid that generates enough carbon dioxide gas to make objects float and sink. In order to make a really nice display, you will need a one-gallon glass bottle, a full 16 oz box of baking soda, water, vinegar, spaghetti, raisins, and paper clips. This is a good scale to use for a demonstration in front of a class.

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

    Pour the baking soda into the glass jar and fill about 3/4 full. Swirl to dissolve most of the baking soda and allow the rest to settle at the bottom. Add small amounts of vinegar to start the production of carbon dioxide gas bubbles. Then add several paper clips, raisins, and two-inch pieces of spaghetti and watch.

    Carbon dioxide gas collects on the surface of the objects and causes them to float to the surface. At the surface, the gas bubbles burst, the object sinks to the bottom, and the process starts again. The gas forms from the reaction of sodium bicarbonate (baking soda) with acetic acid (vinegar)

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    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    January 1993