Fizzing and Foaming
 | |  | |  | |  | |  | |  |
- 1 tablespoon of baking soda (sodium bicarbonate
- 1 tablespoon of laundry detergent
- 3/4 cup of water
- 1/4 cup of vinegar
- several drops of food coloring (optional)
- 12-ounce drinking glass
- a waterproof (plastic or metal) tray
- a teaspoon
Place the drinking glass on the tray. Put baking soda and aundry
detergent to the glass. Add water and a few drops of optional food
coloring. Gently stir the mixture to mix the contents of the glass. To
display and observe the fizzing and foaming, quickly pour the vinegar
into the glass. The mixture will foam up and over the top of the glass,
covering the tray with a froth of tiny bubbles.
To produce a color change when the vinegar is added to the mixture
in the glass, you can substitute some red cabbage juice for the
optional food coloring. The experiment titled "Exploring Acids and
Bases with Red Cabbage" gives instructions on how to prepare
some red cabbage juice. With red cabbage juice, the mixture will
chage color from blue-green before adding vinegar to red-orange
after the vinegar is added. For a different color change, try grape juice.
In this experiment, the fizz is produced by a chemical reaction
between baking soda and vinegar. Baking soda and vinegar react,
and one of the products of the reaction is carbon dioxide gas. This
gas forms bubbles that are surrounded by the liquid. The laundry
detergent makes the bubbles last longer, and a foam is produced.
The volume of the gas produced and trapped in the foam is much
greater than the glass can hold, so some of it spills over the top of the
glass.
Baking soda is sodium bicarbonate. Vinegar contains acetic acid
dissolved in water. Sodium barcarbonate reacts with most acids. The
products of the reaction with vinegar are carbon dioxide gas, sodium
acetate, and water.
The reaction of sodium bicarbonate to form carbon dioxide gas is the
basis of its use as a levening agent in baking. Cakes are solid
foams. The foam is produced when bubbles of carbon dioxide from
the reaction of sodium bicarbonate are trapped in the batter. As the
cake bakes, the batter dries, and the trapped bubbles of carbon
dioxide form the holes in the cake.
Special Thanks
Thanks to http://scifun.chem.wisc.edu for providing the experiment
instructions.