Chemical yo-yo

Make drops of vinegar fly up and down!


- vinegar,
- oil,
- baking soda,
- a glass or jar.


At the bottom of the glass pour baking soda layer ( about 1 cm. thickness). Soda should not be on the walls.

Then, pour the oil into a container. Get him carefully down the side of the glass, taking care to not mixed with the baking soda. The glass should be filled almost completely.

Add to the oil a few large drops of vinegar.

Vinegar drops fall to the bottom of the glass, where they contact with the baking soda. Around this drops the gas forms bubbles that float up drops. When the gas detach from the vinegar bubbles surface, drops fall to the bottom again.

If the experiment is carried out accurately, drops wander up and down like a yo-yo.


Vinegar is an aqueous solution of acetic acid, CH3COOH. Soda is sodium bicarbonate, NaHCO3. Vinegar has a higher density than the oil, thats why it sinks in the glass. When it touches the surface of the soda, comes the reaction:

acetic acid + sodium bicarbonate -> sodium acetate + carbonic acid

The stronger acetic acid displaces carbonic acid from its salt. Carbonic acid in the aqueous solution reacts rapidly in decomposition reaction:

H2CO3 -> H2O + CO2

In the reaction of the soda and vinegar the main product is carbon oxide (IV). Gas is lighter than oil and it floats to the top and takes acetic bubbles with -transports them to the surface. Later only gas can dissolve in the air. Deprived of gas vinegar sinks to the bottom, where initiates another reaction. After some time (and many contacts with soda) vinegar loses its acidity. The reaction stops and drops stay on the bottom.