Final answer:
Baking soda reacts with vinegar because it is a base and vinegar contains acetic acid. This reaction produces carbon dioxide gas, causing the bubbling and foaming.
Step-by-step explanation:
When baking soda is mixed with water, it does not produce any bubbles. However, when baking soda is mixed with vinegar, it rapidly bubbles and foams. This scenario demonstrates the chemical property of baking soda reacting with an acid. Baking soda (sodium bicarbonate) acts as a base and reacts with the acetic acid in vinegar to produce carbon dioxide gas, which is responsible for the bubbling and foaming.