Evidence of a Chemical Reaction

In the classic grade school volcano, the baking soda (which is sodium bicarbonate) reacts with acetic acid in the vinegar to form carbon dioxide gas, water, and sodium acetate.
The newly formed carbon dioxide bubbles out of the mixture, causing the eruption.
Reactions that occur in liquids and form a gas are gas evolution reactions.
Red food coloring helps us see the bubbles.

In the classic grade school volcano, the baking soda (which is sodium bicarbonate) reacts with acetic acid in the vinegar to form carbon dioxide gas, water, and sodium acetate.