What happens when you mix baking soda and vinegar in a bottle with the top on?

When you mix baking soda (sodium bicarbonate) and vinegar (acetic acid) in a closed container, the following chemical reaction occurs:

NaHCO3 (sodium bicarbonate) + CH3COOH (vinegar) -> CO2 (carbon dioxide) + H2O (water) + NaCH3COO (sodium acetate)

This reaction produces carbon dioxide gas, which is trapped in the bottle since it can't escape. The buildup of gas creates a lot of pressure inside the container. If the pressure becomes too great, it can cause the bottle to burst or explode.

The resulting chemical reaction creates a lot of fizzing and bubbling, and a lot of pressure is built up inside the bottle as the carbon dioxide gas is produced. This can cause the bottle to become very hard and difficult to open. If the pressure is not released, the bottle may eventually explode.