It’s unavoidable that soda bottles or cans are moved around in shopping bags, or fall down on their side and roll on the floor or ground. Or it may be because some pranksters think it’s funny to see a soda bottle or can explode in your face. During these times, it’s safer not to immediately open the soda or else you’d get wet from the exploding foam. But why does shaken soda explode? Here’s a brief explanation.

Carbon dioxide in soda

Carbonated soda is essentially water containing dissolved carbon dioxide gas. During processing, the bottlers pressurize the bottle before filling it up with carbonated soda. The volume of pressurized air inside the bottle is twice as much as the air outside the bottle.

As a result, the gasĀ  inside the bottle continuously moves from the bubbles escaping the liquid to gas particles sticking against the inside surface of the bottle, and then moving back again into the soda.

Eventually, the gas molecules achieve a state of equilibrium after bottling, and later on, when left untouched on the shelf or in the fridge. Since the bottle is in a state of relative rest, the pressure is the same all over, so no bubbles can form.

Soda Can Explode Why Does Shaken Soda Explode?

The pressure does not increase

We think the pressure inside the bottle increases when shaken and causes the soda to explode, but this is not true. Something else causes the eruption of the foam. The shaking creates little whirlpools inside the bottle. The pressure towards the center of the soda whirlpools is smaller than the surrounding soda pressure, so bubbles develop.

When we start uncapping a bottle or opening the top from a soda can, bubbles will have formed in the whirlpool eddies created from shaking. Take the cap off, and the bottle pressure drops. The bottle still contains whirlpools from the shaking as more and more bubbles of air form. The pressure inside the microscopic bubbles is roughly twice the surrounding liquid’s pressure. The tiny bubbles, therefore, explode in size.

As the bubbles explode, air inside is released. More and more gas particles exist inside the bottle than liquid particles. They have no way to go, but up. And, as they push on to get out, they push the liquid out along with them. And then the soda explodes!

How not to get wet

Opening a bottle is easy. It doesn’t matter that it may have been shaken either deliberately by worthless pranksters, or accidentally while being transported from the store to at home. All we need to do is release the gas first by slowly opening the bottle cap. When you hear the soft hiss of air escaping the bottle, you’ll know it’s safe to open the cap all the way.

In the case of a soda can that’s been moved or shaken, snap the side of the can with your fingers first to settle the bubbles down to the bottom of the can before pulling the top off the can. The opening of the can must be facing away from you while you do this.

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Categories: Beverages

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