The Matters of the World Explained Through Science

Tuesday, December 4, 2012

A Soda Bath

 You know how you’re taught not to shake a bottle of soda before opening it? I always followed this rule, maybe because I thought I’d wake up a monster inside the bottle if I shook it before opening it, or maybe because I was just a good kid. Anyway, I decided to find out what would happen if I did shake it before opening it. And trust me, unless you enjoy having soda erupt and shower you and then have your mother scold you, I would recommend following this rule. 

There are two things you’ll have to know to know why this happens. 1.) The thing that makes soda fizzy is called carbon dioxide. Carbon dioxide or CO2, is a gas. 2.) Boyle’s Law, a scientific law discovered by a scientist names Robert Boyle, found that as long as the temperature of a gas is the same, when the pressure is increased, the gas will take up more space. When the pressure is decreased, the gas will take up less space. The amount of space something takes up is called its volume. Keep those things in mind as you read. When soda is bottled, it is also pressured. This means that the space you think is empty between the cap and the soda because the soda company is being cheap is actually filled with carbon dioxide. The carbon dioxide between the cap and soda wants to escape. When you open the cap slowly, you decrease the pressure on the carbon dioxide, and it will take up more space, or have a greater volume, and leave the bottle (remember Boyle’s Law? When pressure is decreased, the gas will take up more space). The soda itself is carbonated (fizzed up), when the carbon dioxide from the soda leaves, it creates bubbles, or fizz. However, when you shake the bottle up, you build more pressure! The carbon dioxide from the top mixes with the soda and creates more gas bubbles. When you twist the top of, the pressure in the bottle decreases and the gas expands and shoots out of the bottle. But, it also takes the soda with it! As Boyle’s Law explains, when you decrease the pressure in a bottle by taking the top off, the carbon dioxide in the bottle expands. However, if you mix the separated carbon dioxide with the carbon dioxide already in the soda, you make the soda come out with the gas that wants to escape. Bottom line? Don’t shake your soda before you open it.

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