Science of fizz
There’s something about fizz that just makes any drink more fun. Champagne feels so much more exciting than regular old wine, and I don’t know anyone who wants to drink a flat soda. Bubbles feel like magic.
So how do we harness this magic of carbonation? It’s all about carbon dioxide. By itself, it’s not very remarkable: you’re breathing it in and out right now (it makes up less than 1% of air), and if you’ve read anything about global warming you’ve seen graphs charting its concentration in the atmosphere. This same gas forms the bubbles that fizz and pop in your mouth to make Perrier classier than tap water.
It seems a little strange to talk about a gas trapped in water, but it’s just like dissolving sugar into hot coffee. In the same way that the liquid (coffee) holds onto the solid (sugar), it can also hold onto gases like carbon dioxide. Using a cylinder of compressed carbon dioxide, you shoot the gas into your beverage of choice and quickly seal it up. This seal is very important, as anyone who has opened a bottle of carbonated soda can attest. The liquid looks still and calm beforehand, the gas quietly laying in wait for its opportunity to make a break for it. As soon as you crack the top, though, the carbon dioxide seizes its chance and makes a mad dash for the top, leaving trails of bubbles up the sides and fizzling and popping on the surface.
The reason behind this intense reaction to the top opening stems from a principle that humans follow just as much as carbon dioxide: if we feel crowded, we move toward open space. We can shoot carbon dioxide into water and it will hang out there, but only for a little while. The water is full of lots of gas molecules, crowded together like a downtown highrise, and they can see the greener pastures of free air at the top of the bottle. We can understand why the gas moves toward the area where it has more space, which we see as bubbles escaping. Why doesn’t this happen before you open your soda? The empty space at the top of the bottle isn’t really empty at all. It’s filled with a high concentration of carbon dioxide so that the gas sees the same amount of crowding everywhere in its world.
So the next time you open a bottle of champagne or make some delicious sparkling ginger lemonade, you can see the bubbles with new eyes. They’re not just the fizz that tickles your nose and feels like you’re drinking sparkles, they’re trapped carbon dioxide molecules making a break for it. Your thirst has granted them freedom. Cheers.
Science from America’s Test Kitchen. Check out the video for more!