Why do fizzy drinks fizz

Chemist Chuck Wight of the University of Utah provides the following explanation: Small bubbles caused by shaking help to hasten the escape of the soda's carbon dioxide. Get smart. Sign Up. Support science journalism. Knowledge awaits.

See Subscription Options Already a subscriber? Create Account See Subscription Options. Continue reading with a Scientific American subscription. Subscribe Now You may cancel at any time. A can of fizzy drink has enough gas dissolved in it to blow up a small balloon. When you open a bottle or can of fizzy drink, the pressure on the liquid suddenly gets smaller.

The drink can trap much less carbon dioxide at this pressure, so the extra gas stops being dissolved and forms bubbles. To learn more we will need to run some experiments. Pour some fizzy drink into a glass ask a grown-up first. Look at how the bubbles start where the liquid touches the glass — at the bottom and sides, but not in the middle of the drink. To make a new bubble, the molecules in the carbon dioxide and the drink move around and get organised to make a surface between them.

Less new surface needs to be made if the bubble starts against the edge of the glass. This uses less energy and means new bubbles usually start here. This is also why small bubbles tend to stick to the glass. More gas will join the small bubble, as it takes less energy to escape into a bubble to make it bigger than make a new one. Eventually, the bubble gets big enough that it will float to the top of the drink.

This happens when the bubble is still smaller than a grain of sand. When you blow through a straw to make bubbles, the same forces are acting on the bubbles as before.

But the bubble is stuck to the straw all round the edge of the hole. Irochka Dreamstime. We invite you to discuss this subject, but remember this is a public forum. Please be polite, and avoid your passions turning into contempt for others. We may delete posts that are rude or aggressive, or edit posts containing contact details or links to other websites. If you enjoyed this, why not follow a feed to find out when we have new things like it? Choose an RSS feed from the list below.

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