Why do carbon dioxide bubbles rise

Carbon dioxide is the gas responsible for the fizz in fizzy drinks. You feel this pressure being released when you open a fresh bottle of pop. Then you pour your fizzy drink into a glass. The high pressure that was once holding the carbon dioxide in the liquid is now gone.

There is more carbon dioxide in the drink than the drink can hold so the carbon dioxide comes out as bubbles. Instead of instantly bubbling out of the drink the gas bubbles out quite slowly at the bottom and sides of the glass. This is because bubbles are not easy to make. You can think of it like this, the little carbon dioxide molecules want to get out of the drink but they need a few of them to get together and make a bubble before they can escape.

The bottom and sides of the glass have tiny little imperfections on them, microscopic dents and scratches. There is already a tiny bubble of gas trapped in these imperfections. When a carbon dioxide molecule collides with this bubble they merge making a bubble that is too big for the scratch or dent to hold. So the bubble breaks in half, some of it stays behind and some of it floats up to the surface and pops.

Because some of it stays behind the same thing can keep happening over and over again. This is why you see a stream of little bubbles coming from certain points on the glass.

Some glasses are actually designed to have these little scratches to make more bubbles. Pour yourself a glass of something fizzy and leave it undisturbed. Do the bubbles ever stop? How long does it take?

If so, can you think of a way to speed up or slow down the process? Thank you for your question, Alison! First of all, we have to know where the bubbles in the fizzy drink come from. This happens because they have a gas called carbon dioxide dissolved in them. The gas and the liquid and everything else are made up of tiny bits of stuff called molecules. When the gas dissolves in the liquid, the molecules mix together really well so that the gas gets trapped without there being any bubbles.

The amount of gas you can dissolve into the liquid depends on how much pressure it is under. When the pressure is high, it is like there is a lot of weight pushing the gas into the liquid, so lots of it can dissolve. To make a fizzy drink, carbon dioxide is bubbled through liquid at a pressure that is five times greater than the normal pressure we live at. We would feel the same amount of pressure if we swam to the bottom of a swimming pool that was 50 metres deep 50 metres is about eight giraffes standing on top of each other.

Curious Kids is a series by The Conversation , which gives children the chance to have their questions about the world answered by experts. This is how so much gas is trapped.

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. Yakun Chen, Ji Lv and Kaixin Ren wanted to see how drink additives such as sugar, salt and added flavors affect the carbon dioxide and ultimately, the taste of the drink. The team studied how different flavorings affected the carbon dioxide in champagnes, cola drinks and club sodas by setting up simulations. The group first examined how fast carbon dioxide diffused within each solution. They found that additives like alcohol, table sugar or baking soda would reduce the rate of diffusion, to an extent, which would leave soda fizzy for a longer period of time.

The researchers also noted that the simulations showed that as carbon dioxide interacts with additives like sugar, it also interacts with the water that makes up the majority of these beverages. When a drink additive was incorporated, the team noticed that the number of hydrogen bonds decreased with their simulation, ultimately impacting the taste of the drink. Note: ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Careers Launch and grow your career with career services and resources.

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