The soda will fizz as a result of the unstable or meta-stable state where CO₂ escape from water or the solution. When you shake the soda, you will input energy into the system and also disrupt the meta-stable state, allowing CO₂ to escape much more easily.

So why does CO₂ escape from the water? Normally the water will only dissolve a very limited amount of CO₂. The soft drink manufacturer intentionally put a lot more CO₂ into water by applying high pressure at relative low temperature. When the condition is back to normal, the excessive CO₂ will escape from the cage.

What an exciting question! Soda is fizzy because the gas inside the soda liquid is trying to escape. You might notice that if you open a soda and leave it out for a long time, you don't have the same fizz as when you just opened it. This is because all of the gas has escaped the liquid. When you shake the bottle before its opened, you make it much easier for the gas to escape the liquid faster. The gas builds up pressure inside the bottle like blowing up a balloon, and opening the soda is similar to popping the balloon. This results in the fizz! I hope this explanation helps to answer your question!

This is a really fun question because it shows us a lot of really interesting science in a completely normal environment. The soda companies add gas to sodas because people like the fizziness of the drink. The gas that they add is called carbon dioxide and it is the same gas that all of us exhale. The soda companies add this gas to the soda and over time, the gas will try to escape. This is what you’re seeing when you watch bubbles rise out of your soda—carbon dioxide leaving the drink. When you shake a soda, the liquid loses its grip on carbon dioxide and it is able to escape much quicker than normal. The gas leaves as bubbles which appear as fizziness. A fun follow up question might be: how come a soda explodes if you shake it too much? The same principle is at play here—gas leaving the soda more quickly than it normally does. The only difference is that if you shake a soda, a ton of the gas tries to escape all at once and the pressure causes the soda explode out when opened. Thank you for the question!