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Question: Why is it when you shake soda bubbles form?
The bubble formation when you shake a soda is due to a process called 'nucleation and growth' which happens as the molecules that make up the soda separate during the shaking.
To see how this works let's say that the soda is made up of three different kinds of molecules: It is also important to understand that to get the carbonation molecules into the mix they are 'forced' by using a high pressure (usually twice the pressure of the atmosphere). In those spaces the lower pressure attracts the carbonation molecules from the surrounding mixture so that some of the carbonation molecules get together into 'clusters' of very tiny spherical bubbles.
As the sloshing of the 'flavor', water and carbonation molecules moves them back and forth the smaller 'clusters' get swept away and re-mix into the soda assisted by the higher pressure of the mix.
Also causing the 'cluster' bubbles to collapse is the high pressure in the soda container, which as we said earlier is about twice the pressure of the atmosphere outside the container. The 'rule of thumb' for how pressure affects the bubble collapse is that the larger bubbles are, the more they resist pressure, which causes collapse. With that lower pressure available the bubbles are now able to rapidly grow and escape the container giving the fizzing overflow with which we are familiar.
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