Why does regular Coke fizz when you shake the bottle?
When you crack the lid after shaking the now higher pressure of the dissolved CO2 gas the now 6 psi is free to expand and does so immediately and the coke liquid is carried out with the gas expanding to atmosphere. If you leave the lid on eventually the 6 psi dissolved gas would equalize again with the lower 5psi headspace and the pop wouldn’t fizz beyond the normal whish sound.
