Why does pop only get fizzy when opened?

Question

When I look at an unopened pop in a bottle it's flat but when I open it it gets so fizzy? why is this?

Answer 1

all pop is, is carbonated water, surgar, and flavoring. the carbon gases build up when seal in the bottle.all that gas reacts (released)     when opened

Answer 2

Is the reaction of the carbon dioxide with the air.

Answer 3

diffusion - when the bottle is opened the carbon dioxide has somewhere to move to

Answer 4

its not a reaction with the air.  its a pressure differential.

the soda bottle/can is presurized, which keeps the CO2 in the liquid.  when the bottle is opened, the pressure release allows the gas to escape from the liquid to the air (less pressure)  thus, fizzing up the liquid.