Why do fizzy (or soft) drinks go flat, when you leave the cap off, on warm days?

Question

Hey! Just wondering if anyone knew the answer to this question. It was puzzling me.. Thanks! =]

Answer 1

The CO2 gas was forced into the soda under pressure, so taking off the cap reduces the pressure and some comes out. Also, less gas can be dissolved in warmer liquid than cold, so as the soda gets warm, more and more of the gas escapes.

Answer 2

http://en.wikipedia.org/wiki/Carbonation

good question

Answer 3

The thing that makes soda fizzy is carbon dioxide gas dissolved in the soda.  The gas stays in equilibrium in the liquid because of pressure.  When you remove the pressure, it releases CO2 (that's the hiss when you first open the bottle), and the longer it stays unpressurized, the more carbonation it loses.  The cap is what keeps the soda pressurized.

Answer 4

t has to do with vapor pressure.  CO2 is the gas forced into the soft drink which makes it fizzy.  When the cap is left off, the vapor pressure in the head space of the bottle drops, allowing the remaining CO2 to escape from the liquid.