Rhythmdvl –
I still stick by my HCl burning the nose idea. I did some experimenting today. If I drink a soft drink, and the liquid degasses in my throat (immediately after taking a swig, and before it gets to my stomach)… no matter how large the burp was, there was no burn in my nose. If the burp came up from my stomach (in other words, after a period of not drinking anything), I got a burning sensation in my nose. Both types of burp would consist of mostly CO2, so if it were the CO2 that was burning wouldn’t both burps feel the same to my nose?
As to why all burps (that come from the stomach, and not the throat) don’t burn… I would think that soda burps would tend to be MUCH more voluminous (you are putting quite a bit of gas into your stomach with each sip), thus being more apt to carry nose sensitive amounts of HCl.
labdude –
Yes, you are right. I just looked up the MSDS for CO2, and it was labeled as “Toxic”. The average lethal (due to acute toxicity) concentration was listed as 9% over a period of five minutes (the normal atmospheric concentration of CO2 is 0.035%). IIRC, the CO2 scrubbers also serve to concentrate the CO2 for use in recycling the oxygen, so that there does not have to be a huge new supply of oxygen constantly being added to the breathable atmosphere.
Wood Thrush –
I would imagine that they are so popular because they are convenient, and they taste good. I think that the pain is an issue to a small percentage of the general population. The perceived benefit (convenience and good flavor) is greater than the perceived sacrifice (mild pain and calories). Also, there is the attraction of getting to be like <insert celebrity’s name here>.