What is the role of CO2 in soda water or in any other beverages? While drinking soda water, is there any use of this CO2 to our body?We used to...

When CO2 is dissolved in water it combines with a water
molecule to form carbonic acid - H2CO3.  As long as this drink is under pressure, the
CO2 stays dissolved.  When the pressure is released, some of the CO2 escapes as fizz, or
bubbles.  The carbonated water changes the taste of the water, and also gives it that
acidic "bite' that you sense when you drink it.  Any CO2 that you ingest is either
released through burping or some may enter the blood stream where it would be buffered
by the other components in the blood.