Re: When a human exhales CO2 is carbonic acid created when it mixes with H2O?

Randy,
    You are correct.  The carbon dioxide from your breath reacts with water 
to form carbonic acid, H2CO3.  This is an equilibrium process, where 
carbonic acid decomposes into water and carbon dioxide, in competition with 
the reverse reaction.  The more carbon dioxide that is present in the water, 
the more carbonic acid will be present.  This is the same acid that is 
present in carbonated beverages.