Carbon dioxide dissolves in water to form carbonic acid, which is primarily dissolved CO2. Dissolved CO2 satisfies the equilibrium equation:

CO2 (g) <----> CO2 (aq) K=0.032

The acid dissociation constants listed in most standard reference texts for carbonic acid actually apply to dissolved CO2.
For a CO2 partial pressure of 4.4×10-4 atm in the atmosphere, what is the pH of water in equilibrium with the atmosphere?