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 6.1×10-4 atm in the atmosphere, what is the pH of water in equilibrium with the atmosphere?

i've literally tried this 9 times and got it wrong everytime, please help!