Calculate [CO32-] in a 0.026 M solution of CO2 in water (H2CO3).?

Question

Calculate [CO32-] in a 0.026 M solution of CO2 in water (H2CO3). If all the CO32- in this solution comes from the reaction shown below, what percentage of the H+ ions in the solution is a result of the dissociation of HCO3-?

HCO3-(aq)<---->H+(aq) + CO32-(aq)

Answer 1

Carbon dioxide dissolved in water is in equilibrium with carbonic acid:
CO2 + H2O <==> H2CO3
The equilibrium constant at 25°C is Kh= 1.70×10^−3. Hence, the majority of the carbon dioxide is not converted into carbonic acid and stays as CO2 molecules.

I am confused with your statement "Calculate [CO32-] in a 0.026 M solution of CO2 in water (H2CO3). " Do you mean [CO2] = 0.026M or [H2CO3] = 0.026M? Please specify.
This is an envolved problem, since there are three equilibrium equations:
CO2 + H2O <==> H2CO3, Kh= 1.70×10^−3.
H2CO3 <==> H+ + HCO3-, Ka1 = 2.5×10^−4 mol/L
HCO3- <==> H+ + CO3(2-), Ka2 = 5.61×10^−11 mol/L