Solution: When carbon dioxide dissolves in water, it undergoes a multistep equilibrium process, with Koverall = 4.5 x 10−7, which is simplified to the following: CO2(g) + H2O(l) ⇌ H2CO3(aq) H2CO3(aq) + H2O(l) ⇌

When carbon dioxide dissolves in water, it undergoes a multistep equilibrium process, with Koverall = 4.5 x 10⁻⁷, which is simplified to the following: 

CO₂(g) + H₂O(l) ⇌ H₂CO₃(aq) 

H₂CO₃(aq) + H₂O(l) ⇌ HCO₃⁻(aq) + H₃O⁺(aq)

(b) What is the pH of nonpolluted rainwater in equilibrium with clean air (PCO ₂ in clean air = 4 x 10⁻⁴ atm; Henry’s law constant for CO ₂ at 25°C is 0.033 mol/L•atm)?