Due to increased CO2 in the atmosphere, the pH of rainwater is more acidic than in the previous

century. Use the following data to calculate the pH of unpolluted rainwater at 25°C: vol% in air of CO2
= 0.033; solubility of CO2 in pure water at 25°C and 1 atm = 88 mL CO2 per 100 mL H2O; Ka1 of H2CO3 =
4.5 × 10–7.