Solved: A glass of water initially at pH 7.0 is exposed to

Chapter 20, Problem 72P

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A glass of water initially at pH 7.0 is exposed to dry air at sea level at \(20^{\circ} \mathrm{C}\). Calculate the pH of the water when equilibrium is reached between atmospheric \(\mathrm{CO}_{2}\) and \(\mathrm{CO}_{2}\) dissolved in the water, given that Henry's law constant for \(\mathrm{CO}_{2}\) at \(20^{\circ} \mathrm{C}\) is \(0.032\mathrm{\ mol}/\mathrm{L}\cdot\mathrm{atm}\). (Hint: Assume no loss of water due to evaporation and use Table 20.1 to calculate the partial pressure of \(\mathrm{CO}_{2}\). Your answer should correspond roughly to the pH of rainwater.)