The pH of ocean water depends on the amount of atmospheric carbon dioxide. The dissolution of carbon dioxide in ocean water can be approximated by the following chemical reactions (Henry’s Law constant for CO₂ is K_H = [CO₂(aq)]/[CO₂(g)] = 0.8317.) For reaction (2), K = 2.8 x 10^-9:

(a) Use the equations above to determine the hydronium ion concentration as a function of [CO2(g)] and [Ca²⁺].

(b) During preindustrial conditions, we will assume that the equilibrium concentration of [CO₂(g)] = 280 ppm and [Ca²⁺] = 10.24 mM. Calculate the pH of a sample of ocean water.

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CO2(g) — CO2(aq) (1) CaCO3(s) Ca²+ (aq) + CO3(aq) (2) H3O+ (aq) + CO3(aq) — HCO3(aq) + H₂O(1) (3) H3O+ (aq) + HCO3(aq) CO₂(aq) + 2 H₂O(1) (4) =