Sound absorption in sea water involves chemical equilibria with rather slow relaxation rates. The low‐frequency range of the resonator method is limited by practical considerations of size and experimental conditions must usually be altered to place the relaxation frequency within the measurement window. For relaxations involving acids or bases, the temperature‐jumppH method permits rate measurements below a limit set by indicator response (∼ 105/s). RecentT‐jump studies confirm unambiguously that the low‐frequency (∼ 1 kHz) relaxation mechanism in sea water is an acid‐base exchange between boric acid and carbonate [P. Malloet al., J. Phys. Chem. (in press) (1984)]. Further investigations of the boric acid exchange in similar Lewis systems, e.g., ammonia, reveal single relaxations with comparable rates. The magnesium carbonate ion‐pair equilibrium—a minor component of sea water absorption at mid‐frequencies (∼ 10 kHz)—shows more complex behavior with several identifiable relaxations in the measurement range. The magnesium sulfate relaxation (∼ 100 kHz) is unsuited to the method because of both speed and lack ofpH dependence. Visiting scientist; home address: 117 Boston Post Road, Old Lyme, CT 06320.