## Chemistry: The Molecular Science (5th Edition)

1. Calculate the pH value for this hydronium ion concentration: $pH = -log[H_3O^+]$ $pH = -log( 7.0 \times 10^{- 8})$ $pH = 7.15$ 2. Using the Table 15.1, identify the conjugate pair with $pKa$ closest to $7.15$ - Hypochlorous acid and hypochlorite ion: $7.17$ ** Dihydrogen phosphate ion and Carbonic acid pairs can be used too, but, the hypochlorous is more adequate. ** Remember, this difference must be lower than 1, because this is approximately the pH range of a buffer solution.