Answer
Hypochlorous acid and hypochlorite ion are capable of making a buffer solution with this hydronium ion concentration.
Work Step by Step
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.
