## Chemistry (7th Edition)

$C_6H_5CO_2H$ and $C_6H_5C{O_2}^-$ are the best pair, because the $pK_a$ for benzoic acid is the closest to 4.50.
1. Calculate the pKa value for $HS{O_4}^-$ $pKa = -log(Ka)$ $pKa = -log( 0.012)$ $pKa = 1.92$ 2. Calculate the pKa value for $HOCl$ $pKa = -log(Ka)$ $pKa = -log( 3.5 \times 10^{- 8})$ $pKa = 7.46$ 3. Calculate the pKa value for $C_6H_5CO_2H$ $pKa = -log(Ka)$ $pKa = -log( 6.5 \times 10^{- 5})$ $pKa = 4.19$