Answer
(a) $pH = 3.45$
(b) $pH = 11.98$
(c) $pH = 2.58$
(d) $pH = 10.81$
Work Step by Step
1. Calculate the pOH:
$pOH = -log[OH^-]$
$pOH = -log( 2.8 \times 10^{- 11})$
$pOH = 10.55$
2. Find the pH:
$pH + pOH = 14$
$pH + 10.55 = 14$
$pH = 3.45$
3. Calculate the pOH:
$pOH = -log[OH^-]$
$pOH = -log( 9.6 \times 10^{- 3})$
$pOH = 2.02$
4. Find the pH:
$pH + pOH = 14$
$pH + 2.02 = 14$
$pH = 11.98$
5. Calculate the pOH:
$pOH = -log[OH^-]$
$pOH = -log( 3.8 \times 10^{- 12})$
$pOH = 11.42$
6. Find the pH:
$pH + pOH = 14$
$pH + 11.42 = 14$
$pH = 2.58$
7. Calculate the pOH:
$pOH = -log[OH^-]$
$pOH = -log( 6.4 \times 10^{- 4})$
$pOH = 3.19$
8. Find the pH:
$pH + pOH = 14$
$pH + 3.19 = 14$
$pH = 10.81$